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Chapter 3
CGCM-DLR Unit Operation
62
Loss of Excitation Power (PMG) (27)
If voltage to the PMG excitation power inputs falls below 10V AC for
approximately 400 ms or more, a Loss of Excitation power fault occurs. When
single phase PMG is selected, the CGCM-DLR unit senses phases A and C for
this function. This function is disabled when Shunt excitation is selected, the
EngineIdle tag is set, or the host Logix controller is in Program mode. If this fault
occurs, tag LossPMGFlt = 1 in the Scheduled Read table.
Reverse VAR (40Q)
When the Reverse VAR level exceeds the characteristic curve for an amount of
time you set, a Reverse VAR fault occurs. The characteristic curve is a line that
begins at the pickup setting you defined at zero real power and extends toward
positive reactive power at an angle of 8°. Once the VARs increase above the
threshold, the Reverse VAR fault timer is reset. If this fault occurs, the
CGCM-DLR unit shuts down excitation and sets tag RevVARFlt = 1 in the
Scheduled Read table.
The
Reverse VAR Characteristic
Figure 35 - Reverse VAR Characteristic
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
Rockwell Automation Publication 1407-UM002B-EN-P - February 2019
graph shows more details.
Generator
Characteristic
Curve
Reverse VAR
Trip Setting
Trip Region
0.0
0.2
0.4
0.6
Real Power, per Unit
8˚
0.8
1.0
1.2
1.4
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