Thanks sir, beautiful explain

Would a simple NTC circuit like this work to limit the inrush current when a 230V AC fridge compressor switches on? I want to reduce the start up current so my inverter doesn’t trip out. If I can’t use an NTC to achieve this, do you know what product or circuit would be suitable? A lot of the prebuilt “soft starter” modules say they can’t be used on a fridge, and I’m not sure why. Thanks for any help 👍

@ke6chris

2 жыл бұрын

The compressor has a starting winding that needs full current and is controlled with a PTC. You need a bigger inverter.

@PVflying

2 жыл бұрын

@@ke6chris thanks for replying Chris. Since I asked my question, I’ve learned a lot more about the compressor “hard start kits” Supco make. It seems it is possible and beneficial to add a further PTC in series with a capacitor and to wire this arrangement it parallel with the existing compressor start capacitor (which itself is controlled with ptc relay). Doing so phase shifts the AC waveform in the brief fraction of a second in which the ptc allows current to flow thru the new capacitor and increases the starting torque of the compressor, hustling it much faster through that first phase of movement in which a high current is drawn, so the inverter is perceives less load. This is the theory - I haven’t tried it yet, but I have a 37 ohm ptc and 150uF capacitor en route and Supco in the US have been selling hard start kits for air con and fridge compressors for a long time now.

@ke6chris

2 жыл бұрын

Sounds good Thanks keep me posted

Which is our maximan allowable current and standy state current?

@ke6chris

3 жыл бұрын

I used 1 Amp for the max allowable current and 7 amps steady state current sorry the confusion. Chris

@worldonscreen

3 жыл бұрын

what is load voltage 1A?

they heat to near boiling pt of water,,, yes