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3 phase power


Jerry Kohlenstein

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I would like to run one of my controllers powered from a sepporate building on my property, but it has 3 phase power.
Just courious if this is possible or will I have problems? It would be running off one 120 volt leg.
Thanks,
Jerry

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Jerry,

If you are using a single input power cord that should not be a problem on a 3 phase power system. 3 phase power systems cause an issue when you have 2 input power cords and they are plugged into 2 different circuits that are fed off 2 different busses from each other. Mainly because the right side of the board is what has the sense circuit for the crossing fo the sine wave. In a 3 phase system the phases are 120 degrees out from one another. Where as in like a home system the 2 phases are essentially 180 out.

Hope I did not confuse you. But wanted to give you some background/reasoning for what could happen.

Chuck

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Thanks Chuck,
I am aware of the 180/120 phase angle and plan to run off a 30 amp/120volt circuit. My concern is with the RS485 control signal that will be running from the farthest out controller at my house (120/240 single phase), will that cause any problem in the signal?

Jerry

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The only time you have a problem is if the voltage from one box to another is more then 5 volts or so unbalanced on the RS485. If you have a problem PM me and I can loan you a LOR RS485 isolator, I have three I'm not using. James

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And that is not a three phase issue per se. It may easily not be an issue in your case, or it could be an issue on a large single phase 120/240 system.

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When you use different power sources with LOR's (two or more transformers) you can find a difference in voltages on the RS485 communications line greater than 5 volts. Dan did a big job a few years ago and found this voltage difference caused a massive problem with the RS485 communications. The fix is one or both of these, going wireless on the RS485 (I know a few big shows who use this idea) or LOR has built/sales an RS485 isolator. The best thing is to not fear, build it and if it does not work get with LOR for a fix and/or PM me and I can loan you an isolator.

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Thanks James,
I won't know until I setup and try in mid November. Normally both services run around 122 volts (hot to neutral). Would it make any difference which of the three legs I am on? Will I damage one or more of my controllers by testing this setup or will it just not work?

Thanks again,
Jerry

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I run on all three legs. One part of my display is mostly b and c leg and the biggest part is all three. I also run three networks with 42 controllers. The voltage difference is on the RS485 not the line voltage.

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Just keep both input legs of each individual controller on the same leg. The most likely situation from ground separation is that it won't work. And if all your power is from the same three phase circuit, the only ground separation you should get would be from faulty wiring, with power leaking down the grounds. The only part of the controller that is at risk is the 8 pin com chip that is in a socket. Our city park show runs on two separate utility feeds. About half the lights run on a feed where they are the only thing powered by the transformer, an we have had no issues to date, and have made no provisions for isolation.

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