The controlled (thyristor) rectifier provides a low-impedance adjustable ‘d.c.’ voltage for the motor armature, thereby providing speed control. … The generator was driven at fixed speed by an induction motor, and the field of the generator was varied in order to vary the generated voltage.
How does a thyristor control power?
Thyristor power controllers are operated with an alternating voltage in single-phase or three-phase. They are controlled by a controller and vary the activation time of the mains voltage for the load. … The thyristor power controller switches 60% of the solid waves to the load while blocking 40%.
How is an SCR used to control the speed of a DC motor?
The speed of DC motor can be control by usingSCRin AC circuit as shown in the below figure. The SCR A and B rectifier, the o/p voltage of transformer T1 and apply this pulsating DC voltages to the armature winding and rectifier “C” supplies similar voltages to the motor field winding.
What are thyristor controlled drives?
Thyristor controlled drives employing both dc and ac motors find wide application in industry as variable speed drives. ADVERTISEMENTS: In the 1960’s, ac power used to be converted to dc power for direct control of drive motors with solid state devices (high power silicon diodes and silicon controlled rectifiers).
Can a DC motor turn both ways?
Simply put, DC motors can turn in either direction (clockwise or counter-clockwise) and can be easily controlled by inverting the polarity of the applied voltage. … If a motor is already in motion, the applied voltage can be inverted and the motor will decelerate quickly, eventually stopping.
Why starters are required in a DC motor?
Starters are used to protect DC motors from damage that can be caused by very high current and torque during startup. They do this by providing external resistance to the motor, which is connected in series to the motor’s armature winding and restricts the current to an acceptable level.
What is SCR and its types?
A silicon controlled rectifier or semiconductor-controlled rectifier is a four-layer solidstate current-controlling device. The name “silicon controlled rectifier” is General Electric’s trade name for a type of thyristor. SCRs are mainly used in electronic devices that require control of high voltage and power.