Phase Converter

I recently bought a milling machine with a 3hp motor. I purchased a
7.5 hp rotary phase converter and hooked it up to my mill. I have a
100 amp 220 service to my house. Unfortunity I have noticed that when
I first turn the mill on the lights in my shop quickly dim due to
starting of the mill which I understand. My problem is my electric
line is shared with my neighbor then goes to the transformer on the
pole. Another neighbor is also hooked up to the same transformer and
everytime I start the mill the neighbors lights also dim quickly...My
question is due you think I should get the power company to fix the
problem? Do I really need to get a bigger service (200amp) even
though I am only running one machine?
Thanks
Reply to
swbudnack
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The simplest thing would be to get a VFD, which can slow-start the motor. I don't get any blink of the lights when I start my 7.5 Hp lathe!
Putting in a 200 A service may not cause the power company to replace the transformer, depending on its current size.
Jon
Reply to
Jon Elson
Someone else told me about them but are they very pricey? Where could I get them?
Reply to
Carbonite
Do lights dim when you turn on your mill (after you turned on your phase converter), or do they dim when you turn on your phase converter, before you turn on your mill?
In any case, I think, unless you are a heavy user of this mill and start and stop it incessantly, a small inconvenience of lights sometimes dimming does not justify the expense of upgrading your service, perhaps utulity side etc.
With phase converters, you could minimise the effect of lights dimming at startup, if you used Jim Rozen style belt starting phase converter.
i
Reply to
Ignoramus408
you could make your own
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Reply to
Ignoramus408
When I start the phase converter it dims for a second but when I operate the mill thats when the light dim for the neihbors. Its really noticable that I need to do something about it. I also notice when I do turn on the mill, the converter growns alittle, like theres alot of power being used. I sometimes wonder maybe its the converter?
Reply to
Carbonite
Another question would be should I use a VFD unit instead of the rotory phase converter? From what I can tell ,I can ramp up the spindle speed of the mill and would not get that surge.
Reply to
Carbonite
He already has that, he was asking about VFD.
Reply to
Clif Holland
You probably want to talk to the local power utility before you do anything - they probably need to put in a larger transformer at the pole to handle the start surge of that big a motor, when combined with the normal loads of the other houses on the same transformer.
It's also possible that there is a dirty connection or two in the high voltage lines coming into the common transformer, or on the low voltage side where you and your neighbors all hook up. They can send a lineman up there with a voltmeter to look for bad connections.
And another probable source of the problem is the service drop wires to your house. It is common for utilities to chat rather ruthlessly on the voltage drop of service wires - you install 1/0 TW Copper wires up the old mast for a 100A service to allow a bit over the mandated minimums, and they use #2 XLPE Aluminum service wire up to the pole. Sure, there's a lot of voltage drop in the circuit from that service wire, but they're the utility and they can do it - and save some money on wire in the process.
Myself, I'd change the main service and riser to a 200A Copper-buss service panel as the first step, to minimize any voltage drop problems that may be in your equipment - and if your old panel is over 20 years old, it's probably due anyway.
If you've done any major square- footage additions to your house, you might even jump a notch to a 400A service, then when you get that great deal on a Lathe you are still OK.
(I have to do that myself - bump up from an old 200A fused-switch main service to a 400A. But I've already reworked the main breaker panel, the 200A was a bit oversized when it was installed, and we've converted the kitchen, water heater and clothes dryer from Electric to Gas to ease the load. See "Shoemaker's Children Go Barefoot...") Most home builders make the main panel as small as possible to save money, a 100A or 125A panel, or a 70A "Crowfoot" (six breakers, no Main) in the older days. And then over the years you've gone and added on one or two bedrooms and a Den, and central air conditioning, and a big swimming pool/spa with a 1.5 HP filter pump and a 2 HP spa booster, and a microwave oven, and a toaster oven, and that big-screen entertainment center, and a computer and laser printer...
The conversion of your garage into a home shop with the upgraded lighting, and the fans, and the 7.5 HP rotary phase converter and 3 HP mill, and the 50A welder outlet - that's just the last nail in the coffin. If this sounds a lot like your house, I can guarantee that you need to upgrade the main service.
Make sure that you generously oversize all the wires - use 4/0 or 250MCM Copper for the 200A mast riser where 3/0 THHN would do, and oversize the wires heading into your shop sub-panel and the phase converter the same way.
The Electrical Codes are a /minimum/ standard - there's no rule at all against doing a better job than you have to. ;-)
And get the utility to use the right sized riser wires to the pole, too - they'll grumble about it, but if you twist their arm you can probably get them to break out the 250MCM or 350MCM Aluminum wire.
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Reply to
Bruce L. Bergman
This doesn't sound right to me. Talk it over with the power company and see if you can get them to check the situation out.
Steve
Carb>When I start the phase converter it dims for a second but when I
Reply to
Steve Smith
I read a number of the other posts and don't disagree with any of them. But since your neighbors get the dimming, too, I'd go to the utility company right away. You are going to have to do that sooner or later anyhow. We live out in the country where we have our own transformer on the pole. Some years ago we replaced an old farmhouse with a new house and installed a 200 amp breaker box with "400 amp" leads to the pole. Three years later on a hot summer day, we were holding a power hammer rebuilding workshop and the power went out. I called the utility co. and they came out right away. Reset the breaker on the pole and told me "gee, you sure are pulling a lot of power. You are drawing 54 amps on one leg and 57 amps on the other!" (To which I said "Sure sounds like I have 'em well balanced.") I told 'em that 55 amps shouldn't be a problem since I have a 200 amp service that is almost new that they recently hooked up to. ----Now, HERE comes the point: They said --- 'yeh, but we never install transformers big enough to handle the max load from your main box. We always assume that you only got that big box so you'd have a lot of extra breakers!!!" So, if your utility co. used that reasoning and if they did it 20 or 30 or 40 years ago, it's quite likely that the whole neighborhood is underpowered.
By the way, they removed my old 5 or 7.5 KVA transformer and installed a 10 or 15 KVA and no troubles since.
Pete Stanaitis
snipped-for-privacy@gmail.com wrote:
Reply to
spaco
If you are pullng down a neighbor, it's the power company's problem. Best bet is to have the NEIGHBOR call the power co and ask them to install (temporarily) a line voltage recorder. Then run the mill on a series of heavy cuts. 3 minutes on, 2 minute off, etc. Nice square wave forms on the recorder will get their attention.
Keep in mind that 2 or 3 volts variation is considered 'normal' by the power co. You might want to get a good voltmeter, plug it in at the neighbor's place and see what readings you get.
snipped-for-privacy@gmail.com wrote:
Reply to
RoyJ
I looked into a VFD for my mill but decided against it. Part of the reason was expense (the spindle motor is 10hp so a VFD is lotsa $$) but the main reason was that all the information I could gather said that the VFDs didn't like to ramp up one motor and then ramp up another. My table drive motor is 3hp, so after the spindle is going I'd need to turn on/off the table drive, plus there's a light and a coolant pump. I still need to build a rotary phase converter for this machine..... this winter for sure.
al.
Reply to
Al MacDonald
It would be worth checking on the power company's policies before calling attention to yourself. Our local power company (Central Maine Power) reserves the right to refuse service to single phase motors and phase converters larger than 5HP. I've never heard of it happening, but presumably there's a reason for the provision in the tariffs - perhaps so they can avoid spending money to upgrade long rural feeds that are approaching their capacity.
Ned Simmons
Reply to
Ned Simmons
I remember one time asking about having a 3 phase line put in, its about 1/4 mile down the street where 3 phase power is. They told me about $25,000 to put it in and recommended phase converter.
Reply to
Carbonite
I was told by someone that they will put a meter on the line and check for voltage drops. I talked to a person that sells phase converters and he can't believe that I am pulling more than 100 amps from my service. We will see, I will keep on there backs for sure.
Reply to
Carbonite
Consider two VFD's or rotary converters - one sized for the spindle motor, one for the table drive motor. Better than trying to kludge it to make one VFD do both, which probably can't work anyway.
The work lights and the controls can easily be converted to a separate 120V or 120-208/240V single phase power feed - the lights are more than likely either incandescent or fluorescent. The only tricky part is integrating any automation controls on the mill with the outboard VFD's, but you can do almost anything with a little forethought.
The coolant pump is more than likely oversized for the load and can use a static converter, or you build a small rotary converter, or change the stupid pump motor out to a single-phase.
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Reply to
Bruce L. Bergman
Yipes. I'll keep that in mind for future complaints (being in Maine).
Steve
Reply to
Steve Smith
Update on my phase converter problem. I called NYSEG and they came out and said that the transformer on the pole was too small. I guess I was accually hooked up to two other houses on the same transformer. On top of that the neighbors used to have 100 amp services and upgraded to 150 amp services. Wether that made a difference or not we will see. The power company ask for my loads and ask about the neighbors service. They are putting in the new transformer and larger wire for free. I will keep my 100 amp service and they said I was within my service. Thanks everyone for responding, I will let you all know what the outcome is.
Steve
Reply to
Carbonite

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