Fridge Freezer Inverter Power requirement!

[ericmark]

Or fridge/freezer was on the blink literally when you opened the door the interior light started to flash but lucky had insurance on it. So out came repair man who condemned it saying where the ice was building up showed there was an insulation (heat not electric) breakdown and it could not be fixed. So new fridge/freezer part paid by insurance.

So first step has always been to monitor usage of power over 24 hours once down to running temperature so at a latter date I can compare to see if starting to use more power.

Amps on run 0.2 old one 0.85 Watts 48 old 170 duty cycle 1% old 7% since only been running 1 hour these figures may change but seems far lower than old one although far bigger and the old figures were when new.

Max watts 129 old one 719 could this be right? Re-checked and yes so out with the book. Seems there is a pair of valves which mean the fridge and freezer are independently controlled and the motor is controlled by an inverter. Circuit diagram given, but very small and too many blocks to work out exactly what it does.

However why inverter control one would expect a compressor has to compress a set amount of gas per minute to turn it into liquid and it would not vary. Only thing I can think of are the valves controlling fridge or freezer mean motor speed must vary.

However run watts 0.43 to 0.48 and seems no change in motor running speed. Maybe not 50Hz but really no idea which is why I am asking. What is the reason for inverter motor control on a fridge freezer?

 

[bernardgreen]

What is the reason for inverter motor control on a fridge freezer?

Most probably to get a high speed motor and thus have a compressor with much smaller compression chambers.

 

[danechip]

Yes. And to have a variable motor control for the conditions at that time, rather than on/off thus making it more economical.

 

[ericmark]

As I said does not sound to be high speed or variable speed. I have worked on large commercial freezers designed for transport where inverters are used. In the main so a three phase supply will always cause the motor to run in the same direction. It also allowed for a larger volt drop than with a standard star delta supply.

So may be it's just to allow for voltage variations be it 220 or 240 it will run the same? Years ago I remember being told when I changed over generators I had to wait 5 minutes before putting the power back on. It was to extent the life of the AC's by allowing the pressure to drop before trying to re-start I was in Algeria.

The bi-metal start inhibit device was rather basic.