Xantrex Technology PV225S-480-P - Manual (Page 25)

System Specifications
152606 1–5
System Ground Requirements
This product is intended to be installed as part of a permanently grounded
electrical system per the National Electric Code ANSI/NFPA 70. A copper ground
rod must be installed within three feet of the PV225S enclosures and connected to
the unit as described in “System Grounding” on page 3–12. The single-point
ground for the system is to be made at the AC ground bus bar (TB12) in the AC
Interface Enclosure.
System Neutral Requirements
The PV225S is designed to be installed as a 4-wire system. As required by the
UL 1741 listing, a neutral conductor from the utility-interconnect must be
terminated at TB11 within the AC Interface Enclosure to ensure that the AC
voltage sensing circuit can perform an individual phase voltage (line-to-neutral)
measurement. The function of the neutral connection is to provide a point of
reference for measurement purposes that is essentially at ground potential. No
power will flow through the neutral conductor.
Utility Side Isolation Transformer Requirements
The PV225S is supplied with a high-efficiency custom Wye:Wye, isolation
transformer as part of the AC Interface/Transformer assembly. The utility side
windings of the isolation transformer are configured Wye and must match the
voltage at the utility inter-tie. The PV225S is a balanced, three-phase,
current-sourcing inverter and only operates with the presence of a stable utility
voltage. The transformer is also supplied with a neutral connection on the utility
interconnect. Connection of this utility-side neutral does not affect the operation
of the inverter, however connection of the neutral on the inverter-side does affect
the operation and must be left floating or disconnected. Single-phase, grounded
loads which may be present between the transformer and utility, will maintain
their existing ground reference at the utility distribution transformer.
CAUTION: Equipment Damage
If the Isolation Transformer (T6-X0) neutral terminal is tied to ground, it will cause
irreparable damage to the PV225S. Check local regulations for their requirements
regarding the connection of the neutral.
WARNING: Lethal Voltage
Grounding the neutral of a Wye-wound transformer may create an “open delta” condition,
depending on the utility configuration. This condition may keep the PV225S from
detecting a loss of phase condition on the utility system, which may allow potentially
lethal voltage to be present on the open-phase wiring.