High voltage/current Polyswitch-type device?

[Joel Kolstad]

[I tried this out on sci.electronics.components and didn't get a response, so
I figured I'd try here...]

Does anyone know of an auto-resetting fuse-like device that'll handle 120V @
5A or thereabouts? I've used Raychem PolySwitches in the past, but their
120/240V product offers (http://www.endrich.com/news/lvr_broschure.pdf) only
go up to 1.4A.

Thank you,
---Joel Kolstad

 

[Joerg]

Hello Joel,

Does anyone know of an auto-resetting fuse-like device that'll handle 120V @
5A or thereabouts? I've used Raychem PolySwitches in the past, but their
120/240V product offers (http://www.endrich.com/news/lvr_broschure.pdf) only
go up to 1.4A.

Give Weidmuller a call. They have (or at least used to have) breakers
that could somehow control themselves, signal that a trip had occurred
and be controlled remotely. Probably not cheap, but if they don't have
anything chances aren't that great that it exists elsewhere.

 

[Roy L. Fuchs]

Hello Joel,



Give Weidmuller a call. They have (or at least used to have) breakers
that could somehow control themselves, signal that a trip had occurred
and be controlled remotely. Probably not cheap, but if they don't have
anything chances aren't that great that it exists elsewhere.

A Polyswitch is a SMALL discreet device. I suspect that the
"breaker" you are suggesting weighs more than his entire design.

 

[Ken Smith]

[I tried this out on sci.electronics.components and didn't get a response, so
I figured I'd try here...]

Does anyone know of an auto-resetting fuse-like device that'll handle 120V @
5A or thereabouts? I've used Raychem PolySwitches in the past, but their
120/240V product offers (http://www.endrich.com/news/lvr_broschure.pdf) only
go up to 1.4A.

Read the plastic PTC datasheets carefully before you use them any any
serious voltage. The ones called "200V PTC" on the front of that data
sheet often are really limited to something like 60V in actual use.

If you can withstand the losses, a ceramic PTC may be better from your
application, if you can find one. They tend to have a higher untripped
resistance, and a softer knee but also a higher voltage rating.

 

[Joerg]

Hello Roy,

A Polyswitch is a SMALL discreet device. I suspect that the
"breaker" you are suggesting weighs more than his entire design.

Yes, they are about as large as a regular breaker. They actually have to
because they are mounted into the same kind of boxes. Just wanted to
mention these in case Joel finds himself between a rock and a hard spot,
where he can't find anything Polyswitch style at 5 amps but must offer
the protection. Could do it with a discrete circuit as well if it's for
a larger series.

 

[Joerg]

Hello Ken,

Read the plastic PTC datasheets carefully before you use them any any
serious voltage. The ones called "200V PTC" on the front of that data
sheet often are really limited to something like 60V in actual use.

Good point, I have seen some of these do the 4th of July thing.

If you can withstand the losses, a ceramic PTC may be better from your
application, if you can find one. They tend to have a higher untripped
resistance, and a softer knee but also a higher voltage rating.

I don't know if they are still made but in the early days of TVs the
sets contained power resistors that had a spring-loaded thermal release.
I considered them kind of dangerous because it was basically a spring
loaded solder joint, splattering off solder when they opened. But they
did work.

 

[Joel Kolstad]

Just wanted to mention these in case Joel finds himself between a rock and a
hard spot, where he can't find anything Polyswitch style at 5 amps but must
offer the protection.

Thanks for the idea, Joerg. It looks like we are just going to use fuses
(internally) and one of those combined IEC power entry/filtering/breaker
modules on the back of the chassis.

 

[Joerg]

Hello Joel,

Thanks for the idea, Joerg. It looks like we are just going to use fuses
(internally) and one of those combined IEC power entry/filtering/breaker
modules on the back of the chassis.

There are also very small breakers, about the size of a toggle switch
but 1.5 - 2 inches long. I forgot the brand I used but it was one of the
main European breaker mfgs, Schurter or something like that. Sometimes
you see these in ovens where an outlet must be limited to 15 amps while
the oven itself is hooked up to 30 or 40 amps. They come in various
sizes, IIRC I used one rated at 6 amps.

 

[ian field]

Hello Ken,


Good point, I have seen some of these do the 4th of July thing.



I don't know if they are still made but in the early days of TVs the sets
contained power resistors that had a spring-loaded thermal release. I
considered them kind of dangerous because it was basically a spring loaded
solder joint, splattering off solder when they opened. But they did work.

Years ago in the days of hybrid CTVs I remember one that had this type of
fusible resistor in the metal enclosure round the line O/P valve, there was
a warning label on the enclosure to use only low melting point cadmium
solder - and a little plastic clip holding a coiled up length of solder for
resetting the fusible resistor!

 

[Joerg]

Hello Ian,

Years ago in the days of hybrid CTVs I remember one that had this type of
fusible resistor in the metal enclosure round the line O/P valve, there was
a warning label on the enclosure to use only low melting point cadmium
solder - and a little plastic clip holding a coiled up length of solder for
resetting the fusible resistor!

Courtesy doesn't go that far anymore these days. When the thermo-fuse of
our hot water dispenser gave out I looked around everywhere in it, in
hopes of finding a spare. Nope. Had to drive 80 miles round trip for a
$1.15 part.

 

[Joel Kolstad]

Courtesy doesn't go that far anymore these days. When the thermo-fuse of our
hot water dispenser gave out I looked around everywhere in it, in hopes of
finding a spare. Nope. Had to drive 80 miles round trip for a $1.15 part.

I remember being very surprised as a kid the first time I found a device that
said, "User Serviceable Parts Inside" -- at first I thought I had mis-read it,
since up until that point I'd only ever seen the ubiquitous, "No user
serviceable parts inside!" -- The device in question was a tube radio from the
'60s that my mother had obtained in Germany as a student.

---Joel

 

[Joerg]

Hello Joel,

I remember being very surprised as a kid the first time I found a device that
said, "User Serviceable Parts Inside" -- at first I thought I had mis-read it,
since up until that point I'd only ever seen the ubiquitous, "No user
serviceable parts inside!" -- The device in question was a tube radio from the
'60s that my mother had obtained in Germany as a student.

I've got a few of those, some from Germany and one from Australia. The
ones from Germany would make the guys in the legal department of
"modern" companies cringe. Not that they weren't built well but their
manuals contained detailed instructions on how to rewire the transformer
to other line voltages, admonitions to switch to the correct fuse size,
and all all that happening right next to an electrolytic charged to a
good 300VDC.

Oh, and then I have one that runs sans transformer. All that would be
between you and possible electrocution is a rubber foot that falls out
or an antenna cap shorting out.

 

[Michael A. Terrell]

Courtesy doesn't go that far anymore these days. When the thermo-fuse of
our hot water dispenser gave out I looked around everywhere in it, in
hopes of finding a spare. Nope. Had to drive 80 miles round trip for a
$1.15 part.

I hope that you bought a spare while you were there.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Joerg]

Hello Michael,

I hope that you bought a spare while you were there.

Yes, Sir. I did.

And I even know where I put it

 

[Michael A. Terrell]

Hello Michael,


Yes, Sir. I did.

And I even know where I put it

Good man!


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Roy L. Fuchs]

Thanks for the idea, Joerg. It looks like we are just going to use fuses
(internally) and one of those combined IEC power entry/filtering/breaker
modules on the back of the chassis.

The use of Power Entry Modules are good practice for AC fed
products.

 

[legg]

[I tried this out on sci.electronics.components and didn't get a response, so
I figured I'd try here...]

Does anyone know of an auto-resetting fuse-like device that'll handle 120V @
5A or thereabouts? I've used Raychem PolySwitches in the past, but their
120/240V product offers (http://www.endrich.com/news/lvr_broschure.pdf) only
go up to 1.4A.

PTC devices can be operated safely in parallel to achieve higher
let-through currents.

Epcos offers a range of higher voltage PTCs, but 5A is a bit much for
any higher-voltage device.

http://www.epcos.com/web/generator/...mistors/Page,templateId=render,locale=en.html

RL

 

[Joel Kolstad]

PTC devices can be operated safely in parallel to achieve higher
let-through currents.

Thanks, I had thought of that and wasn't sure whether or not it was acceptable
to do so.

Epcos offers a range of higher voltage PTCs, but 5A is a bit much for
any higher-voltage device.

Perhaps 3 or 4 of the Raychem 1.4A ones would work well...