Islanding Protection - Xantrex XW4024-120 Operation Manual

Islanding Protection

975-0240-01-01
Islanding protection is an essential safety feature that ensures no person working
on the utility grid is harmed by a distributed energy source, such an XW Inverter/
Charger. Islanding protection also prevents loads connected to the inverter from
being damaged by fluctuating utility grid input. Default software settings are
programmed into each XW Inverter/Charger at the factory to ensure it does not
"island" according to applicable safety regulations (such as IEEE 1547 and UL
1741).
As well, the XW Inverter/Charger uses a proprietary positive feedback controller
that has minimal effect on total harmonic distortion, and is guaranteed to detect
islanding conditions for all power levels, as governed by IEEE and UL standards.
In some instances it may be desirable from both a utility and customer point of
view to adjust default anti-islanding settings. For example, the XW Inverter/
Charger may experience "nuisance trips" if the grid is weak and the voltage falls
outside the allowable range specified in the regulations. It may be difficult for a
utility to upgrade the grid to eliminate this problem. With permission from the
utility, the factory settings may be changed to allow the XW Inverter/Charger to
operate over a wider grid voltage range.
These settings should only be changed by qualified service personnel, using a
special software application provided by Xantrex. Changing any values may
compromise compliance with safety regulations. Do not do so without first
consulting with the utility and agreeing on acceptable settings.
While selling power, the XW Inverter/Charger continuously monitors utility grid
voltage and frequency. If the grid voltage and frequency move beyond the XW
Inverter/Charger default ranges
the XW Inverter/Charger stops selling power to AC1 and disconnects from the
utility grid for five minutes (Five minutes is the minimum reconnect time, and is
not adjustable.) If the utility grid voltage and frequency have returned to their
nominal values when the reconnect time has expired, the XW Inverter/Charger
begins selling power again.
The Fault light on the XW Inverter/Charger information panel indicates that a
utility fault has occurred. No fault code appears on the three-character display
because the fault is with the utility grid, not the XW Inverter/Charger.
The XW System Control Panel indicates a utility fault with the Fault light and a
fault message on its screen (faults F23 to F40 are utility faults—see Table 4-5 on
page 4–18). The fault cannot be manually cleared. Utility faults clear
automatically when the utility grid voltage and frequency return to their nominal
values.
1.See "Electrical Specifications" on page A–2.
1
—during a power surge or outage, for example—
Basic Operation
1–5