Converting KW/hr to amps

[Ingenieur]

P=Tω


I fully understand both of those points. Except that there are no Imperial units for Volts, Amps, etc. so you have no choice for those.

But this is off topic so let's stick to that.
Put simply, there is no direct conversion for kWh to Amps.

and where does this factor in size or displacement ?
the point he was making
' it takes a bigger engine '

if you know hours, voltage, pf, and ph there is a calculation
I do not think he was looking for a conversion constant but a reasonable method of calculation and assumptions?

 

[Besoeker]

and where does this factor in size or displacement ?

Irrelevant to the OP.
Can we stick to that please?

 

[ggunn]

Not at all. Typical house needs between 16 and 22 KW. 54 and 60 KW units were referenced here to a post that mentioned a 225 amp service that was more or less fully loaded.

The only things that would overload a generator in the 16 to 22 kilowatt range is an on-demand electric water heater or multiple HVAC units/ electric back up heat. If either of those are present, they can easily double the size of the generator needed to run the house.

Well, OK, but that assumes that the HO wants to roll merrily along after a disaster as if nothing has happened. It it were I, I'd buy a smaller (cheaper) generator and shave some loads until the crisis has passed. That seems more cost effective to me.

 

[Coppersmith]

What exactly does that mean? Having the word peak in there makes it a little confusing.

I looked at their electric bill. It lists the average daily KWH by month for the last 12 months. August was the highest usage month at 132 daily KWH. 132 KWH was the peak daily average usage for the year.

 

[Coppersmith]

Now maybe they don't tell him about that big addition they want to add

I didn't mention it in the OP because I didn't want to complicate the scenario, but the HO is in fact adding a large addition which will have to be added to whatever size generator I can determine is needed to power the existing home. The addition will be two bedrooms, a sitting room (with TV, probably huge with surround sound) and a detached two car garage.

 

[Coppersmith]

You are likely looking at resi grade machines such as Generac, Briggs and the like that are not exactly real robost machines to put it kindly.

The current thinking (mainly from the GC who is spearheading the genset purchase) is that a Kohler liquid-cooled unit will be purchased.

Is the HO opting for automatic twice monthly 1 hour running of the genset and automatice refueling service ? regular diesel servicing? etc. ?

You need to be concerned with fuel supply. You need elevation above any possible flood level or storm surge. You need physical protection from anything from wind blown debris to falling trees.

Large buried propane tank. I've already suggested to the GC to check into how often propane deliveries can be made during power outages for refueling.

Generator can be programmed to automatically do a test run every week.

The property is on a lake and if you stand at the lakeshore you can see that the property rises up about eight feet toward the far end. The generator will likely get sited about midway and possibly on a raised (several feet) pad in case of rising water. The property is on a 500 year flood area. (But Ellicott City MD is in a 1000 year flood area and it's flooded twice in 2 years!)

even if I add something like a traction elevator!

Oh, I forgot to mention when I was talking about the addition above. They are adding an elevator. I asked GC to get specs on it so we have a good load calc.

 

[Coppersmith]

Well, OK, but that assumes that the HO wants to roll merrily along after a disaster as if nothing has happened.

They do, or at least that's what I'm being told by the HO's personal assistant. The HO doesn't speak directly to tradesmen.

 

[Russs57]

I suspect in the end fuel will be the limiting factor. I’m not up on residential codes but I suspect best you can do is a pair of 1,000 gallon liquid propane tanks provided you can keep them 25 feet from property line. That should put you in the neighborhood of 3 weeks running time on a 30 KW, 1800 rpm, generator (assuming 50% loading).

Some load controls should let this be more than adequate. You are talking about 125 amp service. Comes a point where all parties concerned need to except certain limitations.

Even this reeks of overkill but some want what they want. In your shoes I’d rather offer a solution that will provide enough to get by for a worst case than something that handles 100% of load for only a few days.

I am in a hospital setting. I have been in situations where generators run out of diesel fuel. Now you have all fuel filters plugged, all starting batteries dead, all generators needing to be primed, and no power to accomplish this.....even if you have fuel in the ground....and help isn’t available in theses situations. Don’t even get me started on ATS’s that die along with generator PLC’s that go in these events.

Sorry for the over the top rant. Just that I have lived through more of this than I imagine most have. It is a lot like insurance, you want enough but not at the expense of meeting daily needs.

 

[Russs57]

OMG, the elevator comment was intended as a joke. Hopefully it will be a hydro. When you get into four quadrant stuff and needing to sink power I’m calling a trusted PE.

Have fun my friend. Sounds like an educational ride.

 

[ramsy]

..The property is on a 500 year flood area. (But Ellicott City MD is in a 1000 year flood area and it's flooded twice in 2 years!)..

Where did you get this information? Where do I get it for my house?
Is brush Fire history, tornado, hurricane, or earthquake damage also available?

 

[junkhound]

They do, or at least that's what I'm being told by the HO's personal assistant. The HO doesn't speak directly to tradesmen.

' does not speak to tradesmen'

golly gee there, disregard any technical info, sell them whatever will provide you with the best monthly income for maintenance and excercising the unit. :roll:

 

[Besoeker]

I looked at their electric bill. It lists the average daily KWH by month for the last 12 months. August was the highest usage month at 132 daily KWH. 132 KWH was the peak daily average usage for the year.

That gives average based on one month of 31 days. So some days could be higher. Possibly even much higher. In short, it doesn't tell you much more than what your energy will be for that month. And maybe encourage some energy saving practices.
It won't tell you what maximum power you will have to design for. Power (kW) is an instantaneous value.

 

[Coppersmith]

That gives average based on one month of 31 days. So some days could be higher. Possibly even much higher. In short, it doesn't tell you much more than what your energy will be for that month. And maybe encourage some energy saving practices.
It won't tell you what maximum power you will have to design for. Power (kW) is an instantaneous value.

I agree. The more I read this thread the less confidence I have in any guess. I've already attempted to get the GC to pay me to do a study of the usage. I'll continue to do so. What's the best tool to record amperage over time? Are they rentable?

 

[Coppersmith]

Where did you get this information? Where do I get it for my house?
Is brush Fire history, tornado, hurricane, or earthquake damage also available?

The flood information is available here as a link on the property appraiser's website. Not sure about your area. The last time I personally looked up the information was a while ago for some property I was purchasing. I think it was actually generated by a Federal agency like USGS.

 

[Besoeker]

I agree. The more I read this thread the less confidence I have in any guess. I've already attempted to get the GC to pay me to do a study of the usage. I'll continue to do so. What's the best tool to record amperage over time? Are they rentable?

I had a 'scope with a serial port so I could download a data so that I could download data to my laptop and dump it in an Excel spreadsheet.

I have also rented Dranetz power profiling instruments.
This may help.

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Rent Electronic Test and Measurement Equipment from Advanced Test Equipment Rentals
Advanced Test Equipment Rentals
The Knowledge. The Equipment. The Solution.
800-404-2832 (ATEC) US & Canada
+ 800 0404 2832 International

 

[JFletcher]

' does not speak to tradesmen'

golly gee there, disregard any technical info, sell them whatever will provide you with the best monthly income for maintenance and excercising the unit. :roll:

Yeah, sell him a hundred kilowatt unit ... 50 kilowatts for his house and 50 kilowatts for his ego, I mean, "future expansion".

 

[kwired]

The property is on a lake and if you stand at the lakeshore you can see that the property rises up about eight feet toward the far end. The generator will likely get sited about midway and possibly on a raised (several feet) pad in case of rising water. The property is on a 500 year flood area. (But Ellicott City MD is in a 1000 year flood area and it's flooded twice in 2 years!)

Where did you get this information? Where do I get it for my house?
Is brush Fire history, tornado, hurricane, or earthquake damage also available?

Who was here to record floods 500 years ago? Native Americans maybe, but just how accurate of a record is there?

Florida - some Europeans were there 500 years ago - but this would have been very early on since Europeans first discovered the American continents.

 

[ggunn]

Who was here to record floods 500 years ago? Native Americans maybe, but just how accurate of a record is there?

Florida - some Europeans were there 500 years ago - but this would have been very early on since Europeans first discovered the American continents.

Flood plain data is based on modeling, not so much on historical data. My house is on a hill some 80 or 90 feet above the water level in the river that runs through town. I'll bet I'm in a 10,000 year flood plain.

 

[Ingenieur]

Irrelevant to the OP.
Can we stick to that please?

not really
question was raised why 1800 vs 3600
the comment was made that for P to remain the same engine size must increase
I showed why and how much
you had a problem with my response

 

[Ingenieur]

Where did you get this information? Where do I get it for my house?
Is brush Fire history, tornado, hurricane, or earthquake damage also available?

I think fema has flood plain maps
google some key words

https://msc.fema.gov/portal/search