Patent ID: 9551752
Date: 2017-01-24
CPC Classifications: G01R

Claim:
1. A system for testing substation circuit breakers while the circuit breakers are grounded on both sides, the system comprising: a) a substation circuit breaker grounded on both sides of the circuit breaker contacts; b) a ground clamp probe electrically connectable to one side of the circuit breaker contacts, where the ground clamp probe provides a means of interfacing standard test equipment to the circuit breaker without removing either safety ground; and c) a microcontroller communicatively coupled to the ground clamp probe comprising instructions for analyzing the circuit breaker, where the microcontroller comprises instructions to: a) calculate the impedance of a ground loop; b) operate the ground clamp probe, an H-bridge and a solid state switch; c) control the H-bridge to switch DC input voltage from a power module to form a bi-directional pulsed waveform drive; d) control drive coil voltage and current; e) drive the H-bridge at a frequency f and a programmable duty cycle, where the frequency, f, is chosen to be high enough to accurately time the breaker, but low enough that loop current is not severely limited by loop inductance L; and the duty cycle can be adjusted to give the desired drive current into a standard load; f) process output signals of analog-to-digital converters, a first analog-to-digital converter for current, and a second analog-to-digital converter for voltage; g) calculate if the substation circuit breaker is open or closed based on sensed current and voltage; h) control the solid state switch: and i) to adapt sense thresholds to more accurately measure the circuit breaker.