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| I am wondering what are the pro's and con's of using a converter to get 3 phase power. The land owners are wanting to put grain bins up on the place but the nearest 3phases is 6 miles away. Does anybody have any simple ideas that I might could run by them? thanks |
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nw pa | what kind of bins??? If there just for stoarge and no drying single phase will work ok. Even if drying if your not going to go over 400 amps of power it will work... That is what we have and while three phase woould be nice if it were here we get along ok. Wouldn't advise running much over a 20 horsepower at one time on it though. We have mostly ten horse and under on the bins and have a total of slightly less than 100 hp. don't try to start them all at the same time. It will suck the lamps from the next door neighbor. have a talk with the power company.. see what they think
Edited by sri 11/22/2008 00:11
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| We have a 600 amp singe phase service to our bin sites. We are running a 15 HP blower, a 15 HP dryer, 3 5 HP bin fans, one 10 HP bin fan and related motors. Everything works fine. This is off of a high line that was put in in 1940. If I was starting from scratch I would investigate a phase converter, but we are gettingalong with no problems.
John EIA |
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| I've got just a system, rather old, and added to piece at a time. With a 400 amp service I can run about 50 hp of motors at any one time. If I was starting over I'd seriously considered 3 phase either from the power company or from an inverter. One down side is the higher cost of single phase motors and the occassional problem with capacitors. Another problem is while you can get a 15 hp 3600 rpm fan motor you're limited to 10 hp on 1750 rpm auger motors. I've got an 8" sweep/truck loading auger that I can't run to full capacity with only 10 hp. I did see where Baldor (very good motors) now has a 15 hp 1750 rpm single phase motor but the list price was $4800. |
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East Central Arkansas | They might want to buy a piece of ground closer to the 3 phase lines to put the bins on. |
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Sac & Story county IA | I have built and used converters for past 20 years. I have a 20 and 25 hp fans running now. ( in the snow storm)
A rotary phase converter or the new inverters will work fine. The 20 and bigger hp inverters are too new to know how long the last but what I have been around have been good. I have had a couple that quit and I don't know why. They were ebay bargains so just get another and don't bother with repair.
Realize that 3 phase power is more complicated than single. On single phase, if one line doesn't have juice, the motor stops. On 3 phase, if you loose a phase when the motor is running, it will keep going but heat. If your thermal overloads are proper, it will probably trip out or not.
If I were to start from nothing, I would probably use a dual idler converter setup, about 2 - 30 hp motors. Then, put the balance capacitors on the load side of the contactor for each motor. |
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Hendricks MN | I have two of the Baldor 15 hp motors, not good motors. Both were replaced once under warranty and I have put in many capacitors plus a couple of transformer fuses. When a motor goes out again it will be replaced with a converter and a three phase motors. |
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Brinkley, Arkansas | John those were my thoughts exactly. It'll probably be cheaper in the long run to relocate the bins and have the electrical capacity for expansion in the future.
Southfork......I don't know anyone in the south that runs the real low hp fans on their bins like the guys up north. If you're going to put rice in them you'll need more air than single phase motors will provide UNLESS you're putting up small bins (small bins = more $$$/bu). Rice is much harder to push air through than corn or beans. I talked to my bin guy the other day and he says the most common bin going up now is a 48' with a 50 hp fan and burner. As warm as we usually are during harvest you gotta get it dry quick or spoilage will be a problem.
Edited by RAB 11/22/2008 10:08
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Sac & Story county IA | "Southfork......I don't know anyone in the south that runs the real low hp fans on their bins like the guys up north."
This cold is good for something.
At least when we get grain in a bin and turn the fan on and it gets damn cold, you won't loose the bin. |
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| Lots of times, electricians will use starters for three phase motors with only two heaters. If the phase that's gone or weak only causes high current in the phase without the heater, the motor will be sure to fry. That's most common when run from an open delta power source that guarantees unbalanced line currents. Open delta transformers sized too close to the motor rating make that worse and some utilities put too small a transformer on the wild leg making that all worse.
Then I've known electrical wholesalers when asked for the heaters for a particular motor current to look up the proper rating and then give the electrician heaters for two steps more current to prevent nuisance trips. But that leads to the "nuisance" of burned up motors without ever tripping the overloads.
Gerald J. |
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| Big motors on a long single phase distribution line need lots of transformer capacity to keep the starting currents from dropping the voltage too far and may need some soft start starters to limit the starting current. And WILL need the transformer close to the biggest motors with substantial conductors to the starters and the motors to minimize voltage drop. 100 feet of wire rated for the motor run current will make for really poor starting just from the voltage drop. Going 6 or 8 sizes larger will help in motor starting a great deal.
The trouble with transformers really close to the bins is that can put overhead wires in the way of augers and the two don't mix safely. It would be better to use pad mount transformers with several hundred feet of underground 7200 volt cable.
Gerald J. |
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| Well there are advantages to 3 phase power ability to use large motors are one of them but if you are on 480v 3 phase the motors are cheaper but everything to wire them must be made of gold the wire is smaller but all the starters and disconects are expensive I mean like a 30 amp disconnect for 480v is over 200 buck where one for single is 15-20 bucks and everything related to 480v is really expensive but I guess I only have to wire it once (hopefully anyway's) Dennis SEND |
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| That's because 480 volt arcs persist and burn the switchgear down where 240 volt arcs quit when the gap opens up. Worse yet a 480 volt arc to ground won't draw enough current to flow a fuse or trip a breaker so it just sits there. That's what makes 480 volt equipment expensive.
Yet 480 volt equipment can use smaller wire and so saves there and the voltage drop of long runs isn't as much of a problem.
I know electricians that have been burned by the arcs of 480 volt circuits and just plain refuse to work on them. Even if their factory has both 240 and 480 volt circuits, they tell the boss to do it.
Gerald J. |
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North central Iowa | E718 any chance you are from Iowa, I would love to hire you to take a look at our dryer electrical set up sounds like you know your way around phase converters? |
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WCIN | I have went throght the same thought. Power company wanted $$55,000 to bring 3-phase 1 1/2 miles. "Bulls**t", I said. I needed and have to replace the leg motor to a three phase with a variable freq power drive. This thing is awesome, slow start and efficient. Toshiba Variable Frequency Power drive. Dial the little knob to vary the speed of the motor it is controlling.
The way I understand. I roto-phase needs to be running at full speed, before turning on three phase motors at full load. The freq drive doesn't matter.
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Sac & Story county IA | I live in Iowa. I will show you stuff I build and teach you anything I know, but I am as busy as I can be during drying time so I don't want anyone depending on me to fix stuff then. |
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North central Iowa | Just thought if you ever swing west of Fort Dodge you could stop buy and take a look at our dryer set up and Ronk pahse converter to see if we are sized right or if we could improve something. Just a thought. Thanks for the reply.
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Sac & Story county IA | West of Ft. Dodge, Calhoun county? I am in Sac county. We can get together sometime.
Nice looking power room.
Email me sometime. The address in profile should work. |
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grain bin with single phase power
