12 Installation Manual
Figure 5. Preferred Grounding Configuration with Ungrounded Delta Source Input (top) and
Corner-Grounded Delta (bottom)
GROUNDING
ELECTRODE
PER NEC 250-24
GROUNDING
ELECTRODE
PER NEC 250-24
LOCAL
GROUNDING
ELECTRODE
PER NEC 250-30
LOCAL
GROUNDING
ELECTRODE
PER NEC 250-30
LOCAL
GROUNDING
ELECTRODE
PER NEC 250-3
0
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 a ccidentally), 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 neutra l must be
bonded to the UPS ground. See Figure 5 a bove.
If the building service is corner-grounded delta or
an impedance-grounded wye, the UPS require s 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.