Zero-crossing Switching Contactless Switch

I. Definition of Zero-crossing Switching
Zero-crossing switching refers to the process of connecting the capacitor at the voltage zero point and disconnecting it at the current zero point.

II. Necessity of Zero-crossing Switching

1. Why connect at the voltage zero point?
Connecting at the voltage zero point prevents voltage differences or superposition between the capacitor and the circuit, thereby eliminating inrush currents during switching. This avoids issues caused by inrush currents, reduces power losses, extends the service life of reactive power compensation devices, and minimizes impacts on other electrical equipment.

2. Why disconnect at the current zero point?
During reactive power compensation, capacitors carry high currents for extended periods. Disconnecting at the current zero point prevents phenomena such as arcing, thereby eliminating hazards that may arise from interrupting high currents.

III. Devices for Achieving Zero-crossing Switching

1. Hybrid switch

2. Thyristor (Silicon Controlled Rectifier, SCR)

3. Magnetic latching hybrid switch