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THREE PHASE AUTOMATIC VOLTAGE REGULATOR Issue: Jan 2016
On Site AVR Test procedures following maintenance/repair
Items Required:
Single Phase Variac (Variable Transformer)
Multimeters
Clamp-on Current Meter
Test lamp
'Safebloc' Safety Mains Connector
Following Master PCB Replacement
The AVR should be disconnected from Mains and Load before commencing this test.
1. Connect the Variac input to a mains supply but do not switch on.
2. Connect Test Lamp across Neutral and output of phase under test.
3. Connect the Variac Neutral to the AVR incoming Neutral terminal
4. Connect Variac Live output to the Incoming Mains connection of the phase under Test.
5. UNITS WITH AVS ONLY Using Safebloc, connect (but do not switch on) mains supply live to terminal
marked 'Test Use Only' , situated bottom right of the rear panel. This will supply power to operate the AVS
contactor, switching on the lamp at the output.
6. Reduce Variac output voltage setting to zero.
7. Connect Multimeter # 1 (indicating AC Voltage 600V scale) across variac output.
8. Connect Multimeter # 2 (indicating DC 20V scale) between TP1 (0V), and TP2 (5V).
9. Fit clamp-on current meter around variac live out cable (set to 200A)
10. Switch on power to variac and increase output voltage slowly observing current measurement.
11. Current should rise slowly and be no more than a few amps at 100V input.
12. Switch on supply to AVS Test Terminal. A loud thump will be heard as the contactor pulls in.
13. Set Master PCB Potentiometer P2 fully anti clock wise. Increase variac and check that TP2 reaches about 4.8V
and stabilises when the mains reaches about 120V. Reset LED LD8 should be on, as should the green output
LED LD13, but no others. Adjust P2 for 5.00Vdc.
14. Move meter positive lead to TP4 (7V). Check this stabilises between 6.8V and 7.2V when the variac is
increased to 140V.
15. Continue to increase the variac and the Reset LED (LD8) should go off at approx. 140 to 150V mains in.
The green tap LED (LD5) should come on and then move to the end (LD1). Check the lamp on the output
comes on.
16. Turn P1 fully clockwise (indicates 240V). Turn the variac to 160V in). Check the output is between 210 and
230V ac and that the end red LED (LD1) is on.
17. Increase the variac until the AVR output is 241Vac +/- 0.5V. SLOWLY turn P1 anticlockwise until the output
voltage drops (to approx. 222V). LED LD2 should now be on.
18. Reduce the variac until LD1 comes back on. SLOWLY increase the variac and check that the AVR output
reaches 239 to 241V before dropping. (If not repeat steps 16 and 17 above). Keep increasing the variac and
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