It (Ungrounded) Systems; Supply Voltage; Connecting The Power Cables - ABB DCS880 series Hardware Manual

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IT (ungrounded) systems

Don't use EMC filters in IT systems.
The screen winding of existing dedicated transformers must be grounded.
For installation without low voltage switch (e.g. contactor, air-circuit-breaker) use an
overvoltage protection on the secondary side of the mains transformer.
The voltage shift of the isolated supply must not be larger than the voltage shift in
case on an earth fault.

Supply voltage

Check supply voltages of:
Auxiliary voltage
Cooling fan
Mains voltage for field circuit
Mains voltage for armature circuit

Connecting the power cables

Check:
Grounding and screening of power cables see manual
Cross sectional areas and tightening torques of power cable see chapter
Cross-sectional areas - Tightening torques.
Electrical installation
Voltage shift in
V
case of earth fault
SA_550_003_netzanschl_a.ai
3ADW000462R0101 DCS880 Hardware Manual e a
U1
V1
W1
Earth fault
XAUX (X99) on SDCS-PIN-H01 /
SDCS-POW-H01
Terminals
U1, V1, W1 (if used)
U1, V1, W1
Technical Guide.