What component is this? They have a temperature printed, and a part code, but both are pretty much erased in the purple part. The orange one is a bit more readable, but not much. I think they may be resistors, but I'm not sure.

Unknown components

This is the information I can read from both parts:

  • Orange: T1 = 169 °C; D167PHMP
  • Purple: 184 °C

The measured resistance on both seems to be about 3-5 Ω.


1 Answer 1


Those are thermal fuses. They break the connection permanently once a certain temperature is reached to protect devices from overheating and possibly causing fire.

  • \$\begingroup\$ Oh! Thank you! Nice to have around, then... \$\endgroup\$
    – xOneca
    Dec 20, 2020 at 23:22
  • 4
    \$\begingroup\$ Is there a general reason for the U bend? Like thermal expansion or something like that or it just happen to be this way for unknown circuit specific reasons (geometric constraint...) \$\endgroup\$ Dec 21, 2020 at 5:59
  • 2
    \$\begingroup\$ @SredniVashtar They don't come like that when new so most likely it's application specific, being shaped like that to fit inside some kind of retention in the device. \$\endgroup\$ Dec 21, 2020 at 14:05
  • 2
    \$\begingroup\$ Maybe the thermal fuse had to be touching a certain part of the device (like in an electrical heating plate, they sometime touche the plates), to make them as useful as possible. \$\endgroup\$
    – lalala
    Dec 21, 2020 at 18:51
  • 3
    \$\begingroup\$ Notice how the connection is crimped rather than soldered, to avoid opening the fuse before it has even been used. \$\endgroup\$ Dec 21, 2020 at 19:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.