The control box on my irrigation well just blew up. Oil from capacitors all over, and melted wires, lots o' smoke - nice little electrical fire. The pump was just plain drawing too much current. This is the third major meltdown.
I'm going to upgrade to a 20 horse three phase pump. I'm sure it will run on
440. I only have 220 single phase service on the place.
I'm looking at a 30 hp inverter (oversize because 1 phase input and 30 horse is only pennies more than 25). This will give a soft start and allow me to slow the pump down if I need less water.
What should I look for in a 220 to 440 transformer? Especially what size do I need? Anyone know an inexpensive source?
I also could use advice on motor contactors and fusing for this rig. This is a little out of my league.
First thing you need to do is call your local utility, and ask them what it takes to get a 100A or 200A 480V 3ph Delta "Well Service" installed - do it once and do it right. You actually have a water well, so they really can't argue why you need it, though they might charge a bit to put in a new transformer rack to feed it. It should end up cheaper than playing with phase converters in the long run.
(Go as oversized as they'll let you on the panel feed. After it's all in and permitted, then you can add another fused disconnect and run the 3Ph feed into your shop/work barn for the equipment... ;-)
I wouldn't mess with inverters or converters, just a simple 3-phase well control panel with power meter, main disconnect, magnetic starter, and a pump protective device like a Coyote panel.
These provide both overload and underload protection, saves burning up the pump in case you overdraft the well dry temporarily (has an adjustable time delay that will start it again). And you can always install a "Screw protecting the pump, I need all the water I can get NOW!" switch to bypass the Coyote in case of a fire.
A well is going to be starting and stopping a lot, and must be reliable - especially if you count on it for fire protection water. We have a customer who has seven wells and three lake pumps on a ranch, and IIRC 5 of them are 3-phase - one well and two lake pumps
480V and the rest 240V (one oldie is cornerground delta).
The 5 HP lake pump had to be bumped up to 480V because it's out
1,500 feet plus from the service, the wires weren't sized properly for the 208V Y they were running it on, and it simply couldn't handle the voltage drop. Several "Magic Smoke" incidents happened before they were convinced, but they said buying new motors every week was still cheaper than irrigating with city water.
Have you called and asked them? And gotten high enough up the managerial food chain till you have reached someone who is authorized to say yes, explained the situation - and they still won't?
EVERY electric utility I know of uses three-phase for their high and medium voltage distribution systems, and all the interconnections between utilities. They may only send two phases down the "last mile" for your location (or one and a ground if they use Y hookups), but if you follow the pole line back to the main road there *will* be all three legs available there. Unless they have some /really/ screwed up system engineers... :-)
They may want to charge you a fee to extend the third phase wire up the pole line to where the well is, and for a new rack of transformers to drop the 2400V-4800V-9600V-18KV-34.5KV line down to 480V (plus the usual primary fuse rack and other "stuff" you need). It'll take the local line crew a few days - or weeks if we're talking several miles of "hike to them" poles going over rough terrain.
Considering the REA programs were set-up to get universal electric service into faraway prairies and hollows that the commercial utilities didn't want to bother with as "unprofitable", that fee should be a fraction of the actual costs, and they make it up on the monthly rates.
If you are running from Single Phase, 20 Hp, maybe you should think about getting one of those flywheel one or two cylinger gas engines used in the oil patch for running pumpjacks. Last forever, run from propane or natural gas. Use the electric line to run the starter.
Allen bradley, Toshiba and others make boxes that will run a three phase motor off single phase. You will loose a lot of power with only single phase input, but a 50 horse three phase motor might become a reliable 20 hp variable speed with one of these boxes.