American Power Conversion SYMF800KH - Manual (Page 33)

Symmetra MW 800 kW 3 × 400/230 V Installation - 990-1510D 27
Specifications
Low-Impedance/High-Impedance Earthing
The Symmetra ® MW is easily integrated into either a solid grounded system, or a high-impedance
grounded system.
In a solid grounded system, the neutral power source (mains, generator, or UPS) is solidly grounded.
In the event of a down-stream ground fault, the fault current will have a path back to the source, and
the over-current device feeding the faulted part of the installation will trip and isolate the fault.
In a high-impedance grounded system, the source is grounded with an impedance (grounding
resistor). In the event of a down-stream fault, the fault current will be limited by the impedance of the
grounding resistor. The value of a high-impedance system is its ability to maintain operation with a
given system fault to ground, i.e. the over-current device will only trip at line-to-line faults or double
ground faults. For a high-impedance system to provide enhanced power system reliability and
availability, a ground-fault monitoring/alarm system is required.
Note
Grounding electrode conductor to be supplied by the customer.
For more information refer to “Appendix” in Installation Guide.