What is the firing angle of thyristor?

zero degrees
Because the firing angle is zero degrees, the thyristor acts like a diode, and the output voltage is a half-rectified sine wave.

How do you calculate the firing angle of a thyristor?

For zero input power the thyristor firing angle must be α = 180° or 360°, so that the output current will be zero. Therefore, for α = αmax = 180°, the output power Ρο = 0. Therefore, the range of the firing angle α is π 4 ≤ α ≤ π .

What is the relation between firing angle and output voltage?

0° < α < 90°: A firing angle larger than zero means a thyristor will also carry positive blocking voltages. This leads to negative DC voltages and also to a smaller average load voltage of Vload = 0.9 · Vs,rms · cos(α). 90° < α < 180°: The circuit is in inverter mode with power flowing from the DC to the AC side.

What is the effect of firing angle on the speed of motor?

Supply Power Factor: It is evident from Fig. 20 that, the supply power factor decreases as the firing angle is increased keeping motors’ speeds constant. Fig. 21 that, the motor current ripple factor of M2 increases with the increase of either the firing angle or the motor speed N2.

How do thyristors control the speed of a DC motor?

The assembly of thyristors, mounted on a heatsink, is usually referred to as the ‘stack’. By altering the firing angle of the thyristors the mean value of the rectified voltage can be varied, thereby allowing the motor speed to be controlled.

How does firing angle change?

Firing Angle Control: The firing angle control is achieved by varying the time of application of Gate pulses to the SCR. The phase angle of the gate voltage is changed with respect to the anode-cathode voltage. In other words, the gate voltage is applied out of phase with the anode voltage.

What is thyristor speed control?

The Thyristor Speed Controller is designed to control the speed of the a DC Motor/Generator, Model 8211, in both the open-loop and closed-loop modes of control. The Thyristor Speed Controller module contains a thyristor single-phase bridge rectifier installed in a full-height EMS module.