question re circuit breaker damage over continuous tripping

[slothybiggunz]

I am an audio tech and have been using a 15 amp thermal breaker on a 20 amp load (not my idea.) Needless to say, the breaker keeps tripping, shutting down one of my amplifiers.

In researching the damage issue to the breaker, I was told that every time it trips, the arcing that takes place leaves more and more damage to the contacts.

Could someone please confirm/deny this and explain what damage is being done.

Thank you.

 

[buzzp]

Yep, very true. Every time it breaks the load, arcing (severity depends on load) occurs. This arcing takes some of the metal off the contacts each time. Whats left is pitted contacts. These pitted contacts add resistance to the contact, increasing heating. As this repeats itself, the problem gets worse and worse, eventually the breaker will fail to make or worse yet, get very hot and fail potentially causing a fire.

 

[OperaHouse]

Just a comment. If you have breakers that get tripped all the time in test situations, you should consider using a PTTC device like PolySwitch RXE series. I'm using some 4A 50V versions and at rated current they have a voltage drop of about 0.2V. Since they are resistive you should not have any trouble paralleling them for higher current. They can take current bursts of twice the current for about 15 seconds. They do not totally interupt the power. Once tripped they consume about 3W to keep them hot. At 12V that is about 1/4 amp, 24V would be 1/8A, etc. Just remove voltage to reset in 10 seconds.