GE T35 UR Series, Инструкция по эксплуатации

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5-188 T35 Transformer Protection System GE Multilin
5.9 TRANSDUCER INPUTS AND OUTPUTS 5 SETTINGS
5
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.
3
0.005 1 0
–
( ) ×
254.03 kV
× ±
1.27 kV
±
=