DOCUMENT: 151811
SECTION 2SAFETY PV-225208 Photovoltaic Inverter
Operation and Maintenance Manual
Copyright 2003, Xantrex Technology Inc.
2-2
The terminals of the PV input may be energized if the arrays are energized. In
addition, allow 5 minutes for all capacitors within the main enclosure to discharge
after disconnecting the PV-225208 from AC and DC sources.
WARNING
ISOLATION PROCEDURE
The following procedure should be followed to de-energize the PV-225208 for maintenance:
Anti Island Protection
A digital phase-shift-loop (PSL) circuit is implemented in the DSP inverter controller to prevent
“Islanding” of the PV-225208.
The DSP continuously makes minor adjustments to the power factor phase angle above and below
unity. In the event of a utility outage, these adjustments destabilize the feedback between the inverter
and the remaining load, resulting in an over/under frequency or voltage condition. The PV-225208 then
performs an orderly shutdown. The fault condition will remain until the utility voltage and frequency have
returned to normal for 5 minutes.
This method has been extensively tested and proven to exceed the requirements of UL 1741.
1. Turn the on/off switch to the off position.
2. Open the DC interface (PV array) disconnect switch.
3. Open the AC interface disconnect switch.
4. Open the isolation transformer circuit breaker.
5. Install lockout devices on the isolation transformer circuit breaker and PV disconnect switch.
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Over/Under Voltage and Frequency
The over/under frequency and voltage detection setpoints have been chosen to be in compliance with
IEEE-929 and UL1741.