Do I have enough power?

Here's the deal - I'm looking at a widebelt sander for my shop and the one I'm looking at has the following; 1 - 25 hp motor (don't know the FLA), 1 - 15 hp motor (again, don't know the FLA) AND a 2 hp motor for the feed motor. I have a 25hp 3ph motor for the start of my RPC and the FLA on it is 61 amps, so let's just assume the FLA on the sander is proportional. Assuming all is proportional, that would bring the FLA on the sander to approximately 95 amps. Now to the power running to my shop. The transformer at the pole is 25kva. The meter is at the pole also and is rated for 200 amps. There is 100' of 4/0 Al wire running to my house where there is a junction box. From there another 150' of 4/0 Al wire running to my shop where I am putting in a new 200 amp panel. This is all single phase power. Do I have enough power to run a 45 hp phase converter, a wide belt sander, lights in the shop (26 x 48 shop with flourescent lites), electric heat in the house (in winter), or am I better off to look at a smaller sander, or pay the electric company mega-bucks to put in 3 phase (perish the thought!!!).

By the way, I'm in North Dakota, (where the wind always blows - maybe wind power would help {ha,ha})

Mick

Based on the information that you supplied, your single phase amp draw would be about 165 amps ( that is if all the motors are fully loaded up ), I would think that your current demand in the winter would be greater than 35amps for electric heat.... So I would say no, for everything in your shop and house to run on a 200amp service.

That's what i kind of figured. so back to the drawing board.
Thanks,
Mick

Actually, I think 100 amps is closer to it.

I think you'd be closer to 100, or 110 amps at the very most on that thing. A 50 horse motor draws 117 amps, so your 45 horse phase converter would draw about the same with all the connected motors loaded down. The thing about it is you may not need a 45 horse phase converter. Your main 25 horse motor would act as an idler if it wasn't fully loaded. So, you might be able to use your existing 25 horse phase converter to start/run the main motor, and the other motors can start, and run using that as a dual idler setup. Unless ALL the motors are going to be fully loaded, the only thing you have to do is supply enough single phase current to get them all spinning. Then they'll all act as idlers for each other. If the motors are going to see heavy loads, that might be a bad idea to run it that way. You just can't start all the motors at the same time, but it would run if it wasn't fully loaded.

Actually, I think 100 amps is closer to it.
JunkyardJ

You are forgeting one thing, you have to convert the total three phase amps into single phase amps...so you have to multiply that number by 1.73, to get the total single phase amps

Don't forget this is a machine than can be run at less then 100% duty cycle. It's not like an irrigation pump that runs at 95% FLA 24/7. If your service is marginal, make a note to run the sander at less than max capacity. Watch the load meter and keep it below 50% (or whatever).

Jobbing cabinet sanding (where the machine is used mostly to level face frames and cabinet doors or thickness a few boards) won't challenge your 25 HP drive motor. However if your application is to reduce wide material to thickness in a production setting then you'll have to experiment watching voltage droop, line conductor temp rise, motor RPM droop etc until you've identified the max allowable operating parameters and keep your useage below the limits you've determined.

Just because a motor says 95 Amos on the label plate doesn't men you will be loading the motor FLA full time. Typically an induction motor runs about 35% FLA at idle and doesn't increase much until you load it to about 50% max shaft torque. Then the Amps creep up in rough proportion to FLA. An induction motor is definitely a non linear devise. Mechanical power Vs VA input is a complex function where a shifting power factor and details of the motor's design play a confusing part.

So my advice is to experiment and wear away a few boards setting local parameters then set a red-line on the load meter.

By the way, have you budgeted electrical capacity for a dust collector? It would take a husky DC to serve this big sander and you can't very well run it without positive dust removal. The belt and works will clog in minutes. Figure about 7 1/2 HP as a start. In fact there might even be a sail switch in the collection duct that shuts off the sander if the air flow falls below a certain value. Look to see.

Forrest addy,
Yes, I have in the budget for dust collection. I still may have to scale down to a single belt sander just to make things a little easier.

Thanks everyone for the feedback. It is greatly appreciated!!!

Mick