LG universal system air conditioner Service Manual page 148

Outdoor Units
3.2 Inverter Protection control(1)
3.2.1 Function
: Controlling total power current to protect power semiconductor devices from burn-out by the low current
(including connecting mistake) and over current.
3.2.2 Operating process
1) Detection : check the output DC voltage of Current Transformer(CT).
2) Current Transformer Sensing Error
a) In initial power input, if the CT output is over 4.0V (25A) it shows Self-Diagnosis
Error Mode 40 (defect in CT sensing)
3) CT 1 detection :
a) If total current exceeds CT1 value.reduce 1 step of operating Hz.
- Step down 10Hz from current step.
- If new Hz is below (cooling : Fc min,, heating :Fh min), then turn off the compressor.
b) After step down,if the total current exceed i1 for more than 5 sec. then step down 1 more step.
c) If the current continue below i1 for more than 1 min.,return the Hz to setting Hz.
4) CT 2 detection :
a) If total current exceeds CT2 turn off compressor.
And after 3 min turn on the compressor and check the current again.
b) If CT2 occurs 5 times in 1 hour,stop the operation and shows Self-Diagnosis Error Mode 22
Model
12k
18k~36k
48~60k
148 Universal System Air Conditioner
cooling heating
(CT 1) (CT 1)
8A
11A
13A
CT 2
9A 11A
12A 14A
14A 16A