Hello my friends.
A person who I know used a 50 ft extension cord to power a small refrigerator. The refrigerator did not turn on.
Next day, when I used a 3 feet extension cord, the refrigerator turned on.
Why did it not turn on with a 50 foot cord? Do you think there was a power loss in the cord line?
How did the fridge know, not to turn on? Is there usually a feedback mechanism in power supplies that can detect an extension cord being plugged in?
Thank you for the answers my friends!

P.S. The extension is not defective because when I plugged a living room lamp, the lamp turned on.

 

Could be a defective cord.

 

Hello my friends.
A person who I know used a 50 ft extension cord to power a small refrigerator. The refrigerator did not turn on.
Next day, when I used a 3 feet extension cord, the refrigerator turned on.
Why did it not turn on with a 50 foot cord? Do you think there was a power loss in the cord line?
How did the fridge know, not to turn on? Is there usually a feedback mechanism in power supplies that can detect an extension cord being plugged in?
Thank you for the answers my friends!

Once the fridge started to draw power and start the motor, a pretty good current draw is expected. Let's say, 5 amps.
Then we'll assume you were using a pretty wimpy extension chord, like 18-gauge. For a 50' chord, that's 100' round trip for the current and, at 0.04 ohms per foot, we'll get 4 ohms of resistance.
Now, the refrigerator expects to be connected to 115VAC, and you have, essentially a 4 ohm resistor in series, that means the chord will drop 5A * 4 ohms = 20v that the fridge won't see. So the fridge only sees 95VAC. It may be programmed not to come on if the voltage is less than 100v when it tries to start up. That way, any stuck bearing or long extension chord or general brown-out condition will not cause the motor to run slow (run hot) when trying to turn the compressor.

 

or a very cheap, under-rated wring, cord. An appliance with an old-school single-phase induction compressor motor(s) has a high start-up current in the main and start winding. High resistance cord/wiring will stall the compressor for insufficient power in both winding but having sufficient start winding (that might have a PTC stall current limiter) current is also critical for starting under a high pressure gas load.

 

The 50' cord would likely need to be no smaller (larger number) than 14 gauge for powering the fridge.
That size is readily available in any hardware store or on-line.

 

Probably the 50 foot cord was indeed a smaller size wire, possibly with three steel strands and 2 copper strands. I have come across some of those. In addition, the connections at the ends may have been very por quality.
I have a 98 foot extension cord that will power a refrigerator very well. It is good quality #12 fine stranded wire. Not much voltage drop at all. ( the cord is 98 feet because somebody accidentally damaged it near the one end. And they had no clue as to how to repair it. So I got it and simply installed a new end connector.)

 

I was working with volunteers to build a new dock for our beach association. There was one undersized (wire gauge) 50’ extension cord that we had to replace because the multiple drills plugged into it wouldn’t operate (too weak).

 

I have a mains electric snowblower that takes up to 15A, so I use a 12 Gauge 75' extension cord to minimize voltage drop.

 

The universal motors used in the snowblower and in plug-in electric mowers are more tolerant of slight voltage drops than induction motors. And I have worn out a few plug-in mowers, never cut a cord even once.
And certainly conductor size and quality matter a whole lot. #14 wire is OK for my mower and tends to protect it from overloads. THAT only happens with universal motors. (I think we have wandered off-topic, sort of.)

 

Why don't you measure the voltage across the refrigerator?