GE C70 Instruction Manual page 514

TRANSDUCER INPUTS/OUTPUTS
The base unit for current (see the FlexElements section in this chapter for additional details) is:
The minimum and maximum power values to be monitored (in pu) are:
The following settings are entered:
DCMA OUTPUT H2 SOURCE
DCMA OUTPUT H2 RANGE
DCMA OUTPUT H2 MIN VAL
DCMA OUTPUT H2 MAX VAL
The worst-case error for this application can be calculated by superimposing the following two sources of error:
• ±0.5% of the full scale for the analog output module, or ±0.005 x (20 - 4) x 6.3 kA = ±0.504 kA
• ±0.25% of reading or ±0.1% of rated (whichever is greater) for currents between 0.1 and 2.0 of nominal
For example, at the reading of 4.2 kA, the worst-case error is max(0.0025 × 4.2 kA, 0.001 × 5 kA) + 0.504 kA = 0.515 kA.
Example: Voltage monitoring
A positive-sequence voltage on a 400 kV system measured via source 2 is to be monitored by the DCmA H3 output with a
range of 0 to 1 mA. The VT secondary setting is 66.4 V, the VT ratio setting is 6024, and the VT connection setting is "Delta."
The voltage is to be monitored in the range from 70% to 110% of nominal.
The minimum and maximum positive-sequence voltages to be monitored are:
5
The base unit for voltage (see the FlexElements section in this chapter for additional details) is:
The minimum and maximum voltage values to be monitored (in pu) are:
The following settings are entered:
DCMA OUTPUT H3 SOURCE
DCMA OUTPUT H3 RANGE
DCMA OUTPUT H3 MIN VAL
DCMA OUTPUT H3 MAX VAL
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" (see 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 ± 0.005 x (1-0) x 254.03 kV = ±1.27 kV
• ±0.5% of reading
For example, under nominal conditions, the positive-sequence reads 230.94 kV and the worst-case error is
0.005 × 230.94 kV + 1.27 kV = 2.42 kV.
5-310
: "SRC 1 Ia RMS"
: "4 to 20 mA"
: "0.000 pu"
: "1.260 pu"
: "SRC 2 V_1 mag"
: "0 to 1 mA"
: "0.404 pu"
: "0.635 pu"
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
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CHAPTER 5: SETTINGS
Eq. 5-35
Eq. 5-36
Eq. 5-37
Eq. 5-38
Eq. 5-39