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Diode or what?

Started by ralph day, January 23, 2020, 08:26:44 AM

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ralph day

Hi all
I pulled this out of a non functioning dump load oil/radiant 700watt heater.  I'm assuming it's a diode of some kind.  It was between 2 of the safeties, one detecting heat, the other detecting tip over.  Info on it as follows:


Cd  E  (But the E is the mathematical sign for something, epsilon?)
Tf 128deg C
D125 SNEU
Light blue band around the bottom.


Am I right that it's a diode?

Thanks
Ralph


Vic

Hi Ralph,

Would bet that this is a "Thermal Fuse",   designed to protect against over-temperature conditions,  if the thermostatic control fails in the ON condition.

FWIW,   Vic
Off Grid - Sys 1: 2ea SW+ 5548, Surrette 4KS25 1280 AH, 5.25 KW PV, Classic 150,WB, Beta Barcelona, Beta KID
Sys 2: SW+ 5548s, 4KS25s, 5.88 KW PV, 2 ea. Classic 150, WB, HB CC-needs remote Monitoring/Control, site=remote.
 MN Bkrs/Bxs/Combiners. Thanks MN for Great Products/Svc/Support&This Forum!!

ralph day

Thanks Vic.  That's just what my EE friend said after I posted.  Now to source one.

Ralph

mike90045

http://tinyurl.com/LMR-Solar

Classic 200| 2Kw PV, 160Voc | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph )| Listeroid 6/1, st5 gen head | XW6048 inverter/chgr | midnight ePanel & 4 SPDs | 48V, 800A NiFe battery bank | MS-TS-MPPT60 w/3Kw PV

ralph day

Replacement on order from a reasonably local company.  3 times cost of unit for shipping.  It would fit in an envelope.

Son inlaw commented that if it failed once was that a safety reason it failed?  Hmm.  Bench test before putting into service, but it's good to know the fuse failed (if it was heat related).

Ralph

ClassicCrazy

I think a lot of consumer items get thrown away when those thermal fuses open up. I have replaced some in various things that I salvaged here and there.  You can usually find thermal fuses on ebay for not too much .

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

ralph day

Does a thermal fuse blow when the temperature around it reaches the critical point (in this case 128deg C), or does the current passing through it cause the fuse to blow (from over current for too long?).  Isn't that just like a regular fuse or breaker, but permanently wired in?

Never having heard of thermal fuses of this type leaves me in the dark.

Ralph

ClassicCrazy

Quote from: ralph day on January 26, 2020, 08:04:41 AM
Does a thermal fuse blow when the temperature around it reaches the critical point (in this case 128deg C), or does the current passing through it cause the fuse to blow (from over current for too long?).  Isn't that just like a regular fuse or breaker, but permanently wired in?

Never having heard of thermal fuses of this type leaves me in the dark.

Ralph
The heat opens them up .
This guy took one apart and explained how it worked.
https://youtu.be/bfTSa1skOHY

Larry
system 1
Classic 150 , 5s3p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system 2
 5s 135w Kyocero , 3s3p 270w Kyocera  to Classic 150 ,   8s Kyocera 225w to Hawkes Bay Jakiper 48v 15kwh LiFePO4 , Outback VFX 3648 inverter
system 3
KID / Brat portable

boB

I like self resetting PTCs if the voltage and current rating are correct.

K7IQ 🌛  He/She/Me

ralph day

Never having heard of thermal fuses before last January I've had another visit with them.  My daughter's first Instant Pot (pressure cooker) died.  Again, it was the thermal fuse.  $1.50 part, $3.00 shipping and we're back in business.

So anything that has heat, like a heater, Instant Pot, rice cooker etc will have one of these things.  The selection is crazy.  For 10 amp, 250volt there were dozens of various temperature ratings.  The extra for last year's oil heater fix was 20deg C too low for the cooker, so not usable.  My electronics stash now has 2 variants of thermal fuses, usable only in their purchased for use likely.

RAlph

boB

Quote from: ralph day on April 09, 2021, 07:54:49 AM
Never having heard of thermal fuses before last January I've had another visit with them.  My daughter's first Instant Pot (pressure cooker) died.  Again, it was the thermal fuse.  $1.50 part, $3.00 shipping and we're back in business.

So anything that has heat, like a heater, Instant Pot, rice cooker etc will have one of these things.  The selection is crazy.  For 10 amp, 250volt there were dozens of various temperature ratings.  The extra for last year's oil heater fix was 20deg C too low for the cooker, so not usable.  My electronics stash now has 2 variants of thermal fuses, usable only in their purchased for use likely.

RAlph


I bet UL or ETL or whoever the NRTL was made them put that part in there to make it safe. 

The more parts there are, the more trouble you can have I suppose.


K7IQ 🌛  He/She/Me