CPS SCA50KTL-DO/US-480, Installation And Operation Manual

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2.6. Anti-islanding Detection
The SCA50KTL-DO/US-480 and SCA60KTL-DO/US-480 inverters include
Unintentional Islanding detection as required by UL 1741/IEEE 1547. The
inverter will continuously make bi-directional perturbations to the frequency of
the output current by injecting a small amount of reactive power to detect a
possible islanding condition. If the grid is stable, these small perturbations will
have negligible effects on the system voltage frequency. However, in an
islanded condition the changes in reactive power will force the frequency of the
system voltage to deviate significantly, which will trigger the inverter to cease
operation and disconnect from the grid.
2.7. DC Ground Fault Protection
The inverters include residual current detection GFCI as part of the DC ground
fault detection method required by UL 1741. If there is a ground fault in the PV
array, the ground fault detection circuitry will detect leakage current, trigger an
alarm, and the inverter will cease operation. See Chapter 5 for further
information regarding GFCI Static and Dynamic trip thresholds and operation.
2.8. Surge Suppression
Standard Waveform Peak Values
Surge Category Ring Wave Combination Wave
B 6kV/0.5kA 6kV/3kA

"
Standard 1.2/50 μs - 8/20 us Combination Wave"

"Standar
d 0.5 μs - 100 kHz Ring Wave"
2.9. DC Arc-fault Protection
The inverters include DC Arc-fault detection compliant with UL 1699B. The
inverter will detect electrical noise that is indicative of a DC series arc. Upon
detection of an arc-fault, the inverter will cease operation.