quote:

Originally posted by Blume9mm:
Not close to the expertise of others here but I would suspect you don't want to be maxing out the Amps on any generator.

I use the 80% rule for all electrical devices, including simple wall outlets. My Onan 20kw genset has an 84 amp (@240v) main breaker, so I sized it based on using 65 amps. Our AC is zoned (even more so now with Mini-splits), so I can start a couple of AC units with the Onan. Even when we had two main ducted AC units (when the house was built), they were a 3.5 ton and a 2 ton, so I could start one during an outage, and then have lots left over for 120v devices. Cooking is done with a microwave only during an outage.

Finally received my soft start kit from Micro-Air. The part number is ASY-368-X72. This is the unit that is rated for up to a 6 ton unit. My unit is a 5 ton.

The instructions for a basic install were fairly straight forward, since this company primarily sells to the RV market more so than the home market. My compressor, however, had some Emerson management electronics that made it a little more complex. After a couple of emails of my wiring diagram and some pics (Micro-air was very responsive), they told me exactly how to hook it up. I cycled the unit five times as instructed, and it was done.

In short, my LRA was showing about 112 using my Fluke meter before the soft start. After it was installed and all trained up, the unit is showing an LRA of 43. Before, my 14 KW generator couldn't start the A/C. Now, the A/C compressor cycles with just a slight change in the generator pitch. My daughter was even baking bread in the oven today while I was cycling the A/C on the generator.

I don't know why A/C manufacturers don't incorporate this type of technology into their condenser units from the start. Perhaps it's cost, or that this is new. One last benefit, the soft start has bluetooth, so I can see exactly the power freq, live current usage, LRA, faults, right from my phone.

ETA: The soft starter was around $350. Way cheaper than upsizing the generator to a ridiculous size just for a micro-second of high amp draw.

Follow up after six weeks of use:

The Micro-Air soft start is working wonderfully. Starts up my A/C compressor smoothly both on line power or generator power.

My A/C compressor is an Amana 5 ton with an Emerson Scroll compressor. It took me a little time and a call to tech support to get it installed because I have a logic board instead of a simple contactor on my compressor. I couldn't be happier with the way it is performing. My LRA runs 41-43 amps every single startup, or about 36-40% of what it was before. It is nice to have whole-house A/C during power outages.

2800 sq ft home here.I run a 45kw Kohler generator lp gas fed.