Input Current Control - LG Single "A" Service Manual

5. Input Current Control

5.1 Function
Controlling total current to protect power semiconductor devices from burn-out by the low current (including connecting
mistake) and over current.
Operating process
1. Detection : check the output DC voltage of Current Transformer(CT).
2. Current Transformer Sensing Error
1) In initial power input, if the CT output is over 4.0V (25A)
it shows Self-Diagnosis Error Mode 40
(defect in CT1 or CT2 detection)
5.2 Operating process
CT 1 detection :
1) If total current exceeds CT1 value, reduce inverter operation by 1 step.
- Step down 10Hz from current step.
- If new Hz is below minimum Hz of operation (cooling & heating), then turn off the compressor.
2) After step down, still if the total current exceed CT1 for more than 5 sec.
then step down inverter operation by 1 more step.
3) If the current continue below CT1 for more than 1 min., return the to setting step Hz.
CT 2 detection :
1) If total current exceeds CT2 turn off compressor.
And after 3 min turn on the compressor and check the current again.
2) If CT2 occurs 5 times in 1 hour,stop the operation and shows Self-Diagnosis Error Mode 22
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Part 3 Control logic
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