Protecting Appliances from Short Power Outages

[kenny1999]

Are our common home appliances mostly designed to protect itself against tough and unusual conditions like sudden power outage or very short power outage? (i.e. power goes off and resumes within short time)?

I have an AC unit that it is labelled to suggest not to restart the machine after turning it off within three minutes. I'm wondering what is the reason? Could it stress or damage any parts of the appliance?

Thanks

 

[alan123hk]

I hope the following links can provide clues.

https://www.gplushomecomfort.com/blog/what-does-air-conditioner-says-wait-3-minutes-means/

 

[Tom.G]

I have an AC unit that it is labelled to suggest not to restart the machine after turning it off within three minutes. I'm wondering what is the reason? Could it stress or damage any parts of the appliance?

Yes, air conditioners and refrigerators have a thermal overload sensor on the motors that remove power if the motors overheat or draw too much current for a significant time.

The compressors compress the refrigerant gas, which also heats the refrigerant. In normal operation the refrigerant then passes to a 'condensor', essentially a radiator, to cool it enough to condense it into a liquid.

When the compressor stops, the refrigerant gas that is still in the compressor cools down and some of it turns to a liquid.

Now liquids can NOT be compressed. If the compressor comes back on immediately, the motor can't turn. This causes a high current and also heats the motor.

That is when the thermal overload shuts off, similar to what a circuit breaker does. When the temperature goes down, the thermal overload automatically resets and allows another starting attempt.

Cheers,
Tom

p.s. Handheld Hair Dryers also have a thermal overload, that way if the airflow is blocked the heater is shut off before things start melting.