Toroidal mains Tx inrush limiter - retrofit
 

This 300W amp blows correct T3.15A fuses every now and then at sw on. The
owner left in the last one so I can see it is just "tired" , neat break and
2 constituent parts of fuse wire remaining.

Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush
thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam
leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Other
than poor physical integrity of the lead "welds" to the body (like disc
ceramic cap) - will mount on small high temp board and wire into the neutral
side of the wiring, with plenty of clear air space around.

Other than zero crossing Triac sub-cicuit to delay sw off, not creating
ferrite core residual magnetism, and delayed switching on also, any other
ways around this phenomenon other than bad practise uprating of the mains
fuse? Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?

Toroidal mains Tx inrush limiter - retrofit
 

In article , N_Cook
writes

This 300W amp blows correct T3.15A fuses every now and then at sw on. The
owner left in the last one so I can see it is just "tired" , neat break and
2 constituent parts of fuse wire remaining.

We have a similar problem at work with cryogenic coolers, which are more
or less like a fridge - a compressor and heat exchanger. Like you say,
the fuse doesn't blow, just parts cleanly due to inrush surge at switch
on.

Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush
thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam
leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel.

Don't see why not. Or a 1 ohm wirewound resistor which will dissipate
3.15W at peak, so use a 5W one. Mount it in free air, of course.

will mount on small high temp board and wire into the neutral
side of the wiring,

Why the neutral? Just curious.

Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?

I would say they are unsafe for use on mains, simply because they
reconnect the current when they heal. If there is an actual fault in
the equipment rather than the inrush current blowing the fuse and
disabling the supply permanently, it could lead to a fire.

--
Mike Tomlinson

Toroidal mains Tx inrush limiter - retrofit
 

On Wed, 30 Mar 2011 13:07:48 +0100, N_Cook wrote:

This 300W amp blows correct T3.15A fuses every now and then at sw on.
The owner left in the last one so I can see it is just "tired" , neat
break and 2 constituent parts of fuse wire remaining.

Slo Blow?



--
Live Fast Die Young, Leave A Pretty Corpse

Toroidal mains Tx inrush limiter - retrofit
 

In article , Meat Plow
writes

Slo Blow?

He is fitting slo blo, it's what the T in "T3.15A" means.

--
Mike Tomlinson

Toroidal mains Tx inrush limiter - retrofit
 

"N_Cook" wrote in message
...
This 300W amp blows correct T3.15A fuses every now and then at sw on. The
owner left in the last one so I can see it is just "tired" , neat break
and
2 constituent parts of fuse wire remaining.

Any issues concerning putting in an ex pc SMPS 450W, 250V land mains
inrush
thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam
leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel.
Other
than poor physical integrity of the lead "welds" to the body (like disc
ceramic cap) - will mount on small high temp board and wire into the
neutral
side of the wiring, with plenty of clear air space around.

Other than zero crossing Triac sub-cicuit to delay sw off, not creating
ferrite core residual magnetism, and delayed switching on also, any other
ways around this phenomenon other than bad practise uprating of the mains
fuse? Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?




I've had a few bits of gear for repair that just seem to have an under-rated
fuse. e.g. Mackie SR1530.
Try a T4 instead.

I even had a Marshall here that had (according to Marshall) the wrong value
fuse designed in. It was doing my head in for ages until I phoned Marshall
about it.
They sent me an uprated fuse and stickers to place on the PCB showing the
uprated value.



Gareth.

Toroidal mains Tx inrush limiter - retrofit
 

Mike Tomlinson wrote in message
...
In article , N_Cook
writes

This 300W amp blows correct T3.15A fuses every now and then at sw on. The
owner left in the last one so I can see it is just "tired" , neat break
and
2 constituent parts of fuse wire remaining.

We have a similar problem at work with cryogenic coolers, which are more
or less like a fridge - a compressor and heat exchanger. Like you say,
the fuse doesn't blow, just parts cleanly due to inrush surge at switch
on.

Any issues concerning putting in an ex pc SMPS 450W, 250V land mains
inrush
thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam
leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel.

Don't see why not. Or a 1 ohm wirewound resistor which will dissipate
3.15W at peak, so use a 5W one. Mount it in free air, of course.

will mount on small high temp board and wire into the neutral
side of the wiring,

Why the neutral? Just curious.

Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?

I would say they are unsafe for use on mains, simply because they
reconnect the current when they heal. If there is an actual fault in
the equipment rather than the inrush current blowing the fuse and
disabling the supply permanently, it could lead to a fire.

--
Mike Tomlinson


An engineer I know with IBM Hursley has the same problem with large toroid
Tx on some research kit, he personally was not aware of the phenomenon of
random remnant magnetisation at switch off, then right/wrong polarity
mutually coupled across "adds" to the inrush current , until he asked me if
I knew.

Some more data on this thermistor , green and marked CCK but no info found
Passing DC through it , stabilizes at 2.7R with 1.2V across it so 3.2W ,
..44R and measuring 115 deg C via IR "pyrometer"

Toroidal mains Tx inrush limiter - retrofit
 

2.7 amp , not 2.7R

Toroidal mains Tx inrush limiter - retrofit
 

On Wed, 30 Mar 2011 14:56:24 +0100, Mike Tomlinson wrote:

In article , Meat Plow
writes

Slo Blow?

He is fitting slo blo, it's what the T in "T3.15A" means.

Thought the T mean the size.



--
Live Fast Die Young, Leave A Pretty Corpse

Toroidal mains Tx inrush limiter - retrofit
 

In article , Meat Plow
writes

Thought the T mean the size.

T for Time delay :o)

--
(\__/)
(='.'=)
(")_(")

Toroidal mains Tx inrush limiter - retrofit
 

On Wed, 30 Mar 2011 18:52:48 +0100, Mike Tomlinson wrote:

In article , Meat Plow
writes

Thought the T mean the size.

T for Time delay :o)

I just thought of something. Ambient temperature does affect current
carrying capability. Maybe this has some influence on Cook's problem?
High ambient temperature over a period of time weakens the fuse material
and after current influx causes the fuse core to 'twitch' many times it
finally breaks. Not unlike a light bulb.



--
Live Fast Die Young, Leave A Pretty Corpse

Toroidal mains Tx inrush limiter - retrofit
 

By the way,

What's the antithesis of Occam's razor?

Toroidal mains Tx inrush limiter - retrofit
 

Religious superstition?

Toroidal mains Tx inrush limiter - retrofit
 

On Mar 30, 8:22*am, "Phil Allison" wrote:
"Nutcase ****ing Kook"


***You ridiculous, ****ing nut case *!!!

** ****ing stupid.


***You * *ABSOLUTE * DONKEY'S * ASS !!!


* *** Wot a *COLOSSAL *MORON *!!!


***You ****ing stupid ASS !!!!!!!

..... *Phil

I'm sure I'm one of the very few who haven't plonked you yet and can
actually view any of your posts (and realize that by quoting you I am
actually giving you some exposure), but I have to say that you are one
smooth talker Phil. You must be quite the hit with the ladies.

Edwin

Toroidal mains Tx inrush limiter - retrofit
 

"Stroonz"

** Bugger off - IMBECILE

Toroidal mains Tx inrush limiter - retrofit
 

"Mike Tomlinson"


We have a similar problem at work with cryogenic coolers, which are more
or less like a fridge - a compressor and heat exchanger. Like you say,
the fuse doesn't blow, just parts cleanly due to inrush surge at switch
on.


** What absolute crap !!!

The magnetic inush suge of a toroidal tranny plus filter caps charging will
easily SPLAT an undesized "slo blo" or " fast " fuse completely.


Don't see why not. Or a 1 ohm wirewound resistor which will dissipate
3.15W at peak, so use a 5W one


** ROTFL - what difference is 1 ohm gonna make ??


will mount on small high temp board and wire into the neutral


Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?

I would say they are unsafe for use on mains, simply because they
reconnect the current when they heal. If there is an actual fault in
the equipment rather than the inrush current blowing the fuse and
disabling the supply permanently, it could lead to a fire.


** Polyswitches all start of with a very low resistane then go high after
some time at high current - mains voltage rated examples do not exist.



.... Phil

Toroidal mains Tx inrush limiter - retrofit
 

"Nutcase ****ing Kook "

An engineer I know with IBM Hursley has the same problem with large toroid
Tx on some research kit, he personally was not aware of the phenomenon of
random remnant magnetisation at switch off, then right/wrong polarity
mutually coupled across "adds" to the inrush current , until he asked me
if

** Shame you have totally mis-informed him.

I knew.


** You know absolutely NOTHING !!



..... Phil

Toroidal mains Tx inrush limiter - retrofit
 

"Mike Tomlinson"

T for Time delay :o)


** The "T" stamp on fuses stands for the German word " Trage" = lazy.



...... Phil

Toroidal mains Tx inrush limiter - retrofit
 

"Gareth Magennis"


What's the antithesis of Occam's razor?

** Conspiracy theories - cos they always involve many unnecessary,
unsupported and improbable assumptions.



..... Phil

Toroidal mains Tx inrush limiter - retrofit
 

Polyswitches all start of with a very low resistance,
then go high after some time at high current --
mains-voltage rated examples do not exist.

Then what causes my bulk eraser to shut off when it overheats -- then come
back when it cools off?

Toroidal mains Tx inrush limiter - retrofit
 

Hehe... I think you and I are the only two folk who can see your
posts Phil. Don't worry, I won't plonk you. There is precious little
else on the web that's as interesting as you. Make sure you come up
with a real zinger for me!!!!

Edwin

Toroidal mains Tx inrush limiter - retrofit
 

"William Sommer******"

Then what causes my bulk eraser to shut off when it overheats -- then come
back when it cools off?


** Have a ****ing look.




..... Phil

Toroidal mains Tx inrush limiter - retrofit
 

On 3/30/2011 7:07 AM, N_Cook wrote:
This 300W amp blows correct T3.15A fuses every now and then at sw on. The
owner left in the last one so I can see it is just "tired" , neat break and
2 constituent parts of fuse wire remaining.

Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush
thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam
leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Other
than poor physical integrity of the lead "welds" to the body (like disc
ceramic cap) - will mount on small high temp board and wire into the neutral
side of the wiring, with plenty of clear air space around.

Other than zero crossing Triac sub-cicuit to delay sw off, not creating
ferrite core residual magnetism, and delayed switching on also, any other
ways around this phenomenon other than bad practise uprating of the mains
fuse? Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?



http://www.ametherm.com/inrush-curre...t-limiter.html

bob

Toroidal mains Tx inrush limiter - retrofit
 

"boob errs = Google Monkey "

http://www.ametherm.com/inrush-curre...t-limiter.html



** Wot a load of utterly irrelevant, mindless drivel.

Musta been written by a marketing puke.



...... Phil

Toroidal mains Tx inrush limiter - retrofit
 

On 3/30/2011 9:13 PM, bob urz wrote:
O
Other than zero crossing Triac sub-cicuit to delay sw off, not creating
ferrite core residual magnetism, and delayed switching on also, any other
ways around this phenomenon other than bad practise uprating of the mains
fuse? Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?



http://www.ametherm.com/inrush-curre...t-limiter.html


bob

http://www.ametherm.com/inrush-curre...h-current.html

Toroidal mains Tx inrush limiter - retrofit
 

Gareth Magennis wrote in message
...
By the way,

What's the antithesis of Occam's razor?





dunno but talking to a philosopher last week for his take on occam's razor
,
he put me right in that it is a mistranslation of Occam's raison ...
I run science talks locally and he will be talking on the philosophy of
science, Nicomachean Ethics, Occam's whatever etc
series details
http://www.diverse.4mg.com/scicaf.htm

Toroidal mains Tx inrush limiter - retrofit
 

"Nutcase ****ing Kook"


dunno but talking to a philosopher last week for his take on occam's
razor
,
he put me right in that it is a mistranslation of Occam's raison ...

** Utter bull****.

Kook is such a retarded ****wit, god know how he remembers to ****.



...... Phil

Toroidal mains Tx inrush limiter - retrofit
 

In article
s.com, Stroonz writes

You must be quite the hit with the ladies.

Given that he seems to be obsessed with ass, I suspect he probably hangs
out in his local gay leather bar.

--
Mike Tomlinson

Toroidal mains Tx inrush limiter - retrofit
 

In article , William Sommerwerck
writes

Then what causes my bulk eraser to shut off when it overheats -- then come
back when it cools off?

That's a resettable *thermal* fuse, NOT a fuse designed for overcurrent
protection.

--
Mike Tomlinson

Toroidal mains Tx inrush limiter - retrofit
 

In article , Gareth Magennis
writes

What's the antithesis of Occam's razor?

Occam's beard?

--
Mike Tomlinson

Toroidal mains Tx inrush limiter - retrofit
 

"Mike Tomlinson"


** What a BORING know nothing, ****wit bull**** artist.

The LESS you know about a topic - the MORE you feel compelled to talk
******** about it.

I call that sort of rampant narcissism: " pommy disease ".

Wot a shame it ain't fatal.



..... Phil

Toroidal mains Tx inrush limiter - retrofit
 

"William Sommer******"

I love the fact I have a name that so lends itself to stupid wordplay.


Then what causes my bulk eraser to shut off when it overheats
-- then come back when it cools off?

** Have a ****ing look.

I especially love the way you squirm when backed into a corner.

Toroidal mains Tx inrush limiter - retrofit
 

Then what causes my bulk eraser to shut off when it overheats
-- then come back when it cools off?

That's a resettable *thermal* fuse, NOT a fuse designed for
overcurrent protection.

I had always thought that at least some polyfuses /were/ resettable.
Regardless, thanks for the answer.

Toroidal mains Tx inrush limiter - retrofit
 

"William Sommer****** is a Lying **** "

I love the fact I have a name that so lends itself to stupid wordplay.


Then what causes my bulk eraser to shut off when it overheats
-- then come back when it cools off?


** Have a ****ing look !!!!!!!!!!!!!

You STINKING, AUTISTIC ARSEHOLE !!!

Toroidal mains Tx inrush limiter - retrofit
 

"William Sommer******"

Some Bull****ting Pommy ****wit.

Then what causes my bulk eraser to shut off when it overheats
-- then come back when it cools off?

That's a resettable *thermal* fuse, NOT a fuse designed for
overcurrent protection.

I had always thought that at least some polyfuses /were/ resettable.


** A " PolySwitch " is self resetting and so is a " Polyfuse".

Same basic device.

You ****ing RETARD !!!!!!!




..... Phil

Toroidal mains Tx inrush limiter - retrofit
 

On 3/30/2011 8:07 AM, N_Cook wrote:
This 300W amp blows correct T3.15A fuses every now and then at sw on. The
owner left in the last one so I can see it is just "tired" , neat break and
2 constituent parts of fuse wire remaining.

Any issues concerning putting in an ex pc SMPS 450W, 250V land mains inrush
thermistor, unknown specs, other than 14mm diameter, 4mm wide , 1mm diam
leads, 8R cold , 1R after 20 seconds touched by soldering iron barrel. Other
than poor physical integrity of the lead "welds" to the body (like disc
ceramic cap) - will mount on small high temp board and wire into the neutral
side of the wiring, with plenty of clear air space around.

Other than zero crossing Triac sub-cicuit to delay sw off, not creating
ferrite core residual magnetism, and delayed switching on also, any other
ways around this phenomenon other than bad practise uprating of the mains
fuse? Are polyswitches used in these circumstances , ie not purely "fuse"
action or generic name for devices specific for this purpose?



Nigel,

Also keep in mind as a possibility that the main filter caps are
getting tired, and a bit leaky, so that if the amp has not been switched
on for a week or 2, it might have abnormally high inrush current as the
caps charge/form back up.

Lastly, the older 'spring wire' fuses seemed more tolerant of the
inrush current compared to the modern chemically treated wire ones.
Maybe use an old style fuse, if you can find one.

It would be helpful if you would mention the make and model of the
product in your posts.

Regards,
Tim Schwartz
Bristol Electronics

Toroidal mains Tx inrush limiter - retrofit
 

On Thu, 31 Mar 2011 20:55:20 +1100, Phil Allison wrote:

What a BORING know nothing, ****wit bull**** artist

Nice self-description.



--
Live Fast Die Young, Leave A Pretty Corpse

Toroidal mains Tx inrush limiter - retrofit
 

Then what causes my bulk eraser to shut off when it overheats
-- then come back when it cools off?

That's a resettable *thermal* fuse, NOT a fuse designed for
overcurrent protection.

I had always thought that at least some polyfuses /were/ resettable.

Polyfuses (in the sense of the term I've always heard used) are
self-resetting, unless you hit 'em so hard that you damage them.

They aren't designed for use at mains voltages/currents, though... at
least, I haven't seen any that are.

The self-resetting thermal "fuses" that you'd find in a bulk eraser or
similar "not intended for a 100% duty cycle - let it cool down!"
device are (I think) of the bimetallic type, somewhat akin to what you
would find in a traditional wall thermostat.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Toroidal mains Tx inrush limiter - retrofit
 

"Tim Schwartz"

Also keep in mind as a possibility that the main filter caps are getting
tired, and a bit leaky, so that if the amp has not been switched on for a
week or 2, it might have abnormally high inrush current as the caps
charge/form back up.

** This is rather fanciful thinking.

An inrush surge ( on a 240V supply) that will take out a T3.15 fuse has to
be in the order of 40 to 50 amps. Toroidal transformers in the range of 220
to 300 VA with rectifiers and filter cap banks will provide such surges
almost every time they are switched on.


Lastly, the older 'spring wire' fuses seemed more tolerant of the inrush
current

** Correct, but hard to find them in other than 3AG size and they are much
more expensive.

compared to the modern chemically treated wire ones.


** Where did you hear this one ??

The ones I use are said to be made from "plated wire" - meaning a thick
tin plating over copper. Some are coil shaped and some are not.


It would be helpful if you would mention the make and model of the product
in your posts.

** Bloody oath it would.

What a colossal ASS Kook is for regularly leaving that crucial info out.


..... Phil

Toroidal mains Tx inrush limiter - retrofit
 

On Thu, 31 Mar 2011 11:12:22 -0700, (Dave Platt) wrote:

Then what causes my bulk eraser to shut off when it overheats
-- then come back when it cools off?

That's a resettable *thermal* fuse, NOT a fuse designed for
overcurrent protection.

I had always thought that at least some polyfuses /were/ resettable.

Polyfuses (in the sense of the term I've always heard used) are
self-resetting, unless you hit 'em so hard that you damage them.

They aren't designed for use at mains voltages/currents, though... at
least, I haven't seen any that are.

Me neither, other thing with polyfuses is that there's approx 2:1 current
difference between trigger point and hold point. I have 16V and 30V poly-
fuses here, generally for 12V or 24V SLA battery powered gear.

The self-resetting thermal "fuses" that you'd find in a bulk eraser or
similar "not intended for a 100% duty cycle - let it cool down!"
device are (I think) of the bimetallic type, somewhat akin to what you
would find in a traditional wall thermostat.

Some are the same thing as used in clothes dryer for thermostat, 100% duty
cycle for years on end ;) Lower temperature for thermostat and a higher
temp one for overheat safety cutout.



Grant.

Toroidal mains Tx inrush limiter - retrofit
 

"Grant"

They aren't designed for use at mains voltages/currents, though... at
least, I haven't seen any that are.

Me neither, other thing with polyfuses is that there's approx 2:1 current
difference between trigger point and hold point.

** That is utterly misleading !!

There are no separate trigger and hold points with PolySwitches.

The makers specs allow for some device to device variation in the actual
current level that will trigger a RANGE of similar devices to change state
and go high resistance.

The max current that fails to trip all examples of a given type is called: "
I Hold ".

The minimum current that will trip all examples of a given type is called: "
I Trip".

" I Trip " is double " I Hold".

For any given device, the trip current is one number.

Once a device has tripped, the current needed to HOLD it in the new state is
a function of the applied voltage and is generally 5 to 20 times less than
the trip current.



..... Phil