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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.

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

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  • \$\begingroup\$ Oh! Thank you! Nice to have around, then... \$\endgroup\$ – xOneca Dec 20 '20 at 23:22
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    \$\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\$ – Sredni Vashtar Dec 21 '20 at 5:59
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    \$\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\$ – Unimportant Dec 21 '20 at 14:05
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    \$\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 '20 at 18:51
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    \$\begingroup\$ Notice how the connection is crimped rather than soldered, to avoid opening the fuse before it has even been used. \$\endgroup\$ – Andrew Morton Dec 21 '20 at 19:49

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