Why is a thyristor used in a DC switching circuit?
DC Thyristor Switching Circuit. The thyristor is a current operated device because a small Gate current can control a much larger Anode current. The Gate-cathode resistor RGK is generally included to reduce the Gate’s sensitivity and increase its dv/dt capability thus preventing false triggering of the device.
How does phase control work with a thyristor?
Phase control is the most common form of Thyristor power control. The Thyristor is held in the off condition — that is, all current flow in the circuit is blocked by the Thyristor except a minute leakage current. Then the Thyristor is triggered into an “on” condition by the control circuitry.
How does an alternating AC supply affect a thyristor?
When connected to an alternating current AC supply, the thyristor behaves differently from the previous DC connected circuit. This is because AC power reverses polarity periodically and therefore any thyristor used in an AC circuit will automatically be reverse-biased causing it to turn-“OFF” during one-half of each cycle.
Why does my thyristor not trigger when I push the push button?
If the value of R G is set too high with respect to the supply voltage, the thyristor may not trigger. Once the circuit has been turned-“ON”, it self latches and stays “ON” even when the push button is released providing the load current is more than the thyristors latching current.
What happens when push button S1 is pressed on thyristor?
Additional operations of push button, S1 will have no effect on the circuits state as once “latched” the Gate looses all control. The thyristor is now turned fully “ON” (conducting) allowing full load circuit current to flow through the device in the forward direction and back to the battery supply.
How is a thyristor rectifier similar to a diode?
Figure 3.1 depicts a full-bridge thyristor rectifier. Its topology is similar to the full-bridge diode rectifier. The smoothing reactor in series with the load reduces the ripple of the dc current and extends the range of the continuous conduction.