Safety Features
Safety Features
Anti-Island Protection
A condition referred to as "Islanding" occurs when a distributed generation source (such as the PV100S Grid-tied Photovoltaic Inverter) continues to energize a portion of the utility grid after the utility experiences an interruption in service. This type of condition may compromise personnel safety, restoration of service, and equipment reliability.
The PV100S employs a method for detecting the islanding condition using a Phase-Shift-Loop (PSL). This method is implemented in the CCU2 to prevent islanding of the PV100S. The CCU2 continuously makes minor adjustments to the power factor phase angle above and below unity. In the event of a utility interruption or outage, these adjustments destabilize the feedback between the inverter and the remaining load, resulting in an over/under frequency or voltage condition.
Upon detection of such a condition, the PV100S then performs an immediate orderly shutdown and opens both the main AC and DC contactors. The fault condition will remain latched until the utility voltage and frequency have returned to normal for at least 5 minutes.
This method has been extensively tested and proven to exceed the requirements of IEEE-929 (Recommended Practices for Utility Interface of Photovoltaic [PV] Systems) and UL-1741 (Static Inverters and Converters for use in Independent Power Systems).
PV Ground Fault Detection
The PV100S is equipped with a ground fault detection circuit by means of a Hall-effect current transducer (CT3). This circuit is active when the PV array is properly grounded. In the event of a ground fault exceeding 10 amps DC, the PV100S will execute an immediate orderly shutdown, open both the main AC and DC contactors, and report a ground fault on the LCD of the UFCU. The PV100S will remain faulted until the ground fault is remedied and the advisory is cleared at the operator interface.
For additional information, see Chapter 4, “Troubleshooting”.
DC Over-voltage Detection
In the event of DC voltage greater than 600 Vdc, the PV100S will execute an orderly shutdown and will report a fault to the operator interface. If DC voltage remains greater than 600 Vdc, the PV100S may be irreparably damaged.
See Chapter 4, “Troubleshooting” for further information on this fault condition.
