A capacitor switching contactor is an electrical device specifically designed to connect and disconnect low-voltage shunt capacitors. It is primarily used in low-voltage automatic reactive power compensation systems to connect or disconnect shunt capacitors in order to adjust the power factor of the power system. Compared to standard contactors, its key features include a built-in inrush current suppression device and a special contact operation sequence, which are designed to handle the massive inrush current and overvoltage generated during the connection and disconnection of capacitors.
Key Technical Parameters and Selection Criteria
When selecting a contactor, ensure that its parameters match the capacitor bank and system conditions. Key technical parameters include:
Rated operating voltage (Ue): Common values include 380V, 400V, 660V, etc.
Rated operating current (Ie): Must exceed the steady-state operating current of the controlled capacitor bank. Common ratings include 25A, 32A, 43A, 63A, 95A, 115A, 150A, and 170A.
Controllable Capacitor Capacity (kvar): The maximum capacitor capacity that a contactor can safely switch varies depending on the rated voltage. For example, the CJ19C-63 has a controllable capacity of approximately 30 kvar at 380V, while the CJ19C-150 has a corresponding capacity of 80 kvar at a coil voltage of 220V.
Inrush current suppression capability: Typically, the peak inrush current during closing can be limited to within 20 times the rated current.
Electrical and mechanical life: Under rated conditions, the electrical life is typically no less than 100,000 operations, while the mechanical life can reach 1 million operations.
