MOTOR CONTROL & CONTROL CIRCUITS

INTRODUCTION

Motors are the most commonly and widely using electrical equipment in industry. They are the most common prim mover for many mechanical devices. Motors can be classified as AC or DC motors which are driven using AC or DC current. Father classification can be given as bellows. In this Industry, there are five DC motors using for drive weigh feeders because speed controlling is very easily done. But with the introduction of VSD’s all DC drivers are replacing with wound rotor induction motors and still squirrel cage induction motors are using for when needed high starting torque and high power.
Control circuits use to operate machines automatically by using limits and sencers. The circuit can design according to operation of the machine. High power motors are also started using Control circuits.so; function of the control circuits can describe using starting method of the motors

SLIP RING MOTORS

The slip ring or wound rotor motor is an induction machine where the rotor comprises a set of coils that are terminated in slip rings to which external impedances can be connected. The stator is the same as is used with a standard squirrel cage motor. By changing the impedance connected to the rotor circuit, the speed/current and speed/torque curves can be altered. The slip ring motor is used primarily to start a high inertia load or a load that requires a very high starting torque across the full speed range. By correctly selecting the resistors used in the secondary resistance or slip ring starter, the motor is able to produce maximum torque at a relatively low current from zero speed to full speed.

WOUND ROTOR INDUCTION MOTORS

These are the most widely used motor type in industry. Low cost, less maintenances requirements, Reliable operation, wider availability, Easy to rewind. The terminal box of this motors have six terminals, actually they are the both ends of thee windings. By these terminals we can connect the winding as a delta connection or a star connection