[time-nuts] 10811 Thermal fuse?

[Mike Feher]

This type of cutout fuse can never re-connect. It is a very clever design where there are two metal strips in contact with each other that have springiness to them, so, they would normally not be in contact. During assembly, the fuse cavity is filled with a waxy material, consistency dependent on temperature cut-out requirements. As the critical temperature is reached, the wax melts, and, the two springy steel contacts separate. Of course then the unit cools down, the wax hardens, and the contacts stay separated. As I said in a previous post, these fuses tend to age and eventually open up even in a well performing circuit. Regards - Mike 

Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of Dave Daniel
Sent: Tuesday, September 02, 2014 8:05 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 10811 Thermal fuse?

I believe a thermal cut-out is a device which interrupts the circuit when a prescribed temperature is reached or exceeded (in some cases by heating from an increase in current through a conductor), but which re-connects the circuit once the temperature has dropped below the cut-out temperature (possibly with some hysteresis built in). A fuse, on the other hand, interrupts the circuit after a certain current threshold is exceeded (and, of course there is an increase in temperature related to the increase in current) but which is destroyed in the process out interrupting the circuit.

DaveD