I am looking down the road at eventually getting some electrical infrastructure put in for using scenic automation. Mainly deck winches to track stuff on and off stage. Would it be advised to spec 30amp 3 phase drops in a delta configuration or would it be a better idea to spec a power drop in a Y configuration. Mainly looking at not being limited to using certain motors or VFD.
Motor Question
- Thread starter chawalang
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- Nov 24, 2005
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- Saratoga Springs, NY
Anything entertainment control focused will be Y. Most drive cabinets use an L21-30 or L15-30. Personally I'd do a cam disconnect and go from there.
If your device is designed for a delta configuration, it can be connected to a Y supply simply by not using the neutral connection. If it's a Y device with a delta supply, you need a transformer or something similar, which is much, much more cumbersome and expensive.
Edit: That is, of course, assuming the voltages are a correct match. If you need a different voltage, then you obviously would require a transformer or something similar in either case....
Edit: That is, of course, assuming the voltages are a correct match. If you need a different voltage, then you obviously would require a transformer or something similar in either case....
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- Joined
- Jun 12, 2004
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- Waterdown, ON, CA
@Footer On your side of the walls, what voltage would you supply? Up here on my side 120 / 208 is a common 3 phase Y with 347 / 600 being our next common voltage. The last decent size venue I worked on had an idler pit in their first or second basement. In the pit, the electrical PEng's spec'd a row of 277 / 480 volt Delta sources for future winches. I believe 277 / 480 is more common on your side of the walls. What voltage(s) would you suggest in Donald's world??
(I wonder if Tariff's apply?)
Toodleoo!
Ron Hebbard
bobgaggle
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- Nov 19, 2007
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- Philadelphia, PA
I always want to learn things. I thought the configuration happened at the motor, not at the supply. Supply is either Y or delta as well?
From what bobgaggle said that would make sense. It would be a better idea to speck the power drops as 30amp Y, if the motor just has three phases and a ground then the neutral wouldn't matter at that point. It would be a balanced load running at 208v that just has the Hz changed in the VFD. In that kind of situation I could get an L21-30 male to L-15-30 female adapter.
Something like this,
https://www.lockingpowercords.com/products/2850-l21-30p-to-l15-30r-adapter.aspx
Something like this,
https://www.lockingpowercords.com/products/2850-l21-30p-to-l15-30r-adapter.aspx
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- Jun 12, 2004
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- Waterdown, ON, CA
@bobgaggle Robert; how motor windings are interconnected MAY permit safe operation at one or two different voltages drawing different currents depending upon the operating voltage selected. Many / most motors may have their direction of rotation reversed. As a general rule: Single phase motors are single phase and 3 phase motors are three phase. There are a great many variations between AC motors. (before you even get into types of DC motors.)
Thinking back to my grade 12 AC motors classes: Parallel connected, series connected, induction start / repulsion run, to name three that come to mind.
EDIT: Inadvertently omitted the word "most". (Whip me! Beat me!! Make me write bad checks!!!)
Toodleoo!
Ron Hebbard
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A three phase supply is either Y or delta, yes, and that is independent of whether a connected motor is wired for star (Y) or delta connection; the latter largely is a matter of matching whatever the supply voltage happens to be. In either motor configuration, there is no need to connect the neutral of a Y supply. For most general theater systems, and in particular for theatrical lighting, the Y supply configuration is practically universal (120/208V in North America).
(There is also high-leg delta, where one of the three delta-connected transformer windings is center tapped for a neutral, in order to have a split phase and a three phase supply simultaneously. That oddball configuration is probably best ignored for this discussion!)
bobgaggle
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I'm curious about all this because our roll bender went down and me and my boss finally got it to run. Had to replace the motor, which was a 3 phase motor. But the machine control was all 230v single phase. That was confusing until we figured out the manufacturer tricked the motor by "adding" a phase with a capacitor. Then we realized that for whatever reason the new motor we bought had high/low voltage options (the old one didn't), which somehow kept the capacitor from working right. Idk, wish I knew more. Fortunately we have a 3 phase outlet so we just swapped the connector and luckily the control box had accomodations for a third leg of power, so we added some wires and now its up and running as straight 3 phase...
bobgaggle
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How do you know whats coming out of the wall? Will it be the number of conductors that gives it away? If there's no white wire is delta, that kind of thing?
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- Waterdown, ON, CA
@bobgaggle Mr. Gaggle Sir! Up here in Canada, it's not uncommon for three phase 600 volt motors to have 120 volt control and pilot lights. On your side of the walls I believe you jump from 120 / 208 to 277 / 480. Up here on my side of Donald's walls we see comparatively little 277 / 480. 120 / 208 is very common with larger horsepower motors commonly being 347 / 600 which I believe is essentially unheard of on your side of the walls. 600 is pretty nasty if / when it bites you, 347 bites bad enough. Occasionally we'll have 600 volt motors with 347 or 600 volt control but their usually installed in conduit and WELL labelled. Tiny transformers often stepped control voltage down to 120 or 240 for incandescent pilot lights.
"How do you know whats coming out of the wall? Will it be the number of conductors that gives it away?? If there's no white wire is delta, that kind of thing?"
Basically yes, that plus a good meter and the experience to know what you're expecting to read and why.
Toodleoo!
Ron Hebbard
As Ron said, basically yes. If you have three phases plus neutral plus ground, it's a Y source; if you have three phases plus ground, it's a delta system (or a Y system without the neutral being brought out to your connection, which from your point of view is equivalent to and interchangeable with a delta system). There's also the option of asking someone with local knowledge what you're dealing with. It is always wise to check the voltages on an unknown system for sanity, in any case, lest you get caught by something like a high-leg delta or mislabeled/misconnected connectors or myriad other potentially problematic things.
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- Lititz, PA
Ultimately, it comes down to what you thing you are going to need to run. It is possible to run some pretty decent sized machines on 120/208 with 30A service. We certainly build a lot of machines in that class. However if you need to move heavy things or accelerate fast (or both) you may need more current. If you really want to be prepared for anything, I would (as has been suggested) put some large service cam disconnects in good places. If you could get 200A service on each side of the stage, you can always get a PD and breakout to machines.
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- Waterdown, ON, CA
@icewolf08 200 Amps three phase at what voltage on your side of the walls? 120/208?? 277/480??? Or????
Toodleoo!
Ron Hebbard
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In the US, 120/208. Much more useful for other things besides motors, like moving lights or portable dimmers.
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It seems to me it would be better to start with what service voltages are already in the building. It would cost a small fortune to bring in a new service or install transformers just to serve some winches. That might make sense to do if the building only has single phase, but that's a different discussion. By far, the most common service in large buildings is 120/208 Wye. Really big buildings, or those will big motor loads, may have 277/480 wye. 240 delta is less common. There are buildings with multiple service voltages, too.
The nameplate voltage on a motor typically has a tolerance of +/- 10%. For example, some motors are marked 230 V, even though that isn't a standard service voltage. That is the manufacturer's way of saying the motor will operate on 207-253 V. Allowances may need to be made on the starting torque with lower voltage. 220 is also common for 198-242 V.
I believe that the winch manufacturers can supply their products for any common , three phase voltage. It isn't that big of a deal to drop the correct motor on the unit and wire the controls appropriately. I suspect single phase winches are harder to buy.
The nameplate voltage on a motor typically has a tolerance of +/- 10%. For example, some motors are marked 230 V, even though that isn't a standard service voltage. That is the manufacturer's way of saying the motor will operate on 207-253 V. Allowances may need to be made on the starting torque with lower voltage. 220 is also common for 198-242 V.
I believe that the winch manufacturers can supply their products for any common , three phase voltage. It isn't that big of a deal to drop the correct motor on the unit and wire the controls appropriately. I suspect single phase winches are harder to buy.
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