Four Letters Re: Natural Gas Powered Generators in a Disaster–Their Compressors, and Yours

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Captain Rawles,
I saw the disagreement from the former natural gas industry gent located in Texas about your grid assertions as they relate to potential natural gas outages.

Two years ago in Northern New Mexico there was a multi-day natural gas outage to 30,000 homes and it was due to precautionary measures from Texas, caused by rolling blackouts.  New Mexico made the decision to keep the population centers pressurized since it would be more difficult to get the pressure back up in those areas compared to the smaller yet more remote pipelines in the northern part of the state.  I have friends in Taos, New Mexico that confirmed this for me. – G.P.

Mr Rawles –
You wrote: “Most residential refrigerators normally draw around 12 amps, but the peak load (on startup), expressed as Locked Rotor Amps (LRAs), can be substantially higher.”

That might be true for older refrigerator designs, but is not true for at least some modern refrigerators. We have a large Samsung French door style refrigerator that draws (annual average) only 60 watts. When I read the specifications I could hardly believe it so I ran the fridge on a Kill-A-Watt meter for a couple of months to confirm. Running power
(compressor running) was 120 watts and the VA (what you want to use for sizing an inverter) was 180 VA with the compressor running, but the average over time was right where they claimed at 60 watts. To put this into Amps, the running current is 1.5 Amps, and the average is around 0.75 Amps.

This is not some tiny little fridge but a very large 28 cubic foot model with water and ice through the doors, LED lighting, and lots of nice features.

I am currently building a dedicated solar electric system which with a little bit of luck will allow me to take this fridge totally off-grid. – R.R.

Dear James,
I’ve been repairing refrigerators for several years. It’s true, they do need a bigger [current] than you think compressor to start. One thing I haven’t actually tried, but makes sense. There is a compressor hard start kit, which is often used by us repair guys, when the factory supplied compressor start relay goes bad. The hard start kit contains a big start capacitor, which helps with torque. Now, does that reduce the inrush starting current? I’m not sure, but it would appear so.

If your existing generator isn’t quite big enough to start the refrigerator, might be able to call a refrigerator guy, and ask to have a hard start kit put on. Or buy one online, you are electrically minded.

One of the readers writes about “locked rotor current,” (LRC.) Most of the literature and such that I read, talks about Locked Rotor Amps (LRA.)

Thanks for discussing the subjects few others want to get near. – Regards, C.A.Y.

Hello JWR,
My experience with a 2 kilowatt generator (a Yamaha EF2000iS) avoided all the study of LRA requirements.  Using extension cords and a through-the-wall connection, the little Yamaha runs two full-size refrigerators, a small chest-type freezer and a pellet stove most of the night on a gallon of gasoline.  Readers may be interested that the bearings in the Yamaha are rated for twice the life of the bearings in a Honda. Best Regards,  – D.H.

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