Main breaker tripping, dead CIM

[Ether]

Originally Posted by shagun.g

I've been trying to read up on this - I don't quite understand this concept. How you can use an op amp to measure the voltage drop (without a resistance)? How does this work?

There is resistance associated with the main breaker. So therefore there is a voltage drop across the main breaker associated with the current flowing through it.

The resistance of the main breaker is quite small, and thus the voltage drop across the breaker is quite small.

The op amp doesn't measure the voltage drop. It just amplifies it to a level suitable to be digitized by the A/D.

Instead of measuring the voltage drop across the main breaker, you could measure the voltage drop across a length of wire.