SALIENT FEATURES :
Thyristorised Closed loop speed control of 3 phase Induction.
MOTOR : This trainer is designed for speed control of 3 phase induction motor using V/F method. Voltage control is obtained by 3 phase SCR fully controlled converter and Frequency control is obtained 3 phase SCR inverter. Both voltage & frequency are simultaneously controlled.
This unit consists of:
i. 3 phase fully controlled converter.
ii. 3 phase Mc – Murray Inverter.
iii. PI controller for closed loop.
iv. Motor set – up.
* Three phase fully controlled converter for Voltage
* VARIATION :
* Six Isolated gate signals for Full Bridge Converter.
* Firing Angle variable from 1800 to 00 through Ramp and pedestal control.
* Gated carrier source at 4 KHz.
* Test points are provided on the front panel for detailed study of circuit signals by the student.
* Necessary test points are terminated at sockets so that the student can monitor / measure/study the signals using CRO, DVM, etc.
* One potentiometer to vary the firing angle. monitor all the test points of the control circuitry for correct functioning.
* Six SCR’s each rated at 1200V @ 25 A, Each SCR is provided with RC snubber.
* The SCR’s are mounted on suitable heat sinks and placed inside a nicely designed cabinet.
* Facilities are provided for switching ON and OFF, the AC supply to the converter circuit with fuse and miniature circuit Breaker protection.
* Provided with one Voltmeter to indicate DC Voltage variation.
* THREE PHASE MC – MURRAY INVERTER FOR FREQUENCY VARIATION :
* Six isolated gate pulses are provided to fire the six number of SCR’s.
* One Potentiometer provided to vary the frequency of the inverter from 10Hz – 50 Hz.
* One Potentiometer provided to vary the frequency of the inverter.
* All gate pulses are Isolated by pulse isolation transformer.
* Six SCR’s rated 1200V / 25A provided.
* Six Diodes rated 1200V / 6A provided.
* 6 Nos. of Commutating capacitors and 3 Nos. of center tapped inductors (Rating at 120mH, 4A) provided.
* All 6 Nos. of SCR’s, Diodes, Capacitors & Inductors forms 3 phase inverter with 180o mode conduction.
* DC Input of inverter fed from three phase SCR converter.
* POWER SUPPLY :
* + 15V regulated DC power supply for control circuitry.
* CLOSED LOOP :
* Analog PI Controller provided for closed loop operation.
* MOTOR SETUP :
* One 1hp three phase Induction motor with spring balance load setup.
* One optical encoder is provided for the speed measurement.
* The output of optical encoder is signal conditioned & calibrated to indicate the speed of the AC motor & give feedback signal for closed loop.