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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#41
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55 horsepower motor can run on 25kva transformer
On Fri, 04 Jul 2014 05:58:35 -0700, Larry Jaques
wrote: On Fri, 04 Jul 2014 02:40:32 -0700, Gunner Asch wrote: On Thu, 03 Jul 2014 16:05:41 -0700, Larry Jaques wrote: On Thu, 03 Jul 2014 18:59:49 +0800, DTJ wrote: On 03-Jul-14 5:04 PM, wrote: Hi.i have a simple question.i just want to.knw that can 55horse power motorr machine can run on 25kva transformer.waiting for ur answer.thanks does this help? http://www.dieselserviceandsupply.co...alculator.aspx Interesting. It takes 166.187kvA to directly run a 55hp motor. The 26kva xfmr couldn't quite run a 7hp motor. Good page, bookmarked! It might..might run it..but it certainly wont start it. Put a load on it...poof! For that sized motor..45 KVA is a requirement According to the bookmarked site's calc, it takes 166.187kva to run that motor properly. Where did you get the 45kva number? the 7.5hp motor..not the 55 hp one - "[F]ar from being the Great Satan, I would say that we are the Great Protector. We have sent men and women from the armed forces of the United States to other parts of the world throughout the past century to put down oppression. We defeated Fascism. We defeated Communism. We saved Europe in World War I and World War II. We were willing to do it, glad to do it. We went to Korea. We went to Vietnam. All in the interest of preserving the rights of people. And when all those conflicts were over, what did we do? Did we stay and conquer? Did we say, "Okay, we defeated Germany. Now Germany belongs to us? We defeated Japan, so Japan belongs to us"? No. What did we do? We built them up. We gave them democratic systems which they have embraced totally to their soul. And did we ask for any land? No. The only land we ever asked for was enough land to bury our dead." General Colin Powell |
#42
Posted to rec.crafts.metalworking
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55 horsepower motor can run on 25kva transformer
"Larry Jaques" wrote in message
... On Fri, 04 Jul 2014 02:40:32 -0700, Gunner Asch wrote: On Thu, 03 Jul 2014 16:05:41 -0700, Larry Jaques wrote: On Thu, 03 Jul 2014 18:59:49 +0800, DTJ wrote: On 03-Jul-14 5:04 PM, wrote: Hi.i have a simple question.i just want to.knw that can 55horse power motorr machine can run on 25kva transformer.waiting for ur answer.thanks does this help? http://www.dieselserviceandsupply.co...alculator.aspx Interesting. It takes 166.187kvA to directly run a 55hp motor. The 26kva xfmr couldn't quite run a 7hp motor. Good page, bookmarked! It might..might run it..but it certainly wont start it. Put a load on it...poof! For that sized motor..45 KVA is a requirement According to the bookmarked site's calc, it takes 166.187kva to run that motor properly. Where did you get the 45kva number? The calculator gives 166.187 KVA for a GENSET that will start the motor. A transformer has the capacity of the grid behind it to provide the starting surge, a genny needs to provide the peak current all by itself. -jsw |
#43
Posted to rec.crafts.metalworking
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55 horsepower motor can run on 25kva transformer
On Fri, 4 Jul 2014 19:24:22 -0400, "Jim Wilkins"
wrote: "Larry Jaques" wrote in message .. . On Fri, 04 Jul 2014 02:40:32 -0700, Gunner Asch wrote: On Thu, 03 Jul 2014 16:05:41 -0700, Larry Jaques wrote: On Thu, 03 Jul 2014 18:59:49 +0800, DTJ wrote: On 03-Jul-14 5:04 PM, wrote: Hi.i have a simple question.i just want to.knw that can 55horse power motorr machine can run on 25kva transformer.waiting for ur answer.thanks does this help? http://www.dieselserviceandsupply.co...alculator.aspx Interesting. It takes 166.187kvA to directly run a 55hp motor. The 26kva xfmr couldn't quite run a 7hp motor. Good page, bookmarked! It might..might run it..but it certainly wont start it. Put a load on it...poof! For that sized motor..45 KVA is a requirement According to the bookmarked site's calc, it takes 166.187kva to run that motor properly. Where did you get the 45kva number? The calculator gives 166.187 KVA for a GENSET that will start the motor. A transformer has the capacity of the grid behind it to provide the starting surge, a genny needs to provide the peak current all by itself. Oh, you're right. I focused too much on the translation figures. -- The goal to strive for is a poor government but a rich people. --Andrew Johnson |
#44
Posted to rec.crafts.metalworking
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55 horsepower motor can run on 25kva transformer
"Jim Wilkins" wrote in message ...
"Larry Jaques" wrote in message .. . For that sized motor..45 KVA is a requirement According to the bookmarked site's calc, it takes 166.187kva to run that motor properly. Where did you get the 45kva number? The calculator gives 166.187 KVA for a GENSET that will start the motor. A transformer has the capacity of the grid behind it to provide the starting surge, a genny needs to provide the peak current all by itself. -jsw I wonder if an AC drive would be of any benefit? I'm guessing the used market for 55HP drives may not have as much demand as smaller home shop size drives. My 10HP drive on my 7.5HP lathe runs around 13A at idle on the motor side but only draws 5A from the outlet. If my understanding is correct, the 13A is mostly apparent power while the 5A is more representative of the true power. Perhaps a drive would do better at getting close to 25KW from the 25KVA transformer and handle the VAR on the motor side. RogerN |
#45
Posted to rec.crafts.metalworking
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55 horsepower motor can run on 25kva transformer
On Fri, 4 Jul 2014 19:24:22 -0400, "Jim Wilkins"
wrote: "Larry Jaques" wrote in message .. . On Fri, 04 Jul 2014 02:40:32 -0700, Gunner Asch wrote: On Thu, 03 Jul 2014 16:05:41 -0700, Larry Jaques wrote: On Thu, 03 Jul 2014 18:59:49 +0800, DTJ wrote: On 03-Jul-14 5:04 PM, wrote: Hi.i have a simple question.i just want to.knw that can 55horse power motorr machine can run on 25kva transformer.waiting for ur answer.thanks does this help? http://www.dieselserviceandsupply.co...alculator.aspx Interesting. It takes 166.187kvA to directly run a 55hp motor. The 26kva xfmr couldn't quite run a 7hp motor. Good page, bookmarked! It might..might run it..but it certainly wont start it. Put a load on it...poof! For that sized motor..45 KVA is a requirement According to the bookmarked site's calc, it takes 166.187kva to run that motor properly. Where did you get the 45kva number? The calculator gives 166.187 KVA for a GENSET that will start the motor. A transformer has the capacity of the grid behind it to provide the starting surge, a genny needs to provide the peak current all by itself. -jsw for the 7.5hp motor - "[F]ar from being the Great Satan, I would say that we are the Great Protector. We have sent men and women from the armed forces of the United States to other parts of the world throughout the past century to put down oppression. We defeated Fascism. We defeated Communism. We saved Europe in World War I and World War II. We were willing to do it, glad to do it. We went to Korea. We went to Vietnam. All in the interest of preserving the rights of people. And when all those conflicts were over, what did we do? Did we stay and conquer? Did we say, "Okay, we defeated Germany. Now Germany belongs to us? We defeated Japan, so Japan belongs to us"? No. What did we do? We built them up. We gave them democratic systems which they have embraced totally to their soul. And did we ask for any land? No. The only land we ever asked for was enough land to bury our dead." General Colin Powell |
#46
Posted to rec.crafts.metalworking
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55 horsepower motor can run on 25kva transformer
Tom Gardner wrote: Don't forget "Nonsensical"! We'll never forget you, Tom! -- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
#47
Posted to rec.crafts.metalworking
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55 horsepower motor can run on 25kva transformer
On Wed, 09 Jul 2014 13:37:09 -0400, "Michael A. Terrell"
wrote: Tom Gardner wrote: Don't forget "Nonsensical"! We'll never forget you, Tom! No matter -how- hard we try, huh? bseg -- Liberalism is a pathology. |
#48
Posted to rec.crafts.metalworking
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What size motor can I start with a 45 kVA transformer
On Thursday, January 5, 2012 at 9:27:16 AM UTC+5, Ignoramus8679 wrote:
I understand that there is a bit of fudge factors involved, but I want to know, approximately what size motors (with a usual load, like a compressor or a lathe) can I start with a 45 kVA transformer feeding it. No soft start of course. Thanks Hey Need some help. I have a 50 kva Transformer. Hpw do calculate how many of the given below machines I can run? Its a 4 head imoulder Powers engines 1) Lower head 7,5 kW - 8000 RPM 2) Right head 7,5 kW - 8000 RPM Power Lock system 3) Left head 7,5 kW - 8000 RPM Power Lock system 4) Overhead 7.5 kW - 8000 RPM 5) Lower head 5,5 kW - 8000 RPM -Installed power of 52 kW Feed motor with 4 kW Motor height adjustment 0,55 kW |
#50
Posted to rec.crafts.metalworking
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55 horsepower motor can run on 25kva transformer
On Thursday, July 3, 2014 at 3:47:08 PM UTC-7, Jon Elson wrote:
wrote: Hi.i have a simple question.i just want to.knw that can 55horse power motorr machine can run on 25kva transformer But, induction motors draw a very lagging power factor at light load. Thus, their current doesn't change very much from idle to full load, but the phase angle of the current changes dramatically. At idle, the current is at least 75% of full rated load current,... So, under light load, the POWER demand of the motor will be fairly small, but the current will exceed the current rating of the transformer. Not true, really; the back-emf is being completely neglected here, and under light load, only some REAL power (a phase shift with respect to the 'idle' reactionary power) is drawn. The current at idle is very small, and out of phase. At light load, it's STILL very small, but closer to in phase. Light load doesn't increase the ohmic losses at all. It takes substantial load, and nearly in-phase current and voltage, before the motor starts to stall (and draws high current and melts the wiring). At startup, the motor is aways 'near stall', which is why such motors don't turn on with a simple switch, but have a sequenced start process. |
#51
Posted to rec.crafts.metalworking
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55 horsepower motor can run on 25kva transformer
whit3rd wrote:
On Thursday, July 3, 2014 at 3:47:08 PM UTC-7, Jon Elson wrote: wrote: Hi.i have a simple question.i just want to.knw that can 55horse power motorr machine can run on 25kva transformer But, induction motors draw a very lagging power factor at light load. Thus, their current doesn't change very much from idle to full load, but the phase angle of the current changes dramatically. At idle, the current is at least 75% of full rated load current,... So, under light load, the POWER demand of the motor will be fairly small, but the current will exceed the current rating of the transformer. Not true, really; the back-emf is being completely neglected here, and under light load, only some REAL power (a phase shift with respect to the 'idle' reactionary power) is drawn. The current at idle is very small, and out of phase. At light load, it's STILL very small, but closer to in phase. Light load doesn't increase the ohmic losses at all. This is an old thread, don't know where it popped up from. Well, the guy wanted to run a 55 HP motor on a 25 KVA transformer. Not clear what voltage we're talking about, but most likely 480 for a motor that large. Roughly, the rated line current for a typical 480 V 55 Hp motor would be about 90 A. At idle, such a motor would draw at least 50 A, although the power factor would be close to zero. So, the real power draw would be small, but the line current would still be pretty large, and close to 40 KVA, WAY above the rating of the transformer. Yes, for a quick test, the transformer would handle it, but you'd not get away with actually running the machine that way. Possibly, with a big bank of power factor correcting caps, it would be OK. Jon |
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