Compressor Wiring

[akosin]

We were wiring our compressor to the robot today with the compressor leads to a spike and the pressure switch to the digital sidecar. When one of our mentors asked why I wasn't just wiring the compressor directly to the power board with the switch in series. We tried it and it worked great. Is this legal, or do I have to go back to the old wiring method?

Thanks,
Austin

[theawesome1730]

No, you must run the compressor through a Spike and use the Nason switch to tell your code to turn the compressor off.

[petet4]

First of all it is illegal to wire the switch like that and second the switch is not rated for the current the compressor will draw, it my work for awhile but will soon fail.

Here is the data for the switch


-pete

[akosin]

Ok

Thank You for your help!

[Richard Wallace]

Over the years I have learned many things from the FIRST team students I have mentored. The suggestion your mentor made about wiring the pressure switch directly to the compressor indicates a great opportunity for that mentor to learn from you now. The mentor's suggestion was well-intended, I believe, but was not based on a complete understanding of the rules and risks, as Pete explained above.

For reference, the pertinent rules are <R52> and <R87>. You should read them carefully before you explain to your mentor how the compressor and pressure switch wiring must be done.

I have inspected FRC robots at many events for several years. Many times I have seen the incorrect switch wiring that your mentor suggested, and have made the team correct it before their robot passed inspection. Once (thankfully only once!) I saw this kind of incorrect wiring result in a serious safety issue -- the switch, which as Pete pointed out is NOT rated for the electrical loading presented by a compressor, had failed due to arcing at its contacts, which fused them closed so that the compressor ran continuously -- until it overheated and smoke started to pour out. Luckily a heads-up field volunteer reached the robot's main breaker and stopped it before things got much worse.

[garyk]

... and I've seen mentors sticking compressor wires into the red Anderson battery connector(!!!). In a great demonstration of GP, FRC3256 (Valley Christian HS) loaned/scrounged the parts and helped the other team build a compliant pneumatic system in the pits at SVR.