OP You should watch the voltage to see if it's getting low before the PI drops out. Generally measuring the voltage to determine the problem is iffy for you because the PI unit disconnects but if you see voltage under 108V it's at least a clue.
You are taking a risk by continuing to use power. Equipment is being cycled on and off which shouldn't be happening. More important if it is a neutral problem you could have very high and equipment killing voltage. It happened to me once and the PI unit protected the rig from 160V. It was a CG problem and I couldn't pull the rig plug fast enough.
Does your PI unit display voltage? What model do you have?
