Compressor Blowing Spike 20A Fuse

Our compressor was running fine earlier today, then we bypassed the automatic shutoff to test the relief valve, and our spike 20A fuse blew. We then took a different fuse, put it in, and then that fuse blew around when it should have shut off at 120psi (no bypassing this time). Is anyone else having a similar problem?

Check the rules to be sure they haven’t changed. In the past it was possible to use a breaker that resets; same as the motors.

Not sure that answers the question about why you are blowing fuses, but if you plan on using air cylinders and have the compressor on board, you will want to use a breaker instead of a fuse.

*<R55> E. A fuse on a relay feeding the compressor may be replaced with a 20 Amp Snap-Action circuit breaker.

This is a must. The compressor will require a snap-action breaker on the spike.

So for the compressor spike relay, the fuse that came with the relay has to be replaced with a 20 Amp Snap-Action circuit breaker?

It is not required by the rules, but if you don’t do it blowing the fuse is not a matter of if but when.

It is not required to be replaced.

However, any veteran team who didn’t make the substitution at some point will tell you that having your compressor stop working mid-match is almost the worst thing in the competition, second only to losing your main battery mid-match and/or losing communication with the driver’s station mid-match.

Replacing the fuse with a breaker is what could be termed, “very highly recommended practice”. Not quite required, but odds are everybody’s done it already.

Yeah, we learned to do this last year with our pneumatic suspension system. Blew out 3 fuses before looking in the manual and putting in a Snap-Action breaker instead, and didn’t had a problem since then.

If the compressor starts up when the system is almost at pressure the inital surge is higher than the standard fuse rating. Then it’s just a game of chance as to whether the fuse blows. I think the resettable fuses have a longer time constant and can get past the startup surge.

While the compressor run current is in the 10-12 amp range for the old style compressor, the start current is in the 25-27 amp range. You will blow the 20 amp fuse, guaranteed. The Viair compressor does not have the same specs and only states max current is 10 amps. I am going to guess that start current is higher.
An inspector would suggest you change that fuse to a breaker. Please take that advice.