GE Multilin g60

GE Multilin G60 Generator Protection System 5-275
5 SETTINGS 5.9 TRANSDUCER INPUTS AND OUTPUTS
5
(EQ 5.63)
The minimum and maximum voltage values to be monitored (in pu) are:
(EQ 5.64)
The following settings should be entered:
DCMA OUTPUT H3 SOURCE: “SRC 2 V_1 mag”
DCMA OUTPUT H3 RANGE: “0 to 1 mA”
DCMA OUTPUT H3 MIN VAL: “0.404 pu”
DCMA OUTPUT H3 MAX VAL: “0.635 pu”
The limit settings differ from the expected 0.7 pu and 1.1 pu because the relay calculates the positive-sequence quantities
scaled to the phase-to-ground voltages, even if the VTs are connected in “Delta” (refer to the Metering conventions section
in chapter 6), while at the same time the VT nominal voltage is 1 pu for the settings. Consequently the settings required in
this example differ from naturally expected by the factor of .
The worst-case error for this application could be calculated by superimposing the following two sources of error:
• ±0.5% of the full scale for the analog output module, or
• ±0.5% of reading
For example, under nominal conditions, the positive-sequence reads 230.94 kV and the worst-case error is
0.005 x 230.94 kV + 1.27 kV = 2.42 kV.
V
BASE
0.0664 kV 6024 400 kV==
minimum voltage
161.66 kV
400 kV
--------------------------- 0.404 pu, maximum voltage
254.03 kV
400 kV
--------------------------- 0.635 pu====
3
0.005 1 0– 254.03 kV 1.27 kV=