Deif CGC 400 Reference Book page 94

CGC 400 DRH 4189340786 UK
Phase-neutral
U
U
L3-L1
L1-N
U
L2-L3
As indicated in the vector diagram, there is a difference in voltage values at an error situation for the phase-
neutral voltage and the phase-phase voltage.
The table shows the actual measurements at a 10% undervoltage situation in a 400/230 volt system.
Nominal voltage
Voltage, 10% error
The alarm will occur at two different voltage levels, even though the alarm setpoint is 10% in both cases.
Example
The below 400V AC system shows that the phase-neutral voltage must change 20%, when the phase-phase
voltage changes 40 volts (10%).
Example:
U = 400/230V AC
NOM
Error situation:
U = 360V AC
L1L2
U = 360V AC
L3L1
U = 185V AC
L1-N
ΔU = 20%
PH-N
Both the generator protections and the busbar/mains protections use phase-phase voltage.
DEIF A/S
U
L1-L2
400/230
380/207
U
Phase-phase
U
U
U
L3-L1
L1-N
U
L2-L3
Phase-neutral
20%
U
L3-L1 L1-L2
U
L1-N
U
L2-L3
Protections
L1-L2
Phase-phase
400/230
360/185
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