fusesidentification
Found this fuse at work. Normally these fuses have a single wire inside but this one has a little black "resistor"-looking thing on a spring. What is up?
First picture is of a "normal" fuse. The second one is the fuse i found at work. Hard to take pictures sorry.
Finding a fuse with those characteristics is going to be difficult. I'd use a current shunt with a suitable MCU and circuit breaker and monitor the current taken by the device, shutting off the current if it rises above 120A for 15 seconds.
Two fuses in parallel can cause problems unless they are well-matched and the holders are properly designed. Any difference between them can cause one fuse to take more current than the other one, and fail.
It is a thermostat as Dave Tweed and Kaz noticed.
I got a similar one and it has the temerature written on it:
Best Answer
It's a "slow-blow" fuse designed to take a short high current impulse without opening, but to open for a long term overload or a brief very high current (such as a short circuit). Quite common.
As always, replace with the same type and rating for continued protection (and no nuisance blowing).
Edit:
The spring puts the element under tension which allows them more degrees of freedom to adjust the characteristics. I believe the black thing is a resistive element. See more info in US2386094.