Closing bounce is an easily overlooked item in the mechanical characteristic test of high-voltage circuit breakers. Many people think that the "popping" of the contact is a normal phenomenon, and their focus is on the opening and closing time and speed. But the harm of excessive jumping is real and cumulative, and cannot be immediately seen.

How does bouncing occur

When the circuit breaker is closed, the moving contact moves towards the stationary contact at a certain speed. At the moment of contact between the two, due to the elasticity of the contact itself and the characteristics of the spring mechanism, the moving contact does not stop steadily as soon as it makes contact, but will briefly bounce and come back into contact - that is, "bounce". During the bouncing process, although the contact has macroscopically "closed", the contact is in a state of repeated opening and closing at the microscopic level.

The hazards of bouncing

During the bouncing period, although the gap between the contacts is extremely small (in millimeters), the interruption of the current will generate multiple arcs between the contacts. Each arc discharge will cause erosion of the contact surface, and over time, the contact surface of the contact will become rough and the contact resistance will increase; Severe bouncing may also lead to the evaporation of contact metal and a reduction in contact area, ultimately affecting normal current carrying and breaking capabilities.

What bounce parameters should HZC-4080 measure

The instruction manual lists the complete bouncing test content:

Closing bounce time of each fracture: the total time from the first contact of the contact to the final stable contact

Bounce frequency: How many times did the bounce occur

Bouncing process: Record the moment of each bounce and contact in full

Bounce waveform: a waveform diagram that visually displays the entire bouncing process

Opening rebound amplitude: the rebound distance after the moving contact moves during opening

These data are more comprehensive than just 'bounce time', and can distinguish whether the closing speed is too high (causing more bounce) or the contact spring stiffness is insufficient (causing longer bounce duration).

On the "Bounce Details" interface, HZC-4080 can display in detail the complete bouncing process of each fracture's first closing moment, first minute moment, second closing moment, etc. It is an important tool for finely analyzing the contact state.

The industry typically requires a closing bounce time of no more than 2ms for vacuum circuit breakers or 5ms for SF6 circuit breakers, subject to the manufacturer's specifications.