Blew another damn transformer on my Trane XB80
A continuation of the "Why does the 115V-24V transformer keep blowing on my
Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. I never got a real chance to test out the system after installing this third transformer. We had cool weather for several days, and I never tried to force the system to come on so I could monitor it; that was probably a mistake. Unfortunately, I was also absent from the premises during the extended times when the unit was most likely operational, so that didn't help either. However, my family tells me that it WAS working and cooling the house rather nicely, for at least a day, perhaps two. I'm getting 115V in all the right places, so it doesn't look like an over-voltage condition to me. Perhaps it's an overheating condition? It looks to me like the only real load on this circuit is the blower motor; could the motor be causing this? The blower spins freely when I turn it by hand. Start capacitor on the motor maybe? Relay on the control board perhaps? |
Blew another damn transformer on my Trane XB80
On 4/8/2011 5:52 PM Steve Turner spake thus:
A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. -- The current state of literacy in our advanced civilization: yo wassup nuttin wan2 hang k where here k l8tr by - from Usenet (what's *that*?) |
Blew another damn transformer on my Trane XB80
Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. I never got a real chance to test out the system after installing this third transformer. We had cool weather for several days, and I never tried to force the system to come on so I could monitor it; that was probably a mistake. Unfortunately, I was also absent from the premises during the extended times when the unit was most likely operational, so that didn't help either. However, my family tells me that it WAS working and cooling the house rather nicely, for at least a day, perhaps two. I'm getting 115V in all the right places, so it doesn't look like an over-voltage condition to me. Perhaps it's an overheating condition? It looks to me like the only real load on this circuit is the blower motor; could the motor be causing this? The blower spins freely when I turn it by hand. Start capacitor on the motor maybe? Relay on the control board perhaps? Hi, Is the x-former gets hot when in use? Unless it is under rated for the application, it should npot blow so often. It is just 120-24V AC step down tranny. Buy one of hevier one(bigger size and really heavier in weight than stock) If it blows again, something on the load side is wrong. |
Blew another damn transformer on my Trane XB80
On 4/8/2011 8:44 PM, Tony Hwang wrote:
Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. .... ... Buy one of hevier one(bigger size and really heavier in weight than stock) If it blows again, something on the load side is wrong. I'd venture something is already wrong... -- |
Blew another damn transformer on my Trane XB80
On Apr 8, 9:05*pm, dpb wrote:
On 4/8/2011 8:44 PM, Tony Hwang wrote: Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. ... ... Buy one of hevier one(bigger size and really heavier in weight than stock) If it blows again, something on the load side is wrong. I'd venture something is already wrong... -- Put a voltmeter on the secondary side and measure the voltage when it is not running. THen turn on the AC and see what the secondary voltage does. IF it is supposed to operate a relay, and the current draw is appropriate for the size transformer you have, I would not expect the voltage to drop by more than 20%. Then leaving the AC on, for at least 1/2 hour, keep monitoring the transformer tempoerature. If it is a gradual heating, see how hot it gets. If there is a severe overload, the transform may blow out before it even gets hot to the touch. If it just gets warm over 10 - 20 minutes, then that is probably about normal. IF you can find out what the correct current drain is supposed to be, I would go for a transformer with double that amperage ratinbg just ot be ultra-safe. But you have to be there and monitor things, coming back 48 hours later is not going to work!!! |
Blew another damn transformer on my Trane XB80
On 4/8/2011 8:52 PM, Steve Turner wrote:
A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). Three times it fried the primary? I'd guess it's getting 240vac at times. It's very unusual for the primary to go bad from a short on the secondary side, and the picture shows that the secondary wasn't overheated like the primary was. Where's all those electricians talking about an open neutrals when you need them? If it measures 120vac tie a light bulb into the primary side and leave it where it can be seen. Have the family let you know if it ever gets brighter than normal. Or better yet, call a pro. |
Blew another damn transformer on my Trane XB80
On 4/8/2011 7:58 PM, David Nebenzahl wrote:
On 4/8/2011 5:52 PM Steve Turner spake thus: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. Thinking maybe I should spring for a transformer with a manual reset, like this one: http://www.pexsupply.com/White-Rodge...unt-14937000-p Would that protect me from having to replace the damn transformer every time? It looks like the circuit breaker is on the 24V output side; I'm a little fuzzy on how that would protect the input side of the transformer...? |
Blew another damn transformer on my Trane XB80
On 4/8/2011 10:16 PM, Tony Miklos wrote:
On 4/8/2011 8:52 PM, Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). Three times it fried the primary? I'd guess it's getting 240vac at times. It's very unusual for the primary to go bad from a short on the secondary side, and the picture shows that the secondary wasn't overheated like the primary was. Where's all those electricians talking about an open neutrals when you need them? If it measures 120vac tie a light bulb into the primary side and leave it where it can be seen. Have the family let you know if it ever gets brighter than normal. Or better yet, call a pro. That very thought crossed my mind, but I'm not sure how that could happen. The unit is on a dedicated 115V circuit tied to a single-pole breaker. Where would the possibility exist for the neutral to become hot? In the breaker box? |
Blew another damn transformer on my Trane XB80
On 4/8/2011 8:22 PM Steve Turner spake thus:
On 4/8/2011 7:58 PM, David Nebenzahl wrote: On 4/8/2011 5:52 PM Steve Turner spake thus: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. Thinking maybe I should spring for a transformer with a manual reset, like this one: http://www.pexsupply.com/White-Rodge...unt-14937000-p Would that protect me from having to replace the damn transformer every time? It looks like the circuit breaker is on the 24V output side; I'm a little fuzzy on how that would protect the input side of the transformer...? Why in the world would you think you need to protect the primary side? Unless you've got a *really* weird problem--namely, severe overvoltage spikes--there's no way the damage is coming from that side. It's got to be because of overcurrent on the secondary side. Unless there's something really messed up with your house's wiring ... -- The current state of literacy in our advanced civilization: yo wassup nuttin wan2 hang k where here k l8tr by - from Usenet (what's *that*?) |
Blew another damn transformer on my Trane XB80
On 4/8/2011 11:38 PM, David Nebenzahl wrote:
On 4/8/2011 8:22 PM Steve Turner spake thus: On 4/8/2011 7:58 PM, David Nebenzahl wrote: On 4/8/2011 5:52 PM Steve Turner spake thus: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. Thinking maybe I should spring for a transformer with a manual reset, like this one: http://www.pexsupply.com/White-Rodge...unt-14937000-p Would that protect me from having to replace the damn transformer every time? It looks like the circuit breaker is on the 24V output side; I'm a little fuzzy on how that would protect the input side of the transformer...? Why in the world would you think you need to protect the primary side? Well I'm no electrician so I don't *know*. What I really mean is that I want to protect *myself* from having to drop $20 or $30 a pop on a half-dozen transformers while I'm trying to figure out what's wrong. So again, would the transformer referenced above protect me from that? Many helpful things are being suggested, but unfortunately they all seem to require testing the unit while it's operational, and I can't do that unless I have a working transformer installed. Unless you've got a *really* weird problem--namely, severe overvoltage spikes--there's no way the damage is coming from that side. It's got to be because of overcurrent on the secondary side. Ok, and how does that condition come into existence? Is there anything in the wiring diagram that jumps out at you as a potential candidate? I have two identical Trane AC/furnace units; one upstairs and one down. Should I swap control boards between units to see if the problem follows the control board? Unless there's something really messed up with your house's wiring ... The house is only six years old. Nothing's changed in terms of wiring and everything's been fine up until now. |
Blew another damn transformer on my Trane XB80
In article ,
Steve Turner wrote: snip You might start at the beginning and make sure everything is hooked up correctly. I mean, once you spring for yet another transformer. For example, your latest fried transformer has six wires. The schematic shows the secondary wire colors as blue and red. Given the location of the blue and red wires on the pic of the transformer you have, that's not quite intuitive. And, it may not even be right. So I'd buy a new one, and check some voltages on the bench. Put 120 into the black and white, and then measure every other pair to make sure you understand which two wires are really putting out 24 V. Obviously, when you go to install it, clip and shrink tube the unused wires, and make sure that leads are dressed so that they won't short anywhere. Then I'd be monitoring the damn thing, preferably with a voltmeter perhaps on the primary and an ammeter on the secondary. |
Blew another damn transformer on my Trane XB80
In article
, Smitty Two wrote: In article , Steve Turner wrote: snip You might start at the beginning and make sure everything is hooked up correctly. I mean, once you spring for yet another transformer. For example, your latest fried transformer has six wires. The schematic shows the secondary wire colors as blue and red. Given the location of the blue and red wires on the pic of the transformer you have, that's not quite intuitive. And, it may not even be right. So I'd buy a new one, and check some voltages on the bench. Put 120 into the black and white, and then measure every other pair to make sure you understand which two wires are really putting out 24 V. Obviously, when you go to install it, clip and shrink tube the unused wires, and make sure that leads are dressed so that they won't short anywhere. Then I'd be monitoring the damn thing, preferably with a voltmeter perhaps on the primary and an ammeter on the secondary. And I'll add that I'd treat this as a single failure. The first transformer lasted 6 years and probably only has an open $2 thermal fuse. The second transformer was a cheap knockoff. So don't worry about those. Focus on this one. The arcing looks like a hard short. And note the note on the wiring diagram about minding the hot lead going to the correct place. Verify the hot lead independently of the damn wire color. |
Blew another damn transformer on my Trane XB80
On 4/9/2011 12:38 AM, David Nebenzahl wrote:
On 4/8/2011 8:22 PM Steve Turner spake thus: On 4/8/2011 7:58 PM, David Nebenzahl wrote: On 4/8/2011 5:52 PM Steve Turner spake thus: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. Thinking maybe I should spring for a transformer with a manual reset, like this one: http://www.pexsupply.com/White-Rodge...unt-14937000-p Would that protect me from having to replace the damn transformer every time? It looks like the circuit breaker is on the 24V output side; I'm a little fuzzy on how that would protect the input side of the transformer...? Why in the world would you think you need to protect the primary side? Look at the picture. The primary side has been overheated, the secondary side looks fine. Looks like an over voltage problem to me. |
Blew another damn transformer on my Trane XB80
On 4/9/2011 12:19 AM, Steve Turner wrote:
On 4/8/2011 10:16 PM, Tony Miklos wrote: On 4/8/2011 8:52 PM, Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). Three times it fried the primary? I'd guess it's getting 240vac at times. It's very unusual for the primary to go bad from a short on the secondary side, and the picture shows that the secondary wasn't overheated like the primary was. Where's all those electricians talking about an open neutrals when you need them? If it measures 120vac tie a light bulb into the primary side and leave it where it can be seen. Have the family let you know if it ever gets brighter than normal. Or better yet, call a pro. That very thought crossed my mind, but I'm not sure how that could happen. The unit is on a dedicated 115V circuit tied to a single-pole breaker. Where would the possibility exist for the neutral to become hot? In the breaker box? It happens all the time. |
Blew another damn transformer on my Trane XB80
"Steve Turner" wrote in message
... On 4/8/2011 10:16 PM, Tony Miklos wrote: On 4/8/2011 8:52 PM, Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). Three times it fried the primary? I'd guess it's getting 240vac at times. It's very unusual for the primary to go bad from a short on the secondary side, and the picture shows that the secondary wasn't overheated like the primary was. Where's all those electricians talking about an open neutrals when you need them? If it measures 120vac tie a light bulb into the primary side and leave it where it can be seen. Have the family let you know if it ever gets brighter than normal. Or better yet, call a pro. That very thought crossed my mind, but I'm not sure how that could happen. The unit is on a dedicated 115V circuit tied to a single-pole breaker. Where would the possibility exist for the neutral to become hot? In the breaker box? A neutral in a breaker box could have a loose connection. These connections can heat up and cool down as more/less electricity is used on the panel in question. And there may be a point where the connection fails momentarily or arcs. Then if you lose the neutral connection, 120 volt circuits become 240 volt circuits via other circuits turned on in the panel on the other leg. The solution to that problem is usually to have the electric company or electrician retorque the main panel lug nuts to the panel manufacturers tightness specifications in inch lbs. Note POWER IS ALWAYS HOT TO THESE CONNECTIONS and this is NOT a DIY thing! A similar problem can be with what is called a MWBC or Multi-Wire Branch Circuit. These are 2 separate 120 V circuits run to the same area that share one neutral wire. So 2 hots and 1 neutral coming from the breaker panel. A loose neutral connection with that one wire and same problem. When the entire panel is having this problem, you would see lights get brighter as the problem occurs. If just a problem with one MWBC, then only those circuits would have the problem. |
Blew another damn transformer on my Trane XB80
On Apr 8, 10:05*pm, dpb wrote:
On 4/8/2011 8:44 PM, Tony Hwang wrote: Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. ... ... Buy one of hevier one(bigger size and really heavier in weight than stock) If it blows again, something on the load side is wrong. I'd venture something is already wrong... -- I'd agree. Responding to his first post and before he put this latest transformer in I recommended measuring how many amps are being drawn on the low voltage side. This is electricity 101. So, he comes here asking for advice and instead of listening, he justs puts another transformer in and blows it too..... Go figure. Time to either get educated or hire a pro. |
Blew another damn transformer on my Trane XB80
On Apr 9, 9:53*am, "Bill" wrote:
"Steve Turner" wrote in message ... On 4/8/2011 10:16 PM, Tony Miklos wrote: On 4/8/2011 8:52 PM, Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...product/22-166.... As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). Three times it fried the primary? I'd guess it's getting 240vac at times. It's very unusual for the primary to go bad from a short on the secondary side, and the picture shows that the secondary wasn't overheated like the primary was. Where's all those electricians talking about an open neutrals when you need them? If it measures 120vac tie a light bulb into the primary side and leave it where it can be seen. Have the family let you know if it ever gets brighter than normal. Or better yet, call a pro. That very thought crossed my mind, but I'm not sure how that could happen. *The unit is on a dedicated 115V circuit tied to a single-pole breaker. *Where would the possibility exist for the neutral to become hot? *In the breaker box? A neutral in a breaker box could have a loose connection. These connections can heat up and cool down as more/less electricity is used on the panel in question. And there may be a point where the connection fails momentarily or arcs. Then if you lose the neutral connection, 120 volt circuits become 240 volt circuits via other circuits turned on in the panel on the other leg. The solution to that problem is usually to have the electric company or electrician retorque the main panel lug nuts to the panel manufacturers tightness specifications in inch lbs. Note POWER IS ALWAYS HOT TO THESE CONNECTIONS and this is NOT a DIY thing! A similar problem can be with what is called a MWBC or Multi-Wire Branch Circuit. These are 2 separate 120 V circuits run to the same area that share one neutral wire. So 2 hots and 1 neutral coming from the breaker panel. A loose neutral connection with that one wire and same problem. When the entire panel is having this problem, you would see lights get brighter as the problem occurs. If just a problem with one MWBC, then only those circuits would have the problem.- Hide quoted text - - Show quoted text - The problem with that theory is that the 120V circuit that supplies power to the transformer also powers the rest of the furnace, ie the inducer blower, main blower, etc. If it were getting 240V, one would think by now one of those other components would have failed. Also, with 240V it would be delivering 48V to the logic board, which one would think would have opened a fuse on it or destroyed some electronics by now. I can't say I can make much sense of what is going on either. But until someone with some basic electric skills capable of taking some measurements looks at it, I doubt we're gonna fix it by remote analysis. |
Blew another damn transformer on my Trane XB80
On Apr 9, 10:21*am, "
wrote: On Apr 9, 9:53*am, "Bill" wrote: "Steve Turner" wrote in message ... On 4/8/2011 10:16 PM, Tony Miklos wrote: On 4/8/2011 8:52 PM, Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...product/22-166... As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). Three times it fried the primary? I'd guess it's getting 240vac at times. It's very unusual for the primary to go bad from a short on the secondary side, and the picture shows that the secondary wasn't overheated like the primary was. Where's all those electricians talking about an open neutrals when you need them? If it measures 120vac tie a light bulb into the primary side and leave it where it can be seen. Have the family let you know if it ever gets brighter than normal. Or better yet, call a pro. That very thought crossed my mind, but I'm not sure how that could happen. *The unit is on a dedicated 115V circuit tied to a single-pole breaker. *Where would the possibility exist for the neutral to become hot? *In the breaker box? A neutral in a breaker box could have a loose connection. These connections can heat up and cool down as more/less electricity is used on the panel in question. And there may be a point where the connection fails momentarily or arcs. Then if you lose the neutral connection, 120 volt circuits become 240 volt circuits via other circuits turned on in the panel on the other leg. The solution to that problem is usually to have the electric company or electrician retorque the main panel lug nuts to the panel manufacturers tightness specifications in inch lbs. Note POWER IS ALWAYS HOT TO THESE CONNECTIONS and this is NOT a DIY thing! A similar problem can be with what is called a MWBC or Multi-Wire Branch Circuit. These are 2 separate 120 V circuits run to the same area that share one neutral wire. So 2 hots and 1 neutral coming from the breaker panel. A loose neutral connection with that one wire and same problem. When the entire panel is having this problem, you would see lights get brighter as the problem occurs. If just a problem with one MWBC, then only those circuits would have the problem.- Hide quoted text - - Show quoted text - The problem with that theory is that the 120V circuit that supplies power to the transformer also powers the rest of the furnace, ie the inducer blower, main blower, etc. *If it were getting 240V, one would think by now one of those other components would have failed. *Also, with 240V it would be delivering 48V to the logic board, which one would think would have opened a fuse on it or destroyed some electronics by now. I can't say I can make much sense of what is going on either. *But until someone with some basic electric skills capable of taking some measurements looks at it, I doubt we're gonna fix it by remote analysis. To OP, I'm not going to wade through all the previous posts... you pictures show a transformer with 6 leads. the wiring diagrams show a transformer with 4 leads how are you connecting the transformer.. Do you have a voltmeter... when you connected the transformer does it blow up immediately or after a time? Did you check the pri and sec voltages.. A failure like shown in the pic with big black scorch marks would indicate a MAJOR overload like you have connected the transformer completely wrong ...or there is some metal box or something that shorts to the terminals. Does the main breaker blow too? Find a ham radio guy or someone that knows a bit about electricity to help you. Mark |
Blew another damn transformer on my Trane XB80
On 4/9/2011 8:30 AM, Tony Miklos wrote:
On 4/9/2011 12:38 AM, David Nebenzahl wrote: On 4/8/2011 8:22 PM Steve Turner spake thus: On 4/8/2011 7:58 PM, David Nebenzahl wrote: On 4/8/2011 5:52 PM Steve Turner spake thus: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. Thinking maybe I should spring for a transformer with a manual reset, like this one: http://www.pexsupply.com/White-Rodge...unt-14937000-p Would that protect me from having to replace the damn transformer every time? It looks like the circuit breaker is on the 24V output side; I'm a little fuzzy on how that would protect the input side of the transformer...? Why in the world would you think you need to protect the primary side? Look at the picture. The primary side has been overheated, the secondary side looks fine. Looks like an over voltage problem to me. I wonder if our intrepid OP has done the basics involved in troubleshooting instead of flitting around from place to place? In the case of a power problem, you always start at the source by measuring voltage and current. It could be a very simple problem like a bit of insulation skinned off a thermostat wire that only shorts out when everything is buttoned up and vibration from the running unit causes the short circuit. If you ever watched the TV program MASH, you would see the surgeons run the intestines looking for a nick in the wall of the organ. Wiring is the same way sometimes. I'll inspect the wiring and often find a small cut or tiny area where insulation is missing and sometimes the wire is bent over a sharp edge of the cabinet where it's fine until you close things up. I wonder if the supply voltage to the transformer is what it's supposed to be? Most domestic household air handler/furnaces are powered by 120vac but some may require 240vac if there are electric heat strips. I would check the voltage feeding the transformer first. TDD |
Blew another damn transformer on my Trane XB80
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Blew another damn transformer on my Trane XB80
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Blew another damn transformer on my Trane XB80
On 4/9/2011 10:29 AM, The Daring Dufas wrote:
On 4/9/2011 8:30 AM, Tony Miklos wrote: On 4/9/2011 12:38 AM, David Nebenzahl wrote: On 4/8/2011 8:22 PM Steve Turner spake thus: On 4/8/2011 7:58 PM, David Nebenzahl wrote: On 4/8/2011 5:52 PM Steve Turner spake thus: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. Thinking maybe I should spring for a transformer with a manual reset, like this one: http://www.pexsupply.com/White-Rodge...unt-14937000-p Would that protect me from having to replace the damn transformer every time? It looks like the circuit breaker is on the 24V output side; I'm a little fuzzy on how that would protect the input side of the transformer...? Why in the world would you think you need to protect the primary side? Look at the picture. The primary side has been overheated, the secondary side looks fine. Looks like an over voltage problem to me. I wonder if our intrepid OP has done the basics involved in troubleshooting instead of flitting around from place to place? In the case of a power problem, you always start at the source by measuring voltage and current. It could be a very simple problem like a bit of insulation skinned off a thermostat wire that only shorts out when everything is buttoned up and vibration from the running unit causes the short circuit. If you ever watched the TV program MASH, you would see the surgeons run the intestines looking for a nick in the wall of the organ. Wiring is the same way sometimes. I'll inspect the wiring and often find a small cut or tiny area where insulation is missing and sometimes the wire is bent over a sharp edge of the cabinet where it's fine until you close things up. I wonder if the supply voltage to the transformer is what it's supposed to be? Most domestic household air handler/furnaces are powered by 120vac but some may require 240vac if there are electric heat strips. I would check the voltage feeding the transformer first. TDD Yes, I've done all those things. The supply voltage is fine. I've inspected the wiring at great length and can find no evidence of problems; it all looks pristine. It's a gas furnace, and there are no 220 circuits running anywhere near that area of the house. Thanks. |
Blew another damn transformer on my Trane XB80
On 4/9/2011 10:59 AM, The Daring Dufas wrote:
On 4/9/2011 10:48 AM, Steve Turner wrote: On 4/9/2011 9:12 AM, wrote: On Apr 8, 10:05 pm, wrote: On 4/8/2011 8:44 PM, Tony Hwang wrote: Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. ... ... Buy one of hevier one(bigger size and really heavier in weight than stock) If it blows again, something on the load side is wrong. I'd venture something is already wrong... -- I'd agree. Responding to his first post and before he put this latest transformer in I recommended measuring how many amps are being drawn on the low voltage side. This is electricity 101. So, he comes here asking for advice and instead of listening, he justs puts another transformer in and blows it too..... Go figure. Time to either get educated or hire a pro. In case you hadn't noticed, I've been getting LOTS of (much appreciated) advice from many people, but it's also been very contradictory with no single suggested approach. It's been an interesting and informative discussion, and I've been happy that nobody's been a jerk about it... until *now*. And I DID listen; plenty of people suggested that the original transformer was likely to be under-rated and to replace it with something more heavy-duty. Also, it seems to me that having a working transformer is a pre-requisite to following your advice of measuring the amp draw on the low voltage side, no? Unfortunately, time constraints prevented me from being there to perform those measurements when the unit was running, and unfortunately again the transformer blew in my absence. But of course, I'm repeating myself... Steve I really hope you can figure out the problem with the furnace and I can understand the bit about time constraints. Installing a fuse in series with with either side of the transformer is cheap insurance to keep from losing another transformer. The fuse holders are inexpensive and it's a lot less of a hassle to replace a blown fuse. TDD Yes, I would be more than willing to do that, but my electricity training is not quite up to the 101 level that trader4 seems to think I should have; can you suggest a specific fuse rating that I should use? Thanks! |
Blew another damn transformer on my Trane XB80
On Apr 9, 11:48*am, Steve Turner
wrote: On 4/9/2011 9:12 AM, wrote: On Apr 8, 10:05 pm, *wrote: On 4/8/2011 8:44 PM, Tony Hwang wrote: Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. ... ... Buy one of hevier one(bigger size and really heavier in weight than stock) If it blows again, something on the load side is wrong. I'd venture something is already wrong... -- I'd agree. *Responding to his first post and before he put this * latest transformer in I recommended measuring how many amps are being drawn on the low voltage side. * * This is electricity 101. * So, he comes here asking for advice * and instead of listening, he justs puts another transformer in * and blows it too..... * Go figure. * Time to either get educated or hire a pro. In case you hadn't noticed, I've been getting LOTS of (much appreciated) advice from many people, but it's also been very contradictory with no single suggested approach. *It's been an interesting and informative discussion, and I've been happy that nobody's been a jerk about it... until *now*. OK, so now I'm a jerk for suggesting that you should have taken some basic measurements, starting with the transformer output current, instead of just continuing to replace transformers and watch them blow. A component that supplies power fails by burning up. You've replaced it several times now. You think just MAYBE it's a good idea to see how much power it's be asked to supply instead of just buyng new transformers? If a fuse blew out, would you just keep putting in new fuses or would you measure the current and see what it is? I'd have measured the voltages and currents on both sides of the transformer after the first one failed. *And I DID listen; plenty of people suggested that the original transformer was likely to be under-rated and to replace it with something more heavy-duty. I find it hard to believe that Trane uses transformers in it's furnaces that are so under-rated that they burn out in a day. I also question the soundness of anyone telling you to start installing transformers capable of delivering more power without even taking some basic measurements and finding out what's drawing current and if it's excessive for some reason. If you had a light circuit that was blowing fuses, would your approach be to put in a bigger fuse or would it be to find out what's really going on? If you have a short somewhere and you put in a large enough transformer, you think you might eventually heat something up enough to start a fire, like maybe in the thermostat wiring in your walls? *Also, it seems to me that having a working transformer is a pre-requisite to following your advice of measuring the amp draw on the low voltage side, no? Unfortunately, time constraints prevented me from being there to perform those measurements when the unit was running, and unfortunately again the transformer blew in my absence. So, you had the time to obtain a new transformer, put it in, but didn't have the 1 minute it would take to use a VOM to measure the current and voltage on the secondary? If it were me and I saw transformers burning up, I wouldn't leave it on until I had some confidence as to what was going on. *But of course, I'm repeating myself Yes, by putting in each new transformer and watching it fail. |
Blew another damn transformer on my Trane XB80
On 4/9/2011 12:23 PM, Steve Turner wrote:
On 4/9/2011 10:59 AM, The Daring Dufas wrote: On 4/9/2011 10:48 AM, Steve Turner wrote: On 4/9/2011 9:12 AM, wrote: On Apr 8, 10:05 pm, wrote: On 4/8/2011 8:44 PM, Tony Hwang wrote: Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. ... ... Buy one of hevier one(bigger size and really heavier in weight than stock) If it blows again, something on the load side is wrong. I'd venture something is already wrong... -- I'd agree. Responding to his first post and before he put this latest transformer in I recommended measuring how many amps are being drawn on the low voltage side. This is electricity 101. So, he comes here asking for advice and instead of listening, he justs puts another transformer in and blows it too..... Go figure. Time to either get educated or hire a pro. In case you hadn't noticed, I've been getting LOTS of (much appreciated) advice from many people, but it's also been very contradictory with no single suggested approach. It's been an interesting and informative discussion, and I've been happy that nobody's been a jerk about it... until *now*. And I DID listen; plenty of people suggested that the original transformer was likely to be under-rated and to replace it with something more heavy-duty. Also, it seems to me that having a working transformer is a pre-requisite to following your advice of measuring the amp draw on the low voltage side, no? Unfortunately, time constraints prevented me from being there to perform those measurements when the unit was running, and unfortunately again the transformer blew in my absence. But of course, I'm repeating myself... Steve I really hope you can figure out the problem with the furnace and I can understand the bit about time constraints. Installing a fuse in series with with either side of the transformer is cheap insurance to keep from losing another transformer. The fuse holders are inexpensive and it's a lot less of a hassle to replace a blown fuse. TDD Yes, I would be more than willing to do that, but my electricity training is not quite up to the 101 level that trader4 seems to think I should have; can you suggest a specific fuse rating that I should use? Thanks! What were the specs of the original transformer? |
Blew another damn transformer on my Trane XB80
On 4/9/2011 12:19 AM, Steve Turner wrote:
On 4/8/2011 10:16 PM, Tony Miklos wrote: On 4/8/2011 8:52 PM, Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). Three times it fried the primary? I'd guess it's getting 240vac at times. It's very unusual for the primary to go bad from a short on the secondary side, and the picture shows that the secondary wasn't overheated like the primary was. Where's all those electricians talking about an open neutrals when you need them? If it measures 120vac tie a light bulb into the primary side and leave it where it can be seen. Have the family let you know if it ever gets brighter than normal. Or better yet, call a pro. That very thought crossed my mind, but I'm not sure how that could happen. The unit is on a dedicated 115V circuit tied to a single-pole breaker. Where would the possibility exist for the neutral to become hot? In the breaker box? Yes, it's called an open neutral. Can be quite dangerous. |
Blew another damn transformer on my Trane XB80
On 4/9/2011 11:55 AM, Steve Turner wrote:
On 4/9/2011 10:29 AM, The Daring Dufas wrote: On 4/9/2011 8:30 AM, Tony Miklos wrote: On 4/9/2011 12:38 AM, David Nebenzahl wrote: On 4/8/2011 8:22 PM Steve Turner spake thus: On 4/8/2011 7:58 PM, David Nebenzahl wrote: On 4/8/2011 5:52 PM Steve Turner spake thus: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. Thinking maybe I should spring for a transformer with a manual reset, like this one: http://www.pexsupply.com/White-Rodge...unt-14937000-p Would that protect me from having to replace the damn transformer every time? It looks like the circuit breaker is on the 24V output side; I'm a little fuzzy on how that would protect the input side of the transformer...? Why in the world would you think you need to protect the primary side? Look at the picture. The primary side has been overheated, the secondary side looks fine. Looks like an over voltage problem to me. I wonder if our intrepid OP has done the basics involved in troubleshooting instead of flitting around from place to place? In the case of a power problem, you always start at the source by measuring voltage and current. It could be a very simple problem like a bit of insulation skinned off a thermostat wire that only shorts out when everything is buttoned up and vibration from the running unit causes the short circuit. If you ever watched the TV program MASH, you would see the surgeons run the intestines looking for a nick in the wall of the organ. Wiring is the same way sometimes. I'll inspect the wiring and often find a small cut or tiny area where insulation is missing and sometimes the wire is bent over a sharp edge of the cabinet where it's fine until you close things up. I wonder if the supply voltage to the transformer is what it's supposed to be? Most domestic household air handler/furnaces are powered by 120vac but some may require 240vac if there are electric heat strips. I would check the voltage feeding the transformer first. TDD Yes, I've done all those things. The supply voltage is fine. I've inspected the wiring at great length and can find no evidence of problems; it all looks pristine. It's a gas furnace, and there are no 220 circuits running anywhere near that area of the house. Thanks. It doesn't take any 220 (240) circuits to cause that. |
Blew another damn transformer on my Trane XB80
What's the process, there? Neutral opens up, between the box
and the pole, and the power feeds in from the other leg? -- Christopher A. Young Learn more about Jesus www.lds.org .. "Tony Miklos" wrote in message ... On 4/9/2011 12:19 AM, Steve Turner wrote: That very thought crossed my mind, but I'm not sure how that could happen. The unit is on a dedicated 115V circuit tied to a single-pole breaker. Where would the possibility exist for the neutral to become hot? In the breaker box? It happens all the time. |
Blew another damn transformer on my Trane XB80
It does sound like there is unidentified problem. As the
fellows on alt hvac are often heard to say "replace the thermostat". -- Christopher A. Young Learn more about Jesus www.lds.org .. wrote in message ... I'd venture something is already wrong... -- I'd agree. Responding to his first post and before he put this latest transformer in I recommended measuring how many amps are being drawn on the low voltage side. This is electricity 101. So, he comes here asking for advice and instead of listening, he justs puts another transformer in and blows it too..... Go figure. Time to either get educated or hire a pro. |
Blew another damn transformer on my Trane XB80
Agree, sounds like electrical problem, and the OP isn't
quite skilled enough to find it. -- Christopher A. Young Learn more about Jesus www.lds.org .. wrote in message ... The problem with that theory is that the 120V circuit that supplies power to the transformer also powers the rest of the furnace, ie the inducer blower, main blower, etc. If it were getting 240V, one would think by now one of those other components would have failed. Also, with 240V it would be delivering 48V to the logic board, which one would think would have opened a fuse on it or destroyed some electronics by now. I can't say I can make much sense of what is going on either. But until someone with some basic electric skills capable of taking some measurements looks at it, I doubt we're gonna fix it by remote analysis. |
Blew another damn transformer on my Trane XB80
Doesn't have to be....
-- Christopher A. Young Learn more about Jesus www.lds.org .. "Steve Turner" wrote in message ... there are no 220 circuits running anywhere near that area of the house. Thanks. |
Blew another damn transformer on my Trane XB80
On 4/8/2011 8:52 PM, Steve Turner wrote:
A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): It would seem to me that you are going to have to get yet another transformer. Put a fuse on the primary, 1/2 A I would think. Slow blow, perhaps less. Then I'd check a couple things. Note where it says that the integrated controller is polarity sensitive. Check to make sure it is correct. Then I would look to see if anything looks overheated on the integrated controller. I doubt it is any of the motors as those probably all run on line voltage. Jeff http://www.trane.com/webcache/un/fur...7_04012009.pdf |
Blew another damn transformer on my Trane XB80
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Blew another damn transformer on my Trane XB80
On 4/8/2011 8:52 PM, Steve Turner wrote:
A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. I never got a real chance to test out the system after installing this third transformer. We had cool weather for several days, and I never tried to force the system to come on so I could monitor it; that was probably a mistake. Unfortunately, I was also absent from the premises during the extended times when the unit was most likely operational, so that didn't help either. However, my family tells me that it WAS working and cooling the house rather nicely, for at least a day, perhaps two. I'm getting 115V in all the right places, so it doesn't look like an over-voltage condition to me. Perhaps it's an overheating condition? It looks to me like the only real load on this circuit is the blower motor; could the motor be causing this? The blower spins freely when I turn it by hand. Start capacitor on the motor maybe? Relay on the control board perhaps? Steve, If you are not comfortable with taking current measurements, or do not have an ammeter, or do not wish to sit there waiting for some unusual condition which is drawing too much current, you could temporarily install an in-line fuse holder and automotive cartridge fuse rated at or above the secondary side amperage which the transformer is rated. With this fuse installed on the secondary side, in series with the load, you could then determine if the load is indeed drawing too much current from the secondary and burning out the transformer, versus primary side excess voltage being the problem. A rough guess would be that the contactor coil should maybe be drawing about a quarter to a half an amp of current at 24V. The transformer secondary should not need to source a lot more than that amount of current to provide adequate power to the coil of the contactor. Fuses are a lot cheaper than transformers...... There may be an intermittent short in the wiring to the coil, a short in the coil itself, a breakdown of the coil insulation allowing a short to ground when the coil heats up or cools or vibrates, etc. Smarty |
Blew another damn transformer on my Trane XB80
On 4/9/2011 2:58 PM, A. Baum wrote:
On Sat, 09 Apr 2011 14:41:05 -0500, Steve Turner wrote: But measuring and understanding the ramifications of current (amperage) is where I get a little fuzzy. Would you help me out? That's why I came here. I advised you the last time to measure the 24 volt circuit amperage draw and convert that to the specs (volt-amps) of the transformer. If the draw is out of bounds of the specs then the 24 volt circuit is the problem. You can't put a band-aid on a bullet wound. Yes, you did, and thanks for the suggestion. I've never used my meter to measure amperage before, and I don't know how to do that conversion, but I will study up on it. |
Blew another damn transformer on my Trane XB80
On 4/9/2011 12:43 PM, Tony Miklos wrote:
On 4/9/2011 11:55 AM, Steve Turner wrote: On 4/9/2011 10:29 AM, The Daring Dufas wrote: On 4/9/2011 8:30 AM, Tony Miklos wrote: On 4/9/2011 12:38 AM, David Nebenzahl wrote: On 4/8/2011 8:22 PM Steve Turner spake thus: On 4/8/2011 7:58 PM, David Nebenzahl wrote: On 4/8/2011 5:52 PM Steve Turner spake thus: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. How 'bout installing an in-line fuse next time you replace the xfmr? I'd put it on the secondary side. That way, if there is an overload, the fuse will blow instead. Thinking maybe I should spring for a transformer with a manual reset, like this one: http://www.pexsupply.com/White-Rodge...unt-14937000-p Would that protect me from having to replace the damn transformer every time? It looks like the circuit breaker is on the 24V output side; I'm a little fuzzy on how that would protect the input side of the transformer...? Why in the world would you think you need to protect the primary side? Look at the picture. The primary side has been overheated, the secondary side looks fine. Looks like an over voltage problem to me. I wonder if our intrepid OP has done the basics involved in troubleshooting instead of flitting around from place to place? In the case of a power problem, you always start at the source by measuring voltage and current. It could be a very simple problem like a bit of insulation skinned off a thermostat wire that only shorts out when everything is buttoned up and vibration from the running unit causes the short circuit. If you ever watched the TV program MASH, you would see the surgeons run the intestines looking for a nick in the wall of the organ. Wiring is the same way sometimes. I'll inspect the wiring and often find a small cut or tiny area where insulation is missing and sometimes the wire is bent over a sharp edge of the cabinet where it's fine until you close things up. I wonder if the supply voltage to the transformer is what it's supposed to be? Most domestic household air handler/furnaces are powered by 120vac but some may require 240vac if there are electric heat strips. I would check the voltage feeding the transformer first. TDD Yes, I've done all those things. The supply voltage is fine. I've inspected the wiring at great length and can find no evidence of problems; it all looks pristine. It's a gas furnace, and there are no 220 circuits running anywhere near that area of the house. Thanks. It doesn't take any 220 (240) circuits to cause that. I think someone already mentioned the possibility of a bad neutral connection allowing the supply voltage to shoot up. TDD |
Blew another damn transformer on my Trane XB80
On 4/9/2011 3:43 PM, Smarty wrote:
On 4/8/2011 8:52 PM, Steve Turner wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. I never got a real chance to test out the system after installing this third transformer. We had cool weather for several days, and I never tried to force the system to come on so I could monitor it; that was probably a mistake. Unfortunately, I was also absent from the premises during the extended times when the unit was most likely operational, so that didn't help either. However, my family tells me that it WAS working and cooling the house rather nicely, for at least a day, perhaps two. I'm getting 115V in all the right places, so it doesn't look like an over-voltage condition to me. Perhaps it's an overheating condition? It looks to me like the only real load on this circuit is the blower motor; could the motor be causing this? The blower spins freely when I turn it by hand. Start capacitor on the motor maybe? Relay on the control board perhaps? Steve, If you are not comfortable with taking current measurements, or do not have an ammeter, or do not wish to sit there waiting for some unusual condition which is drawing too much current, you could temporarily install an in-line fuse holder and automotive cartridge fuse rated at or above the secondary side amperage which the transformer is rated. With this fuse installed on the secondary side, in series with the load, you could then determine if the load is indeed drawing too much current from the secondary and burning out the transformer, versus primary side excess voltage being the problem. A rough guess would be that the contactor coil should maybe be drawing about a quarter to a half an amp of current at 24V. The transformer secondary should not need to source a lot more than that amount of current to provide adequate power to the coil of the contactor. Fuses are a lot cheaper than transformers...... There may be an intermittent short in the wiring to the coil, a short in the coil itself, a breakdown of the coil insulation allowing a short to ground when the coil heats up or cools or vibrates, etc. Smarty Yes Smarty, I would very much like to try this approach because I don't want to zap any more transformers. Lots of people have suggested it, but there appear to be more types of fuses than there are insects, and I have no idea what *exact* type to look for. That's why I asked earlier in this thread if this particular transformer: http://www.pexsupply.com/White-Rodge...unt-14937000-p with a built-in manual reset would be a much cleaner solution that serves the same purpose, but I got no responses. The specs on the original transformer we Class 2, 115V primary (60hz), 24V (35VA) secondary. Any chance you could point me to some _exact_ fuse solutions for this application? There's a virtual six-pack of beer in it for you. :-) |
Blew another damn transformer on my Trane XB80
On 4/9/2011 2:04 PM Steve Turner spake thus:
On 4/9/2011 2:58 PM, A. Baum wrote: On Sat, 09 Apr 2011 14:41:05 -0500, Steve Turner wrote: But measuring and understanding the ramifications of current (amperage) is where I get a little fuzzy. Would you help me out? That's why I came here. I advised you the last time to measure the 24 volt circuit amperage draw and convert that to the specs (volt-amps) of the transformer. If the draw is out of bounds of the specs then the 24 volt circuit is the problem. You can't put a band-aid on a bullet wound. Yes, you did, and thanks for the suggestion. I've never used my meter to measure amperage before, and I don't know how to do that conversion, but I will study up on it. It's not a "conversion". To measure current (which, properly speaking, is what you're measuring, not "amperage"), you have to break the circuit and put the ammeter in series with the circuit, so that all the current goes through the meter. (As opposed to measuring voltage, where you put the meter *across*, or in parallel with, the thing whose voltage you want to know.) In your case, since you want to see how much current is being drawn from the transformer, you'd put the ammeter between one of the transformer secondary leads (doesn't matter which one) and whatever wire from your unit that's supposed to connect to that lead. Since you're measuring AC current, you'll need an AC ammeter, which rules out most digital multimeters, which only are designed to measure DC current. Not sure where you'd (quickly, easily) get an AC meter. Maybe others can suggest? But that's how you do it. -- The current state of literacy in our advanced civilization: yo wassup nuttin wan2 hang k where here k l8tr by - from Usenet (what's *that*?) |
Blew another damn transformer on my Trane XB80
On Fri, 08 Apr 2011 19:52:06 -0500, Steve Turner
wrote: A continuation of the "Why does the 115V-24V transformer keep blowing on my Trane XB80?" discussion I started on 04/02/2011. Yep, My A/C unit blew another transformer. Pictures (and wiring diagram) he http://www.flickr.com/photos/bbqboye...7626457562742/ Trane's manual for the unit is here (for perhaps better viewing of the wiring diagrams that I also copied to my above flickr site as jpg images): http://www.trane.com/webcache/un/fur...7_04012009.pdf As you can probably see in the pictures, there is visible charring of the 115V leads going into the transformer, and of course the 115V circuit is open (again). If you didn't see my first thread, this is the third transformer the unit has blown. In the previous discussion, it was discussed that perhaps the first one just blew because of old age (6 years), and the second blew because it wasn't a proper replacement (poor quality, made in China, etc.). This third unit is most certainly a proper replacement, and it's most certainly indicative of a real problem I have somewhere else in the unit. I didn't see any such charring on the previous two units, at least not like this. I never got a real chance to test out the system after installing this third transformer. We had cool weather for several days, and I never tried to force the system to come on so I could monitor it; that was probably a mistake. Unfortunately, I was also absent from the premises during the extended times when the unit was most likely operational, so that didn't help either. However, my family tells me that it WAS working and cooling the house rather nicely, for at least a day, perhaps two. I'm getting 115V in all the right places, so it doesn't look like an over-voltage condition to me. Perhaps it's an overheating condition? It looks to me like the only real load on this circuit is the blower motor; could the motor be causing this? The blower spins freely when I turn it by hand. Start capacitor on the motor maybe? Relay on the control board perhaps? The blower motor is NOT running on the 24 volt transformer, so will have NO effect on the transformer. You NEED to fuse the secondary - then IF it is an overload problem you will just pop the fuse, and not the transformer. 24 volt, 35 VA = 1,5 amp FAST BLOW fuse. If the fuse does not blow and the transformer does, it PROVES, almost beyond a doubt, that you have bad luck getting a good transformer. The other option is to closely monitor the primary current and see what you have. |
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