Installation Tips for Vacuum Circuit Breaker Pole Units

The solidified pole unit is a core component of vacuum circuit breakers, its installation quality directly affects loop resistance, phase imbalance, and the service life of the arc extinguishing chamber bellows. Many issues such as overheating, bouncing, and jamming originate from assembly details. Here are practical installation tips based on field experience:

a. Tighten the pole unit fixing bolts diagonally in 2–3 stages using a torque wrench.

b. Ensure the pull rod and dynamic conductive rod of the pole unit remain concentric. Any tilt or misalignment will generate lateral forces during opening and closing, continuously stressing the bellows of the arc extinguishing chamber. Over time, this may lead to bellows damage and vacuum leakage. After initially securing the pole unit bolts, first install the insulating pull rod and manually perform several slow opening and closing cycles. Confirm there is no jamming or noticeable lateral deviation before final tightening.

c. Never apply external force to the pole unit. During copper busbar connections, do not forcibly pull or stretch the busbars against the pole terminal. Stress generated by the busbars will transfer into the interior of the pole unit, potentially damaging the arc extinguishing chamber. Busbars should be precisely machined to ensure natural alignment without forced adjustment.