Speed control of Three-phase Induction motor using Three-phase cyclo-converter.

Experiment No.: 26

Aim of the Experiment:
Speed control of Three-phase Induction motor using Three-phase cyclo-converter.
Objective:
Measurement of different parameters experimentally such as speed, torque, current of Induction motor drive.

Apparatus Required:

Sl. No	Name	Specification	Remarks
01	Three-phase Induction motor controller using cyclo-converter Kit		01 nos.
02	Three-phase Induction motor with spring load	0.5HP, 230 V, 5A 1400 rpm	01 nos.
03	CRO		01 nos.
04	Tachometer	Digital Type	01 nos.
05	Three-phase Auto-Transformer	10KVA	01 nos.

Circuit Diagram:

Theory:
                   Cycloconverters are basically frequency conversion devices and transform higher frequencies to lower frequencies. The alternating voltage at supply frequency is converted directly to lower frequency without any DC intermediate stage. The advent of thyristors and sophisticated transistorized control circuitry have made them very popular for industrial applications. In the given setup, six SCR based full bridges are connected to the load. Microcontroller based firing circuit provides pulses for the group of SCRs. Using PWM controller we can change firing angle of thyristor.
Procedures:

1. Connect Main supply to Three-phase Auto-transformer.
2. Connect main three-phase supply to ZCD of the trainer kit.
3. Connect output supply from three-phase auto-transformer to trainer kit.
4. Connect R1 to R1A, R3 to R3A, Y1 to Y1A, Y3 to Y3A, B1 to B1A, B3 to B3A terminals using patch chord.
5. Connect PWM input from PWM controller.
6. Connect all the R2, Y2 & B2 terminals for create the star configuration in transformer.
7. Switch on the power using power ON/OFF switch.
8. In LCD display 1:1, 1:2, 1:3, 1:4 mode will display, select any one by using S3 & s4 switch.
9. Now increase the firing angle by using S1 switch & take readings as per observation table.

Observation Table: With No-Load

Sl. No	Output Frequency (f) in Hz.	Output Voltage (V) in Volts.	Firing Angle	Speed (N) in RPM	W1 in Kg.	W2 in Kg.	W=(W1-W2) in Kg.	Torque (T) in N-m
1	50Hz
2	50Hz
3	25Hz
4	25Hz
5	16.5Hz
6	16.5Hz
7	12.5Hz
8	12.5Hz

Observation Table: With Load

Sl. No	Output Frequency (f) in Hz.	Output Voltage (V) in Volts.	Firing Angle	Speed (N) in RPM	W1 in Kg.	W2 in Kg.	W=(W1-W2) in Kg.	Torque (T) in N-m
1	50Hz
2	50Hz
3	50Hz
4	50Hz
5	50Hz
6	50Hz
7	50Hz

Conclusion:
Written by Student.