jeff_wisnia wrote:

N_Cook wrote:

jeff_wisnia wrote in message
...

Over the years I've had a few thermal fuses in houshold appliances go
open for no apparent reason. When I've replaced them with ones with the
same temperature rating they stayed working fine for years more.

A couple of days ago our three year old Bunn coffee maker quit, because
a 141 degree celcius overtemperature thermal fuse on the water tank
opened. It might possibly have happened because the water tank
thermostat stuck closed, but after I repaired it the thermostat cycled
just as it should.

I was suprised to find that there were TWO identical thermal fuses
connected in series located right next to each other, the bodies were
actually touching. That seemed like a belt and suspenders approach,
unless there's a significant likelihood that a thermal fuse won't open
when it should?

Comments?

Thanks guys,

Jeff


--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.



The larger resettable switch type are usually rated as combined
(self-heating) current and thermal cutout. Maybe similar for "Woods" metal
types , say if in circuit with fast switching on and off thermostat or poor
contacts , so repeated inrush curent combined with a standing temperature.



The thermal fuse in our Bunn coffeemaker was marked as being made by
MicroTemp, labled series G7.

Just for Ss & Gs I looked them up today and learned that there's more
inside them than just a "fuse link" that melts at the trip temperature.

There's quite a bit of stuff in that little sucker.

Look he

http://tinyurl.com/786eslm

Works just like the little plastic things that come in Thanksgiving
turkeys.

Cheers

Phil Hobbs