3 phase power

[CLL]

The power company is coming put tomorrow to see what it will cost us for 3 phase power. I have several questions, I have no clue what their talking about. We figured we would use a 300 amp box, 1- 40hp motor, 2- 20hp motors, and probably 2-3 5hp motors. They want to know the primary voltage and secondary voltage for the motors, which I assume would be 220/208, especially on the bigger motors. We haven't bought the motors yet, so that is my assumtion. Any other information I might need to ask about? I am completely ignorant about electricity, so any help will be greatly appreciated.

[Gary_C]

I would strongly suggest you find a local electrician that can advise you on the three phase. It is not cheap to install and some of the decisions that need to be made can be expensive mistakes if you start wrong.

Most likely you should use 480 volts as the primary voltage as the currents will be lower. But that depends on the equipment (motors) you have or will have. You will also need some 120 volt for lighting and control circuits. Perhaps that is what the power company is asking.

I do have an extra 50 hp motor from a machine I am parting out. PM me if you are interested.

[bck]

I would strongly suggest you find a local electrician that can advise you on the three phase. It is not cheap to install and some of the decisions that need to be made can be expensive mistakes if you start wrong.

I have a friend a few miles from here that had 3 phase run to his shop a few years back. There was 3 tractor trailer wrecks within a year , over 5 miles away from his shop and each time the truck took a light pole out he would lose a motor on one of his saws. Just the other day he was showing me the surge protector that the power company put in his shop to try and fix the problem. He said they sent him a bill for over $3500 for the surge protectors, not counting the BIG bucks it cost him to get the power company to furnish him with 3 phase to start with.

[Bibbyman]

I would strongly suggest you find a local electrician that can advise you on the three phase. It is not cheap to install and some of the decisions that need to be made can be expensive mistakes if you start wrong.

I'll second that! 

A couple of points...

There is a lot more to selecting motors than picking the right color, voltage and HP.  There is such things as service factor - that is, if the motor is under continuous load or starts and stop frequently.. or if it has to start under heavy load or can start with no load and then have a load applied after it's running.

I suspect a lot of the larger motor can be wired for the higher or lower voltage - depending on how you arrange the tap leads out of the motor.  The motor on our Wood-Mizer mill is that way and I've got motors on other equipment that has that feature.

One smart thing I did with I had 3ph put in was to install a "power lug".  It's a big terminal block with many connection lugs. This way when I wanted to add another circuit,  I just had to go to that power lug and add it.  Since I first went 3ph,  I've added three more machines. 



The box in the upper left has the "power lug" in it.

One other thing.  You probably have some industrial contractor in your area.  They likely have a bone yard of old power distribution panel boxes, motors and breakers, etc.  While I like to go new,  used could save you a bundle.

[trim4u2nv]

Try to have the service ran 480 volt.  You can use much smaller wires to all your motors.  If you want to run 120v lights you can buy a lighting transformer to run your lights and low voltage stuff.  208 and 240 lights can be found very cheaply with a little snooping around. Remember on 3 phase billing your meter bills on the highest reading phase.  If you put all lighting on just 1 phase it reads higher than if the load is evenly divided among the other phases.  Unbalanced single phase loads can skew your billing.   Also phase loss protectors will prevent your motors from single phasing and burning up.   Sometimes an open delta can be cheaper than conventional delta (2 transformers versus 3 transformers.)  However open delta can cause huge imbalances and burn up motors.  Best if you can get 3 live phases and a neutral wire.

[CLL]

Thanks to all for the information as it sounds like the power companies will give you expensive stuff you might not need. I'll pass this information on to my son and let him find a good electriction

[ronwood]

CLL

I had 3 phase installed in my shop by our electric coop. I cost me around $750.00 (from pole to meter base) to put it in. They had to set one pole. The cost will very quit a bit depending on the electric company.

I have 240 volt 3 phase delta. If I had it to do over I would go to 480 Volts which I can still do in the future.

I would for sure talk to a license electrician. Also the cost of equipment (fuse panel, etc ) are more. I bought panel used from  a place in St. Lous. If you need a name or number let me know.

Ron

[Woodwalker]

Each situation is different as to load, distance and what facilities are existing. I can't say just how your provider will handle this but I can tell you that the folks I work for would require you to know how many of what Hp. motors you will operating;; some sort of approximate run time per day per motor and a voltage at which  you wish to operate. A qualified electrician can size your equipment and prepare a load data sheet for you. With that information the power company can then advise you of the available voltages and costs to you to supply your projected load.  Without the correct load data, anything else is just conjecture.

[CLL]

Electric company showed up today and left a list including power of motors, ect. We have an electric motor shop in town and he is helping us as well as the man wiring the building. Thanks for all the help guys.

[dewwood]

I do not know what your operation is but have you considered a phase converter?  If you are running continuously every day and have three phase available that would probably be best but if you are running intermittently or the three phase is not close to you it might be a lot cheaper to go to a converter which only costs you when it is running.  Most three phase installations have a minimum charge each month plus usage.  In my case a converter is much cheaper because I only pay for the extra when I am running the converter and I run it all through my main entrance which costs less per kilowatt hour the more you use.  The 110 then is not an issue either as you can just pull it off of the same main entrance.

[SPIKER]

hey CCL:

not sure but probably late to post regarding this if they were coming out the other day but figured I would anyhow..

480 is better for motors, runs requires less current and less heating, smaller wiring required.  lighting can be 277, (which is 1 leg of 3 Phase Y to Neutral/ground.)   You will need some lighting contractors and or switches rated for 277 volts but are available.   

Motor wise most 3 phase larger frame motors can be wired for 240 or 480 with a minor wire hook up change.

just bear in mind you will need a transformer to run 120/240 items as suggested, these are not too bad now as prices have came down a lot, even better is to buy one 2nd hand at local used machinery shop/industrial equipment depot/recyclers.   also same for 3 phase 120/240 panel boards/distribution panels.   
If you buy used transformer then you need to make sure you get a 240/120 4 wire "Y"  WYE unit, there are 208/240 ones where you can not use all 3 legs as single phase 120, one leg will be a high leg (208Vac) to Neutral. which is usually a Delta (TRIANGLE) wired ones.

dont forget that all the motors will require motor starters & over load circuits, with possible different control coil voltages.

markM

[ARKANSAWYER]

  Man are you fixing to drop some coin.   ;D  Mine is a 400 amp 480 service and I bought most of mine at an auction for $120 bucks.  Then spent $600 just for the wires to get from the box to the top of the weather head.  It adds up quick.  Do it wrong and they will not hook up.

[cheyenne]

Remember 3 phase is a demand based service meaning when you fire everything up it records a peak. Your rate will be calculated at peak of service. Make sure your boards are balanced. There is a device called an Energy Management Control System which is a small black box with a computer in it that will take your demand and spread it out over a 30 day period. Thus saving you a ton of money because your demand peak will be greatly reduced but the utilities will not admit they exist or inform you of them. And yes they are legal. Good luck on your endevor.....Cheyenne