RC snubber networks for thyristor power control and transient suppression

RC networks are used to control voltage transients that could falsely turn-on a thyristor. These networks are called snubbers. The simple snubber consists of a series resistor and capacitor placed around the thyristor. These components along with the load inductance form a series CRL circuit. Snubber theory follows from the solution of the circuit's differential equation.

Many RC combinations are capable of providing acceptable performance. However, improperly used snubbers can cause unreliable circuit operation and damage to the semiconductor device.

Both turn-on and turn-off protection may be necessary for reliability. Sometimes the thyristor must function with a range of load values. The type of thyristors used, circuit configuration and load characteristics are influential. Snubber design involves compromises. They include cost, voltage rate, peak voltage and turn-on stress. Practical solutions depend on device and circuit physics.

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