Liebert Series 600T installation manual Grounding Local Electrode

GROUNDING	LOCAL	LOCAL
		GROUNDING
ELECTRODE
	GROUNDING
		ELECTRODE
PER NEC 250-24
	ELECTRODE
		PER NEC 250-30
	PER NEC 250-30
GROUNDING		LOCAL
ELECTRODE		GROUNDING
PER NEC 250-24		ELECTRODE
		PER NEC 250-30

Figure 5. Preferred Grounding Configuration with Ungrounded Delta Source Input (top) and

Corner-Grounded Delta (bottom)

7.5.Grounding Configuration, 480 or 600 VAC Input and Output, Delta Source or Impedance-Grounded Wye

As previously mentioned, Series 600T UPS modules require a bypass input neutral for sensing and monitoring. With a wye-connected input source, the installer should always connect the building service neutral to the module output neutral to achieve this. When the building service is delta-connected, however, the installer must take special steps to ensure reliable UPS functioning.

If building service is ungrounded delta (and there is no intent to operate with one corner of the delta grounded, either on purpose or accidentally), the UPS requires the Series 600T Artificial Neutral Kit for proper operation. This kit uses a resistor network to create a reference point for the bypass input. In this case, the UPS output neutral must be bonded to the UPS ground. See Figure 5 above.

If the building service is corner-grounded delta or an impedance-grounded wye, the UPS requires the Series 600T Isolated Neutral Kit. This kit uses control isolation transformers to create a reference point. For this application, the UPS output neutral must not be bonded to the UPS ground.

12 Installation Manual