Pneumatic Fuse keeps blowing Team 3970

Starting after our recent regional at central valley we began to run into the issue of our fuse blowing. The fuse is connected to our pneumatics hub. Slot 21 and its a 20amp (mini automotive)

See this thread

tldr: Use a 20 amp breaker

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I would suggest switching to a breaker if you have the port. The team I’m on (2614) also had this issue, and after we switched to a 20 amp breaker we haven’t had an issue. This Thread Pneumatic Hub fuse blowing when robot browns out also covers this issue.

We blew a 20A this weekend…

We just went through this…Ended up having to replace the Rev Pneumatic Module. I actually caught this on video blowing the fuse while I was attached to the REV modules CAN BUS using the REV Hardware Client.

We bench tested the compressor that was attached to it with an amperage meter while it was running and hitting the pressure relief valve (at full pressure), and the Nason pressure switch with a meter and all that checked out ok. The Nason open and closed correctly when pressure was exhausted or filled up.

We replaced everything, new compressor, new Nason switch, new Rev Module, but also as suggested, moved the power for the REV Module from the 20 amp automotive fuse, to a 20 amp breaker spot on the PDB. So far it’s been holding up. But after two events, this is when ours started blowing fuses too randomly.

REV was nice enough to RMA our old board, they would like to check it out and see what’s up. They haven’t had a chance to provide much feedback, but I recommend testing your compressors and switch on the bench first. Make sure they working correctly, then replacing your module and moving to the resettable breaker.

My understanding of this problem is that it’s a current spike at compressor startup this drawing >20A and blowing the fuse, which is why the breaker works fine (spike is too short to actually trip it thermally). Your ammeter test may not have been fast enough to catch the spike (depending on the specific meter you used).

The REV PH has the ability to ramp power to the compressor to avoid this, but I don’t believe it currently does so. This is a software/firmware change they would need to make and it’s much too late in the season to be making changes like that.

This is almost certainly the case.

Compressor startup current when the system is unpressurized is low - compressor “startup” current when it’s starting up to recharge a partially depleted system is substantially higher and that current spiking about 20A is not unreasonable or concerning to me.

Breaker sounds like the way to go.

It’s really EASY to see if a “spike” or “dead-head” is happening with REV CLIENT software.

Just dump your air and enable your robot and watch the amperage climb using the REV CLIENT. See what the board is experiencing.

You should see something like this. In this video, we caught the fuse blowing at the top end of pressure, but the switch was not made, nor did it get to the point it would start relieving pressure with the saftey blow off valve. We thought we had a bad compressor, until we bench tested it ok, but just to be safe, we installed a new compressor anyway.

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Was the roboRIO or rev client in control in that video? If the former, what is your CAN utilization? The interesting thing is that turns off and then turns back on at pressure, which is likely what caused it to blow. The question is what caused it to turn off momentarily.

The current draw on the Viar90 compressors has ranged wildly. As others have stated, putting this on a 20A channel with a resetting breaker is the fool proof way to make sure you don’t have an issue. We have a few things on the Firmware side that we are working on that should remediate this issue for future seasons, but for now the 20A resetting breaker is our recommendation.


We frequently get a “double tap” finish when arriving at high pressure with the viair 90c, standard sensor, 9 tanks, and rev pneumatics hub.

I assume something like crossing over the physical trigger point of the sensor, cutting power to the compressor, and losing a half cycle somewhere that bumps us back below the sensor reading? Then it cuts back on for another second, then off.

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