Installation manual

Introduction
1–2 153396 Revision D
This manual is for use by qualified installers only
Description of the Xantrex GT250
The Xantrex GT250 Grid-Tied Photovoltaic Inverter is a utility interactive,
three-phase power conversion system for grid-connected photovoltaic arrays with a
power rating of 250 kW. Designed to be easy to install and operate, the Xantrex
GT250 automates start-up, shutdown, and fault detection scenarios. With
user-definable power tracking that matches the inverter to the array and adjustable
delay periods, users are able to customize startup and shutdown sequences.
Multiple Xantrex GT250 inverters are easily paralleled for larger power installations.
Power Conversion System
The Xantrex GT250 power conversion system consists of a pulse-width modulated
(PWM) inverter, switch gear for isolation and protection of the connected AC and
DC power sources. Housed in a rugged NEMA 3R rated, corrosive resistant,
powder-coated steel enclosure, the Xantrex GT250 incorporates sophisticated
Insulated Gate Bipolar Transistors (IGBTs) as the main power switching devices. An
advanced, field-proven, Maximum Peak Power Tracker (MPPT) integrated within the
Xantrex GT250 control firmware ensures the optimum power throughput for
harvesting energy from the photovoltaic array.
Advanced Design Features
The advanced design of the Xantrex GT250 includes an EMI output filter and the
main AC contactor located electrically on the utility side of the isolation
transformer to prevent transformer tare losses when the unit is not operating.
The Xantrex GT250 also includes an inrush limit assembly to prevent nuisance
utility circuit breaker trips when the isolation transformer is energized.
A sophisticated control scheme optimizes the operation of the Xantrex GT250
cooling fans as needed for increased overall system efficiency.
Additionally, the Xantrex GT250 integrated controller contains self-protection
features including over and under voltage and frequency safeguards in
compliance with UL1741 2nd Edition.
Anti-islanding An integral anti-islanding protection scheme prevents the inverter from feeding
power to the grid in the event of a utility outage.
Auto-Phase
Rotation
The Xantrex GT250 includes the ability to auto-sense and correct for a
“mis-phased” connection at the AC interface terminals. In the event the power
conductors from the utility are not phased correctly at the AC interface terminals,
the Xantrex GT250 will sense the discrepancy and automatically correct for a
clockwise (A-B-C) phase rotation.
Local Display and
Remote Graphic
User Interface
The Xantrex GT250 includes a local user interface comprised of an O
N/OFF
switch, keypad, and 4-line, 80 character VFD display.
A user-friendly Xantrex GT View Graphic User Interface (GUI) provides a remote
interface for operator interrogation of Xantrex GT250 system status, control,
metering/data logging and protective functions within the Xantrex GT250. The
status, control, and logging features are supported by an optional modem via an
RS232 connection for remote monitoring. Alternatively, a user selectable RS485/
Modbus connection is also available for remote plant monitoring.