Leon Zhang

A current clamp meter measures live current without breaking the circuit; this selection guide covers types, key specifications, true RMS and safe test setup.

Hi pot testing stresses insulation out of service with an overvoltage and watches the leakage; this guide covers voltage selection, AC/DC/VLF choice and setup.

How to test a circuit breaker step by step: prove dead, measure contacts and insulation, and prove the protection operates the breaker.

How to choose a ground resistance tester by method, probe spacing and interference, and how to read soil resistivity and touch voltage limits.

How to choose a power quality analyzer by class, channels and recording setup, and how to read harmonics, unbalance and events on a real supply.

How to choose a megohmmeter by test voltage and range, read the number after temperature correction, and set up insulation tests for motors and chillers.

How a voltage transformer behaves under real burden, how IEC and IEEE accuracy notations differ, and the field tests that catch a defective unit before service.