What's this surge protection component?

D

DaveC

Guest
http://home.covad.net/~peninsula/Amp/Surge1.jpg

This is in an audio power amp, in *series* with the fuse and the mains power
switch. I've seen protection devices in parallel with the mains, and chokes
in series, but I can't remember seeing a device such as this in series.

What is it? Is it (in it's former, non-crisp state) appropriate in this
application? Replace with something newer/better? Remove altogether?

Thanks,
--
DaveC
me@privacy.net
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"DaveC" <me@privacy.net> wrote:
http://home.covad.net/~peninsula/Amp/Surge1.jpg
What is it? Is it (in it's former, non-crisp state) appropriate in this
application? Replace with something newer/better? Remove altogether?
Click to expand...
It is an "inrush limiter", don't know the correct english word for it,
in German it's called a "NTC", a resistor wihich will go down in its
value when heated by the current flowing through it. So it has a high
resistance at startup, effectivly limiting the charging current for the
smoothing capacitors and transformer to something which wouldn't burn the
fuse, and when heated up it is almost a short to provide sufficient current
for the amplifier to operate.

If You have a slow fuse, try shorting it, if the fuse blows, You have to
get a replacement for the NTC.

just my 2 cent, Michael.

P.S.Sorry for my bad English, i'm not a native speaker...
 
On Fri, 14 Nov 2003 10:43:17 +0100, "Michael Buchholz" <cylly@wtal.de>
wrote:

"DaveC" <me@privacy.net> wrote:
http://home.covad.net/~peninsula/Amp/Surge1.jpg
What is it? Is it (in it's former, non-crisp state) appropriate in this
application? Replace with something newer/better? Remove altogether?

It is an "inrush limiter", don't know the correct english word for it,
in German it's called a "NTC", a resistor wihich will go down in its
value when heated by the current flowing through it. So it has a high
resistance at startup, effectivly limiting the charging current for the
smoothing capacitors and transformer to something which wouldn't burn the
fuse, and when heated up it is almost a short to provide sufficient current
for the amplifier to operate.

If You have a slow fuse, try shorting it, if the fuse blows, You have to
get a replacement for the NTC.

just my 2 cent, Michael.

P.S.Sorry for my bad English, i'm not a native speaker...



Michael, your English is better than that of 95% of native speakers.
Click to expand...
Useful post as well.

d

_____________________________

http://www.pearce.uk.com
 
"Michael Buchholz" <cylly@wtal.de> schrieb:

just my 2 cent, Michael.

P.S.Sorry for my bad English, i'm not a native speaker...
Click to expand...
Sorry for Crosspost, Clicked 'send' and didn'd see the
Groups...

F'up to sci.electronics.components

Michael.
 
On Fri, 14 Nov 2003 1:43:17 -0800, Michael Buchholz wrote
(in message <bp2831$d97$00$1@news.t-online.com>):

It is an "inrush limiter", don't know the correct english word for it,
in German it's called a "NTC", a resistor wihich will go down in its
value when heated by the current flowing through it. So it has a high
resistance at startup, effectivly limiting the charging current for the
smoothing capacitors and transformer to something which wouldn't burn the
fuse, and when heated up it is almost a short to provide sufficient current
for the amplifier to operate.

If You have a slow fuse, try shorting it, if the fuse blows, You have to
get a replacement for the NTC.
Click to expand...
Thanks, Michael, for your reply. Very helpful.

Can someone please give me the English name for this, and maybe an on-line
reference to a manufacturer or supplier?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group
 
I read in sci.electronics.design that Michael Buchholz <cylly@wtal.de>
wrote (in <bp2831$d97$00$1@news.t-online.com>) about 'What's this surge
protection component?', on Fri, 14 Nov 2003:

It is an "inrush limiter", don't know the correct english word for it,
Click to expand...
'Inrush limiter' is OK.

in German it's called a "NTC", a resistor wihich will go down in its
value when heated by the current flowing through it.
Click to expand...
Properly, 'NTC thermistor' NTC = Negative Temperature Coefficient (of
resistance).
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
 
Michael Buchholz wrote:

"DaveC" <me@privacy.net> wrote:
http://home.covad.net/~peninsula/Amp/Surge1.jpg
What is it? Is it (in it's former, non-crisp state) appropriate in this
application? Replace with something newer/better? Remove altogether?

It is an "inrush limiter", don't know the correct english word for it,
in German it's called a "NTC", a resistor wihich will go down in its
value when heated by the current flowing through it. So it has a high
resistance at startup, effectivly limiting the charging current for the
smoothing capacitors and transformer to something which wouldn't burn the
fuse, and when heated up it is almost a short to provide sufficient current
for the amplifier to operate.

If You have a slow fuse, try shorting it, if the fuse blows, You have to
get a replacement for the NTC.

just my 2 cent, Michael.

P.S.Sorry for my bad English, i'm not a native speaker...
Click to expand...
Your English is *far* better than many of the 'native' posters seen here.
fp
 
On Fri, 14 Nov 2003 6:32:07 -0800, John Woodgate wrote
(in message <MsxWtfBndOt$Ewu6@jmwa.demon.co.uk>):

Properly, 'NTC thermistor' NTC = Negative Temperature Coefficient (of
resistance).
Click to expand...
Thanks, John.

Jameco has a list of NTC Varistors:

http://www.jameco.com/Jameco/Products/ProdCT/p091.pdf

These seem like they're transducers for measuring temperature. The specs list
max dissipation as 0.55W. Seems a little lightweight for an inrush limiter. I
think that they are, in this circuit, being required to dissipate much more
than that.

Is this component really appropriate in this application? With the inrush
current this amp has, I just have a hard time seeing any of these components
handling the current.

Is there a better component? A simple resistor, maybe?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group
 
Found this application data from a manufacturer:

http://www.ametherm.com/Inrush_Surge_Limiters.htm

and

http://www.ametherm.com/Transformer_case_study.htm

Seems that Jameco carries some of the lightweight models... The above
references show specs up to 36 A.

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group
 
Michael Buchholz wrote:

"DaveC" <me@privacy.net> wrote:
http://home.covad.net/~peninsula/Amp/Surge1.jpg
What is it? Is it (in it's former, non-crisp state) appropriate in
this application? Replace with something newer/better? Remove
altogether?

It is an "inrush limiter", don't know the correct english word for it,
in German it's called a "NTC", a resistor wihich will go down in its
value when heated by the current flowing through it. So it has a high
resistance at startup, effectivly limiting the charging current for
the smoothing capacitors and transformer to something which wouldn't
burn the fuse, and when heated up it is almost a short to provide
sufficient current for the amplifier to operate.

If You have a slow fuse, try shorting it, if the fuse blows, You have
to get a replacement for the NTC.

just my 2 cent, Michael.

P.S.Sorry for my bad English, i'm not a native speaker...
Click to expand...
are you talking about a resetable fuse?
Raychem is one manufacturer followed by many others.
rw
 
"Rein Wiehler" <rwiehler@netscape.net> schrieb:
If You have a slow fuse, try shorting it, if the fuse blows, You
have
to get a replacement for the NTC.

are you talking about a resetable fuse?
Raychem is one manufacturer followed by many others.
Click to expand...
No, I meant replacing the NTC thermistor by a piece of wire , but this
only
works if the OP has a slow fuse in the Utility panel, otherwise this
fuse will blow due the inrush current not longer being limited.

Michael.
 
On Fri, 14 Nov 2003 7:04:14 -0800, the renowned DaveC <me@privacy.net>
wrote:

Found this application data from a manufacturer:

http://www.ametherm.com/Inrush_Surge_Limiters.htm

and

http://www.ametherm.com/Transformer_case_study.htm

Seems that Jameco carries some of the lightweight models... The above
references show specs up to 36 A.
Click to expand...
Check also the Thermometrics line. Note that they don't really limit
if you don't allow them to cool down, so a short blip in the line
voltage can result in a much larger than normal inrush current surge.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
"DaveC" <me@privacy.net> wrote in message
news:0001HW.BBDA213500480FE1F0305600@news.individual.net...
On Fri, 14 Nov 2003 1:43:17 -0800, Michael Buchholz wrote
(in message <bp2831$d97$00$1@news.t-online.com>):

It is an "inrush limiter", don't know the correct english word for it,
in German it's called a "NTC", a resistor wihich will go down in its
value when heated by the current flowing through it. So it has a high
resistance at startup, effectivly limiting the charging current for the
smoothing capacitors and transformer to something which wouldn't burn
the
fuse, and when heated up it is almost a short to provide sufficient
current
for the amplifier to operate.

If You have a slow fuse, try shorting it, if the fuse blows, You have to
get a replacement for the NTC.

Thanks, Michael, for your reply. Very helpful.

Can someone please give me the English name for this, and maybe an on-line
reference to a manufacturer or supplier?
Click to expand...
It is a NTC - Negative Temperature Coeffiecent resistor. www.digikey.com
sells them. Also note there are many sizes - you have to match them to the
current drawn through it.

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group
Click to expand...
 
It is an "inrush limiter", don't know the correct english word for it,
in German it's called a "NTC", a resistor wihich will go down in its
Click to expand...
In English it's called an NTC, because that's an acronym for Negative
Temperature[Thermal] Coefficient [resistor].
 
"DaveC" <me@privacy.net> wrote in message
news:0001HW.BBDA213500480FE1F0305600@news.individual.net...
On Fri, 14 Nov 2003 1:43:17 -0800, Michael Buchholz wrote
(in message <bp2831$d97$00$1@news.t-online.com>):

It is an "inrush limiter", don't know the correct english word for it,
in German it's called a "NTC", a resistor wihich will go down in its
value when heated by the current flowing through it. So it has a high
resistance at startup, effectivly limiting the charging current for the
smoothing capacitors and transformer to something which wouldn't burn
the
fuse, and when heated up it is almost a short to provide sufficient
current
for the amplifier to operate.

If You have a slow fuse, try shorting it, if the fuse blows, You have to
get a replacement for the NTC.

Thanks, Michael, for your reply. Very helpful.

Can someone please give me the English name for this, and maybe an on-line
reference to a manufacturer or supplier?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

The KCC marking is for Keystone Carbon Company, now apparently part of
Click to expand...
Thermometrics. Here's the NTC page -
http://www.thermometrics.com/htmldocs/numindex.htm
Digikey distributes them - http://dkc3.digikey.com/pdf/T033/0821-0822.pdf

Regards,
Ralph in NH
 
I read in sci.electronics.design that DaveC <me@privacy.net> wrote (in
<0001HW.BBDA2D8E004AF4C1F0305600@news.individual.net>) about 'What's
this surge protection component?', on Fri, 14 Nov 2003:

Is this component really appropriate in this application? With the
inrush current this amp has, I just have a hard time seeing any of these
components handling the current.
Click to expand...
Just as there are resistors (1/10 W) and resistors (100W), there are
different types of NTC, with vastly different current and power ratings.
Is there a better component? A simple resistor, maybe?
Click to expand...
No. A resistor would permanently cut down the supply voltage to the
transformer AND heat up the product.

Other posts have pointed you to more appropriate types of NTC.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!
 
DaveC wrote:
On Fri, 14 Nov 2003 6:32:07 -0800, John Woodgate wrote
(in message <MsxWtfBndOt$Ewu6@jmwa.demon.co.uk>):

Properly, 'NTC thermistor' NTC = Negative Temperature Coefficient (of
resistance).

Thanks, John.

Jameco has a list of NTC Varistors:

http://www.jameco.com/Jameco/Products/ProdCT/p091.pdf

These seem like they're transducers for measuring temperature. The specs list
max dissipation as 0.55W. Seems a little lightweight for an inrush limiter. I
think that they are, in this circuit, being required to dissipate much more
than that.

Is this component really appropriate in this application? With the inrush
current this amp has, I just have a hard time seeing any of these components
handling the current.

Is there a better component? A simple resistor, maybe?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group
Click to expand...
Dave,

For some good information on these devices:
http://www.thermometrics.com/assets/images/cl.pdf

Both Mouser & Digikey have them.
For Mouser:
http://www.mouser.com/
then enter current limiter in the parts search box.

For Digikey:
http://dkc3.digikey.com/PDF/T033/0821.pdf

Scroll down about 3/4 of the page - you'll see
Inrush Current Limiters. They have a wide range of values -
you'll find one suitable for your amplifier. In the absence
of any other information, select one near, (but not lower
than) the value of the fuse in your amp.

A resistor is not a suitable replacement for one of these
limiters. Also, while using a jumper, as was mentioned in
another reply, can be a good diagnostic effort, I would
recommend against leaving it in as a permanent solution.
 
On Fri, 14 Nov 2003 13:03:15 -0800, ehsjr@bellatlantic.net wrote
(in message <3FB542F8.D10AEAD0@bellatlantic.net>):

A resistor is not a suitable replacement for one of these
limiters. Also, while using a jumper, as was mentioned in
another reply, can be a good diagnostic effort, I would
recommend against leaving it in as a permanent solution.
Click to expand...
Why is it not a good idea to leave it jumpered rather than replacing it with
another NTC varistor? I know the inrush current will be high, and possibly
blow the slow-blow fuse, but if I notch that up another amp or so, what's the
down side? Is this too much current for the rectifier, transformer windings,
etc., in the PS circuit?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group
 
"DaveC" <me@privacy.net> wrote in message
news:0001HW.BBDACAC8006FCE84F0305600@news.individual.net...
On Fri, 14 Nov 2003 13:03:15 -0800, ehsjr@bellatlantic.net wrote
(in message <3FB542F8.D10AEAD0@bellatlantic.net>):

A resistor is not a suitable replacement for one of these
limiters. Also, while using a jumper, as was mentioned in
another reply, can be a good diagnostic effort, I would
recommend against leaving it in as a permanent solution.

Why is it not a good idea to leave it jumpered rather than replacing it
with
another NTC varistor? I know the inrush current will be high, and possibly
blow the slow-blow fuse, but if I notch that up another amp or so, what's
the
down side? Is this too much current for the rectifier, transformer
windings,
etc., in the PS circuit?
Click to expand...
Yes, and to even suggest going to a higher amperage fuse to hack around this
makes me wonder if you should be poking around inside it in the first place.
Is it cheaper to burn down your house than to spend $2.50 on the right part?
 
On Fri, 14 Nov 2003 18:25:16 -0800, James Sweet wrote
(in message <g8gtb.3446$Dw6.27604@attbi_s02>):

Yes, and to even suggest going to a higher amperage fuse to hack around this
makes me wonder if you should be poking around inside it in the first place.
Is it cheaper to burn down your house than to spend $2.50 on the right part?
Click to expand...
Oh, let's not get too dramatic, here, please.

Increasing the fuse might be dangerous, but it's gonna cause whatever damage
while I'm standing right there when turn it on, not hours later.

Please don't dramatize and use fear-based logic just to make a point. People
burn down houses using extension cords for electric heaters, not by
increasing the fuse on an audio amplifier while testing it or repairing it.

But *PLEASE* let's not continue this new thread (ie, safety, etc.) here. I
want to not dilute the discussion about the NTC varistor and alternatives.

If you want to continue a discussion of whether or not you think I'm sane or
qualified to work on my own amp, start another thread or contact me off-line:
dave-univ3660ATcovadDOTnet

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group
 
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