Author Topic: Diode or what?  (Read 311 times)

ralph day

  • Jr. Member
  • **
  • Posts: 97
Diode or what?
« on: January 23, 2020, 08:26:44 AM »
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

  • Hero Member
  • *****
  • Posts: 2196
Re: Diode or what?
« Reply #1 on: January 23, 2020, 11:07:26 AM »
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 - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

ralph day

  • Jr. Member
  • **
  • Posts: 97
Re: Diode or what?
« Reply #2 on: January 23, 2020, 12:57:57 PM »
Thanks Vic.  That's just what my EE friend said after I posted.  Now to source one.

Ralph

mike90045

  • Hero Member
  • *****
  • Posts: 755
    • The Ranch (via facebook re-direct)
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

  • Jr. Member
  • **
  • Posts: 97
Re: Diode or what?
« Reply #4 on: January 24, 2020, 07:43:41 AM »
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

  • Hero Member
  • *****
  • Posts: 2317
Re: Diode or what?
« Reply #5 on: January 24, 2020, 09:50:47 PM »
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 one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

ralph day

  • Jr. Member
  • **
  • Posts: 97
Re: Diode or what?
« Reply #6 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

ClassicCrazy

  • Hero Member
  • *****
  • Posts: 2317
Re: Diode or what?
« Reply #7 on: January 26, 2020, 11:41:25 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 one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

boB

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3119
Re: Diode or what?
« Reply #8 on: January 26, 2020, 09:21:43 PM »
I like self resetting PTCs if the voltage and current rating are correct.

K7IQ