08-05-2012, 04:52 PM
TRANSFER FUNCTION OF ARMATURE AND FIELD CONTROLLED DC SHUNT MOTOR
51355420-LAB-MANUAL-FOR-E-E-CS.pdf (Size: 523.09 KB / Downloads: 43)
PRECAUTION
1. The motor field rheostat should be kept at minimum resistance position.
2. The motor armature rheostat should be kept at maximum resistance position.
3. At the time of starting, the motor should be in no load condition.
PROCEDURE
To find out Inertia Constant (J)
1. Connections are given as per the circuit diagram.
2. The DC supply is given by closing the DPST switch.
3. The DPDT switch is thrown into position 1,2.
4. The motor is made to run at the rated speed by adjusting the field rheostat.
5. The DPDT switch is brought to the original position 0,0’. The time taken for falling of
speed from 1500 to 750 rpm is noted.
6. Once again the DPDT switch is thrown into position 1,2. Then the motor is made to run at
the rated speed
7. Then the DPDT switch is changed into position 1’, 2’.
8. Then J and f is calculated by using the formula.
EC2259 Electrical Engineering And Control System Lab Manual
Prepared by G.Panneerselvam, Vel Tech Multi Tech
To find out Torque Constant (KT)
1. Connections are given as per the circuit diagram.
2. The DC supply is given by closing the DPST switch.
3. The field current is kept constant.
4. The motor is made to run at the rated speed.
5. The various values of Ia spring balance readings are noted
6. Torque is calculated and plotted from the graph by adjusting the slope, torque constant KT is determined.
To find out Back Emf Constant (Kb)
1.Connections are given as per the circuit diagram.
2. The motor is made to run at the rated speed.
3. At rated speed the supply voltage and armature value readings are noted.
4. The Back Emf constant is calculated.
To find out Armature resistance (Ra)
1. Connections are given as per the circuit diagram.
2. The DC supply is given by closing the DPST switch.
3. By adjusting the loading rheostat the various values of Ia and Va are noted.
4. The armature resistance is calculated by the application of formula.
To find out Armature inductance (La)
1. Connections are given as per the circuit diagram.
2. Using single phase variac the supply voltage is varied.
3. The corresponding reading of Ia are noted for different values of applied voltage
4. Then Za and La are calculated by using the formula.