Home generator - Am I crazy?

[mike93lx]

For funsies here is a 5hp motor a starting and running a grain auger. I’d agree the Vue isn’t all that sensitive from what this shows. Although the motor is oversized to the application and isn’t under a very large load of any kind when it starts. I have seen the Vue show large spikes with things start under load but not usually on this circuit. I don’t have the patience to scroll back far enough to find another example but it will pick up high startup current if the motor starts under a load.

To be clear, I use a Vue as well.

Maybe we are talking about this differently. I'm talking about the inrush current not just a motor drawing a little heavier on startup.

The circuit pictured below is my 1st floor a/c which doesn't have a soft start. This unit will trip my 7kw generator but the Vue only shows a nice, consistent 5a and then (off screen) it increases to 9a in one step. I have the same unit for my second floor and it needed a soft start to be able to run on the generator.

 

[My Old Tools]

Oh that’s weird. Well… ok.

Hey guys, my name is Wes. I’m in the process of building a home and have been thinking about generators. I know what I want, I’m just curious how unreasonable I’m being.

Power needs:

We are building our home, garage (which I will spend most of my time), and a detached home for my in-laws. Most of our power demands will be fed by natural gas. A 200amp service will satisfy both buildings.

My idea:

I could install something like a generac 20kw with a bunch of load shed modules. However, I already have a few ford 300 engines laying around and a ton of parts. I like the idea of staying on that engine platform. I also like hearing 1,800 rpm. Kohler makes 39kw unit with that for motor. 45rs62

I can get a low hour 39kw for about the price of a new generac 20kw. Fuel consumption per kw is comparable. The smaller unit is about 5% more efficient. If I go with the bigger unit, I won’t have to install load shed modules. That is an added bonus. They have been problematic in my experience.

My electrician says I’m crazy. Am I?

My Generac is a 37kw with a 4 cylinder turbo Mitsubishi truck engine. Works great, very efficient.

 

[mm08822]

The load calc may be taking into account motor starting which momentarily requires more power. Your 18kw measurement is probably steady state load.

Any motor always requires some reserve gen capacity for the start-ups. The more frequent that starts are performed, the more important it is, such as AC. W/o it, you can shorten the life of many connected loads.

 

[mm08822]

To be clear, I use a Vue as well.

Maybe we are talking about this differently. I'm talking about the inrush current not just a motor drawing a little heavier on startup.

The circuit pictured below is my 1st floor a/c which doesn't have a soft start. This unit will trip my 7kw generator but the Vue only shows a nice, consistent 5a and then (off screen) it increases to 9a in one step. I have the same unit for my second floor and it needed a soft start to be able to run on the generator.

Lots of filtering going on in the software (and hardware) which is expected as it is a simple residential energy monitoring product. Not really any different than a DVM that is "too slow" to capture peak inrush.

Clean graphs are needed for the residential audience.

 

[mike93lx]

Lots of filtering going on in the software (and hardware) which is expected as it is a simple residential energy monitoring product. Not really any different than a DVM that is "too slow" to capture peak inrush.

Clean graphs are needed for the residential audience.

Absolutely

 

[theoldwizard1]

Any motor always requires some reserve gen capacity for the start-ups.

With a "true" soft starter, the need for reserve capacity is greatly reduced.

 

[PT Doc]

Power could be out for a day or week a few times a year. I has to feed two homes and a septic pump. Neither home will have large amperage draws, heat pump and appliances will probably be the biggest. I do weld frequently.

I know I don’t need the power. I just prefer low rpm generator noise and prefer to stay away from load shed modules. For the price, both options are about a wash. I just don’t see enough of an efficiency loss to go small.

Where are you located that you could be without power for a week?

 

[yhprum]

Yes, you're crazy. That's wildly oversized for what you need in an outage.

Then you came to the right place haha.
I do like the idea of an indestructible engine making quiet power. Screaming generator noise is a bummer.

 

[Max Capacity]

Talk with the Electrician and have him install the Generac with transfer switch, etc.

Mine has been in place for 12 years now. It runs itself for 15 minute twice a month. I can check it from my cell phone app for it.

You want to keep your life easy, make use of the items out there that allow you to focus on other things.

Put the generator out behind a building where you won’t hear it.

 

[KenC]

I would rather have a new Generac or Kohler , even smaller will run everything you need. That used model is a nice unit but 1145 hours??? That’s used a lot

That's roughly equal to 50k miles on a 300 Ford six in a pickup, I'm sure all of us know the reputation of that engine.
One of the reasons I'd consider oversizing that much is the expected dependability of the engines in portables vs a real industrial machine.

I don't think you're crazy, but I don't know the heat pump load nor the expected run times. We had a tornado hit out little city last year taking out hundred of power poles and miles of wire. So some people had no power for a 'l o n g' time. A nice quiet, oversize supply would have been perfect then.

 

[KenC]

I wish grandad and grandad were here to tell me how they got thru the weather in NW Arkansas and Eastern KY before electricity. One raised hogs, and the other helped get tyson chicken going with huge barns of chickens. There was no ac in those barns, the only rule was one had to put on special slippers over the feet to not track in diseases.

No AC, but I've never seen a commercial chicken facility without multiple big fans to keep the inside temp the same as outside. No air movement, sun shining on metal roof, hundreds (or thousands) of bodies burning calories will heat up a chicken house in minutes. Hot chickens die.

 

[Badger97]

Whatever you do, get a Kohler over Generac.