Not a duplicate question: this question is about reducing start current, not about identifying the motor type.
I have a refrigerator that has a permanent split capacitor (PSC) motor, which I am powering from solar panels/battery/inverter.
My inverter is rated at 1000w (2000w peak), but unfortunately, the motor occationally trips the overload protection of the inverter, with the risk of spoiling the contents of the fridge if it goes unnoticed.
I am considering replacing the motor with a DC compressor (Danfoss BD35F), but it's quite expensive (about $350).
Before I do that, I want to experiment first, to see if I can get it to work with a consistently lower start current.
I realize it might break the motor, that it might not start consistently, but it's worth a try.
I've read about the following options:
- a) use a start capacitor, 150uF, for the first 1000ms
- b) use an NTC thermistor
- c) power resistors, for the first 1000ms (similar effect as NTC)
- d) voltage transformation to a lower voltage, e.g. from 230V to 200V
- a) I'm having a hard time finding a start capacitor to try with, and random experimentation could be expensive, since they seem to cost about $10-15 a piece and can break if powered for more than a few seconds.
- b) I've tried a 10ohm NTC, but that made no difference at all.
- c) I'm going to try with various resistors at 50, 70, 100 ohms (rated at 50w).
- d) I'm not sure which type, which voltage to try etc..
I tested the motor with the following results:
- Disconnected for 24h, ~850w
- Connected for 20min, disconnected for 5min, ~600w
- Connected for 45min which included a self-restart, ~1100w
- Disconnected, then reconnected after 15min, ~800w
I'm puzzled by these results, because it seems that the motor draws more if left connected. But the thermostat disconnects the circuit. The only way this makes sense to me, is if the thermostat somehow causes an arc that draws an additional 300w when reconnecting. But I tested it by disconnecting for 15min, turning the thermostat to 0, reconnecting, then turning the thermostat to 3. The max power draw was only 782w.
Very strange... Any ideas?