hello all,
I have just found out the supply to the commutator is not 400V/300A but about 10V/300A. Can a general purpose op amp can easily handle these values? will I still need an isolation amplifire? If I am using an op-amp as a differece amp just to measure the volt drop across 2 commutator bars, can I just place its inputs on the bars? the way I see it, the test supply to the commutator is a different loop from my control cct, hence what will the op amp use as a reference point.

Put clearly, if there are 2 seporate grounds present, and the control cct ground is different from the test supply ground, will I get an accurate voltage difference across two bars is I simply place the op amp inputs on the bars? I was using the analogy of a digital multimeter, where the ground of the cctry in the digital multimeter is different from that of the cct on which measurements are to be made, yet an accurate volt drop can still be measured. will my op amp and measuring cctry work in the same way?

Thank you for your time.
sun