Page 244 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

Table 4
Load
Armature Field voltage in Motor speed in
SI.No Load
voltage in volt volt Voltage Current RPM
(Volts) (Amp)
1 1/4 th
2 1/2 th
3 3/4 th
4 Full

6 Load the motor further and switch ON another lamp (Total load now (500 W + 500W=1000W). Record all the
readings in Table 4. Vary the speed with 1/2th load and observe the readings and record in Table 4.

7 Load further to 3/4th load (500+ 500 + 500=1500W) and repeat step 5 and record the reading in Table 4.
Note : Switch ‘OFF’ the motor instantly, if anything noticed irregular consult your Instructor.

8 If motor maintaining the rated frequency after loading 3/4th load. Load the motor to full load (500+ 500 +
500+500=2000W) condition and switch ‘ON’ all the four lamps . Record all readings and repeat step 5.

9 Press ‘OFF’ switch once it is over and check the readings you recorded.
Note : If the frequency reduced considerably when the motor operates in higher loads; Do not run
the motor. Consult with your instructor.
10 Remove all the connection and supply cables from the motor and supply.
11 Record your observations.

TASK 3 : Reverse the direction of rotation by using DC drive
1 Connect the AC supply to the input and output terminals of DC drive when the output terminals connected to
armature and field of the motor, without connecting load.

2 Switch ‘ON’ power supply main switch.
3 Press ‘ON’ key and note the direction of running (forward direction).
4 Press reversing key and check the changing of direction of rotation of DC motor.

Note : Wait, until the motor will obtain stability and then change the DOR.
5 Press ‘OFF’ key to stop the drive.
6 Turn ‘OFF’ main power supply to DC drive and disconnect the DC drive.

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CITS : Power - Electrician & Wireman - Exercise 94