Thyristor-based Non-contact Switch
Jan 22, 2026| What is a thyristor-based non-contact switch?
A thyristor-based non-contact switch consists of high-power anti-parallel thyristor modules, photoelectric isolation circuits, trigger circuits, protection circuits, heat dissipation devices, and more. It is used to control the switching of capacitive loads in low-voltage 400V systems. It features no inrush current, no overvoltage, operates silently, allows frequent switching, and is easy to install and wire. It is particularly suitable for use with fast-switching SVC low-voltage dynamic reactive power compensation devices.
What are the characteristics of a thyristor-based non-contact switch?
Non-contact switches offer superior electromagnetic compatibility, reliability, and safety compared to contact switches, making them incomparable. Since non-contact switches are controlled by thyristors, their conduction and current interruption occur within the PN junction, eliminating sparks. This addresses the drawback of sparking during contact switch operation and prevents misoperation caused by sparks due to excessive current or air breakdown in high-voltage circuits. Non-contact switches also exhibit excellent high-voltage resistance. For instance, during the startup of large motors, the inertia of the rotor transitioning from a stationary to a rotating state is immense, resulting in extremely high startup currents (essentially equivalent to short-circuit currents). Similarly, during shutdown, the continued operation due to inertia can generate very high voltages. Non-contact switches are well-suited for such applications.