During substation circuit breaker maintenance, why do the opening and closing times of switches on the same feeder never match? The problem is often not with the circuit breaker itself, but with the test wiring and sensor installation.
The tester connects to the circuit breaker auxiliary contacts and linear/angular displacement sensors through the time channel and travel channel respectively. The control wires for the closing coil and opening coil should be taken directly from the operating mechanism terminals, avoiding shared nodes with the protection circuit. The unit provides an internal DC220V operating power supply, and external AC or DC voltage can also be connected according to site conditions. Before wiring, confirm that the coil rated voltage matches the tester output setting.
The linear sensor should be parallel to the direction of movement of the moving contact rod, and the angular displacement sensor should be connected to the main shaft via a linkage. After installation, perform one manual opening and closing operation to observe whether the travel curve is continuous without jumps. The sensor range should preferably cover more than 1.2 times the total travel of the circuit breaker, and the mounting bracket should have sufficient rigidity to reduce vibration interference at the moment of opening and closing.
The tester uses a high-speed data acquisition system to record opening/closing time, simultaneity, bounce count and bounce time, travel, and speed characteristics. Technical engineers can use this to judge the working status of the operating mechanism and arc extinguishing chamber. It is recommended to compare the measurement results with the circuit breaker factory test data to form a longitudinal trend record.
Keep the storage environment dry and ventilated, with a temperature of -10℃ to 50℃ and humidity not exceeding 85%RH. During long-distance transportation, the sensors and test leads should be packed separately to avoid extrusion causing zero drift of the displacement elements.
