Solution to the Closing Bounce of Vacuum Circuit Breakers

The closing bounce of vacuum circuit breakers is a common but strictly controllable issue, as it can intensify contact wear, generate overvoltage, and affect both electrical and mechanical lifespans. The following are systematic solutions and approaches:

Mechanical structure optimization (fundamental approach):

Operating mechanism optimization: Ensure that the output characteristics of the operating mechanism (such as spring mechanism, permanent magnet mechanism) match the load characteristics of the circuit breaker. The closing terminal velocity should not be too high and should be as gentle as possible while ensuring reliable closing. Buffer design: Add or optimize hydraulic buffers or polyurethane buffer pads at the end of the moving contact movement or at the transmission link to absorb the remaining kinetic energy, which is one of the most direct and effective methods to reduce bouncing. Improve coaxiality and verticality: Ensure the coaxiality of the moving and static contacts in the arc extinguishing chamber, as well as the centering and verticality of the output rod of the operating mechanism and the moving contact rod of the arc extinguishing chamber, to reduce lateral impact. Tightening and anti-loosening: Check and tighten all mechanical connection parts (such as pins, bolts) to prevent secondary vibration caused by loosening.

Contact System Design

Contact Material and Structure: Use anti-welding and high-conductivity materials such as copper-chromium (CuCr). Optimize the contact shape (e.g., use contacts with a certain arc surface) to facilitate sliding contact and reduce direct collision and rebound.

Contact Pressure Spring: Optimize the preload, stiffness, and installation method of the contact pressure spring. Increase the initial contact pressure appropriately and ensure that the spring can quickly dampen vibrations.

Contact Travel and Overtravel Adjustment: Precisely adjust the overtravel. Insufficient overtravel may lead to insufficient pressure and increased bouncing; excessive overtravel may increase collision energy. Fine adjustments should be made in accordance with the manufacturer's technical specifications.

Control and Operation Parameter Adjustment

Closing Voltage Control: Ensure that the closing coil operates at the rated voltage. Excessively high voltage will result in excessive closing power and speed, intensifying the bounce.

Closing Phase Control (Optional): For high-end or intelligent circuit breakers, phase selection closing technology can be adopted to close near the zero-crossing point of the voltage, reducing the electrodynamic impact of the pre-breakdown current on the contacts and thereby indirectly reducing the bounce.

1. Diagnostic Measurement: Firstly, use a mechanical characteristic tester to quantitatively measure the existing bounce time (usually in milliseconds, ms) and the number of bounces.

Consider Systemic Upgrade: For frequently operated or critical applications, if the old model has inherent design flaws, consider upgrading to a new model of vacuum circuit breaker with better bounce performance.

2.Core standard: The final solution should ensure that the closing bounce time complies with the requirements of relevant standards such as GB/T 1984-2014 "High-Voltage AC Circuit Breakers" or IEC 62271-100 (typically ≤ 2ms). In actual operation, it is essential to refer to the specific technical manual of the equipment manufacturer.

VTZ-12KF Fast Vacuum Circuit Breaker (Tongzhong Electric special model) is an indoor switchgear for rated voltage 12kV, AC 50/60Hz. It adopts modular operating mechanism and is suitable for various industrial and mining enterprises and power grid equipment. The trolley unit is used in conjunction with the KYN28A-12 switch cabinet. It can also be used as a fixed unit and equipped with corresponding mechanical interlocking for XGN2 and other fixed cabinets.

1.Rated Voltage：12kV

2.Rated Frequency：50/60Hz

3.Rated current ：630/1250A

4.Rated short-circuit breaking current：25/31.5kA

5.Rated-short-circuit making current (peak)：63/80kA

6.Installation method:center-mounted trolley or fixed cabinet

7.Applicable cabinets:KYN28-12 series switch cabinet, XGN fixed cabinet, HXGN series ring network cabinet

8.Products comply with standards: GB/T1984, GB/T11022;