Toroidal mains Tx inrush limiter - retrofit
N_Cook
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?
Phil Allison
"Nutcase Fucking Kook"
> This 300W amp.....
** WHAAATTT AAMMMPP !!!!!!!!!!!!!
You ridiculous, fucking nut case !!!
> blows correct T3.15A fuses every now and then at sw on.
** Probably normal.
Use a 4 amp "slo blo" fuse.
> Other than zero crossing Triac sub-cicuit to delay sw off,
** Fucking stupid.
> not creating ferrite core residual magnetism,
** Toroidal mains transformers are NOT ferrite.
You ABSOLUTE DONKEY'S ASS !!!
--------------------------------------------------
> and delayed switching on also,
** Zero crossing switch-on is the WORST thing you can do.
Wot a COLOSSAL MORON !!!
> Are polyswitches used in these circumstances ,
** No.
They have the WRONG resistance / temp characteristic.
You fucking stupid ASS !!!!!!!
..... Phil
Mike Tomlinson
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
Meat Plow
> 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
Mike Tomlinson
<mhyw...@yahoo.com> writes
>Slo Blow?
He is fitting slo blo, it's what the T in "T3.15A" means.
--
Mike Tomlinson
Gareth Magennis
"N_Cook" <div...@tcp.co.uk> wrote in message
news:imv6e9$2gm$1...@dont-email.me...
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.
N_Cook
news:3muFuRBi...@jasper.org.uk...
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"
N_Cook
Meat Plow
> In article <pan.2011.03...@lmao.lol.lol>, Meat Plow
> <mhyw...@yahoo.com> writes
>
>>Slo Blow?
>
> He is fitting slo blo, it's what the T in "T3.15A" means.
Thought the T mean the size.
Mike Tomlinson
<mhyw...@yahoo.com> writes
>Thought the T mean the size.
T for Time delay :o)
--
(\__/)
(='.'=)
(")_(")
Meat Plow
> In article <pan.2011.03...@lmao.lol.lol>, Meat Plow
> <mhyw...@yahoo.com> 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.
Gareth Magennis
What's the antithesis of Occam's razor?
William Sommerwerck
Stroonz
> "Nutcase Fucking Kook"
>
> **You ridiculous, fucking nut case !!!
>
> ** Fucking stupid.
>
> **You ABSOLUTE DONKEY'S ASS !!!
>
> ** Wot a COLOSSAL MORON !!!
>
> **You fucking 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
Phil Allison
"Stroonz"
** Bugger off - IMBECILE
Phil Allison
"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
Phil Allison
"Nutcase fucking 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
Phil Allison
"Mike Tomlinson"
> T for Time delay :o)
** The "T" stamp on fuses stands for the German word " Trage" = lazy.
..... Phil
Phil Allison
"Gareth Magennis"
>
> What's the antithesis of Occam's razor?
** Conspiracy theories - cos they always involve many unnecessary,
unsupported and improbable assumptions.
.... Phil
William Sommerwerck
> 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?
Stroonz
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
Phil Allison
"William Sommerwanker"
> Then what causes my bulk eraser to shut off when it overheats -- then come
> back when it cools off?
>
** Have a fucking look.
.... Phil
bob urz
Phil Allison
"boob errs = Google Monkey "
> http://www.ametherm.com/inrush-current/selecting-an-inrush-current-limiter.html
>
** Wot a load of utterly irrelevant, mindless drivel.
Musta been written by a marketing puke.
..... Phil
bob urz
> 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-current/selecting-an-inrush-current-limiter.html
>
>
> bob
http://www.ametherm.com/inrush-current/transformer-inrush-current.html
N_Cook
news:pGLkp.1244$5t2....@newsfe06.ams2...
> 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
Phil Allison
"Nutcase fucking 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 bullshit.
Kook is such a retarded fuckwit, god know how he remembers to shit.
..... Phil
Mike Tomlinson
<grizzle...@comcast.net> 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
Mike Tomlinson
<sound....@btconnect.com> writes
>What's the antithesis of Occam's razor?
Occam's beard?
--
Mike Tomlinson
Mike Tomlinson
s.com>, Stroonz <str0...@aol.com> 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
Phil Allison
"Mike Tomlinson"
** What a BORING know nothing, fuckwit bullshit artist.
The LESS you know about a topic - the MORE you feel compelled to talk
bollocks about it.
I call that sort of rampant narcissism: " pommy disease ".
Wot a shame it ain't fatal.
.... Phil
William Sommerwerck
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 fucking look.
I especially love the way you squirm when backed into a corner.
William Sommerwerck
>> -- 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.
Phil Allison
"William Sommerwanker is a Lying Cunt "
>
> 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 fucking look !!!!!!!!!!!!!
You STINKING, AUTISTIC ARSEHOLE !!!
Phil Allison
"William Sommerwanker"
>
>>Some Bullshitting Pommy Fuckwit.
>
>>> 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 fucking RETARD !!!!!!!
.... Phil
Tim Schwartz
> 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.
>
> 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
Meat Plow
> What a BORING know nothing, fuckwit bullshit artist
Nice self-description.
--
Live Fast Die Young, Leave A Pretty Corpse
Dave Platt
>>> -- 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 <dpl...@radagast.org> 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!
Phil Allison
"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
Grant
>>>> 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.
Phil Allison
"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
N_Cook
20 deg C over with 0.4 amp mains with amp driving load.
Mike Tomlinson
writes
>This green thermistor limiter 10 deg C over ambient with no throughput and
>20 deg C over with 0.4 amp mains with amp driving load.
Bit warmer than I would be comfortable with.
--
Mike Tomlinson
Phil Allison
"Mike Tomlinson"
Nutcase Kook"
>
>>This green thermistor limiter 10 deg C over ambient with no throughput and
>>20 deg C over with 0.4 amp mains with amp driving load.
>
> Bit warmer than I would be comfortable with.
>
** So neither of you has a clue how NTC surge limiters are meant to work ?
..... Phil
N_Cook
news:GZ$5xNEjV...@jasper.org.uk...
Odd you say that. The next amp I looked at, this time mixer amp but also
300W and toroid Tx. Owner bought knowing 2 of the 8 channels were duff and
used as such for some years. He now needs all 8 ch .
Before he owned it , it must have been dropped and broke the awkward
size/shape mains switch. So someone spade jumpered the leads and covered
with heatshrink, leaving un-blanked off hole in chassis. Under his
heatshrink and touching the ordinary mains wire sleeving is an inrush
thermistor. Black , with 0.8mm leads, marked SG 130, 3.2R cold, 0.8R 20 sec
of soldering iron barrel. Presumably originally fixed to the sw and
unsupported other lead other than cable tie further down the cable loom.
Hopefully originally there was some woven glass sleeving over the thermistor
data for SG130 RTI Surge Guard, 0.07 ohms at 7 amps max , 2.5R at 25 deg C
27 joules rating for a 15 x 6.3 mm black (body radiator?) lump and .8mm
leads for anyone who can convert to temperature (not on the RTI datasheet)
N_Cook
http://www.rtie.com/ntc/surggard.htm
So for 7 amp NTC running outside of short duration peaks say an average 1/3
of 7 amps of mains 240V for driven amp and less than rated mains fuse then
125 degrees would be the operational maximum of the thermistor.
Would be nice to know a rule of thumb formula for real life "black body"
radiator/convector temperature and power consumption whether disc
thermistors or rod
resistors
N_Cook
over it and 102 deg C (ambient 18 deg C), no woven glass sleeve covering