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Old December 11th, 2002, 02:06 AM   #13
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rogerhollingsworth is offline
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Join Date: Nov 2002
Location: Southern Ohio.
Posts: 385


Drewcrew6 is correct, that is not a good situation, follow up before someone gets hurt.

I believe in separation and isolation, I do not agree with grounding one side of a control transformer and the situation with Awalinski is case and point.
I like to layout the circuitry visually and physically separated with separate grounds for AC and DC. As I once read, compare your control system to your body, if you put bad food in you are going to get sick. The same goes with your control circuit.

When designing your control system you should know what your power source is, starting at the high voltage substation and follow that grounding/power scheme through out.

(going back in time)
Tying the Negative leg of the DC power supply to ground is not a good idea, it compromises the isolation between the AC and regulated DC.
All DC power supplies offer a plus (+) and minus (-) output connection that is isolated from the AC input.
The AC ground should in no way be connected to either the positive or negative connection of the 24VDC power supply.
Harmonic current flow in the ground wire is a good reason to keep the AC input separate and isolated from the DC output.

Noise does not necessarily need to be directed to ground, merely returned to its source.

This is strictly my opinion which is subject to change without notice.
(only small stones please)
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