DC Compound Motor
DC Compound motor are special types of motor in which two types of field winding is available.Its one field winding is connected in series and other is connected across the armature.Due to both type of winding in DC Compound motor its characteristics is intermediate of DC series motor and DC Shunt Motor.DC Compound Motor are classified into two categories
Cumulative Compound Motor
if the magnetic flux produced by the series winding assists the magnetic flux produced by shunt then is called Cumulative compound motor.Cumulative compound motor also classified into two categories
- Long shunt type
- Short Shunt type
Long Shunt Compound DC Motor
When the shunt field winding is connected parallel to both armature and series winding then this motor is called long shunt compound motor.Circuit diagram of long shunt compound dc motor is given below.Short Shunt Compound DC Motor
When the shunt field winding is connected parallel to armature winding only then this motor is called short shunt compound dc motor.The circuit diagram of short shunt compound dc motor is given below.Characteristics of Cumulative Compound DC Motor
Characteristics of Cumulative dc motor is given by curve.This curve is draw between two different parameter of compound dc motor.Torque Load Characteristic
Torque load characteristics of cumulative compound dc motor is given below.
From this figure it is very clear that torque developed in cumulative compound dc motor is less than the shunt motor at full load but is greater than the series motor.the starting torque of cumulative dc motor is greater than the starting torque of shunt motor.from figure it is also clear that as load current increases, the torque also increases.
Speed torque characteristics
Speed torque characteristics of cumulative compound dc motor is given below by a curve between speed and torque.
From the given curve it is very clear that at low torque the speed of the motor is very high but as the torque increase the speed of motor decreases slowly.it means that this motor is capable to bear high load but not able to bear sudden over load.
Speed torque characteristics
Speed torque characteristics of cumulative Compound DC motor is given below by a curve between speed and torque.
From give figure it is shown that the speed of the motor reduces as the load current increases.But the speed variation of this motor is intermediate of series and shunt dc motor.
During the starting of differential compound dc motor the series winding is short circuit due to this this motor start as shunt motor with a constant speed .
Differential Compound DC Motor
A compound dc motor in which the series winding so connected that it will oppose the field flux of shunt field winding the this type of dc motor is called differential compound dc motor.Differential compound dc motor are also classified into two type i.e (a) Long Shunt type (b)Short Shunt TypeDuring the starting of differential compound dc motor the series winding is short circuit due to this this motor start as shunt motor with a constant speed .