Voltase hobby

In the given Block and schema diagram of a 3 φ Full Wave Controlled Rectifier schema to control DC shunt motor is shown.

In this schema diagram the field and armature diagram are connected through three phase full wave Controlled rectifier schema.

In three phase supply, each phase is different form other one in 120°, therefore at each out put terminal a, b, & c give the following Sine wave voltage.

 

Through the three phase controlled rectifier, the three phase supply is converted to a DC and provided to the armature and field of the DC shunt motor.

Through the 3φ full wave Controlled Rectifier, the 3φ AC supply converted to a DC voltage and provide to the armature and field of the DC motor, which flow in shape of T_A (Armature Current) through the ckt (DC motor) due to this controlled Dc the motor start in low speed.

If the DC motor start through ordinary way, then an external resistance is connected in the armature ckt, these resistors in armature ckt controlled the speed of the motor, (Gradually decreases the resistance form the armature ckt) and when total resistance (Resistors) remove form the armature ckt, the motor is rotate at its full speed (RPM). The main purpose of the resistance with the armature ckt is that, to match armature current with internal current (emf) to decreased value.

In case of the controlled rectifiers the resistors are not connected because at motor starting time the SCR connected in armature ckt set the delay angle value ,that the armature resistance controlled the voltage drop in the armature. The armature controlled method is mostly used as compare to the field controlled method,

In armature controlled method the field voltage is kept constant, while the armatures voltages changes.

In the given ckt rectifier converted to the in put DC supply (Full wave) , the rectifier is consistof SCRs , the out put of the SCR is Directly apply to the Armature in a variable shape. The applied voltage can be change form the changing the firing angle of the SCR.