Explanation: Retardation test is used for finding the stray losses.
What are different methods of calculating efficiency of DC shunt machine?
INDIRECT METHOD OF TESTING:
In this method, the losses are determined without actual loading the machine. If the losses are known, then efficiency can be determined. Swinburne’s test and Hopkinson’s test are commonly used on shunt motors.
What type of tests are performed to determine efficiency of DC motors?
Swinburne’s test is the most commonly used and simplest method of testing of shunt and compound wound dc machines which have constant flux. In this test the efficiency of the machine at any load is pre-determined. We can run the machine as a motor or as a generator.
How can the speed of a DC motor be controlled?
Thus, the speed of a DC motor can control in three ways: By varying the flux, and by varying the current through field winding. By varying the armature voltage, and the armature resistance. Through the supply voltage.
What power is lost in the stator?
Motor power flow
Power is then lost in the stator circuit, and the stator core. The remaining power is transferred to the rotor. Deducting the rotor losses, one obtains the power converted to the mechanical system.
What are the 2 main types of losses in a motor?
Intrinsic losses are of two types: fixed losses – independent of motor load, and variable losses – dependent on load. Fixed losses consist of magnetic core losses and friction and windage losses. Magnetic core losses (sometimes called iron losses) consist of eddy current and hysteresis losses in the stator.
What are the characteristics of DC shunt motor?
Characteristics of a DC Shunt Motor:
- Speed-Armature Current Characteristic: …
- Torque-Armature Current Characteristic: …
- Speed-Torque Characteristic: …
- Break in Field Circuit of a DC Motor:
What will happen when DC shunt motor is started with load?
Answer : Starting current will be very high so motor will take more current from supply. It may damage the armature winding.