GE Multilin L60 Line Phase Comparison System 5-3055 SETTINGS 5.8 TRANSDUCER INPUTS AND OUTPUTS5DCMA OUTPUT H1 SOURCE: “SRC 1 P”DCMA OUTPUT H1 RANGE: “–1 to 1 mA”DCMA OUTPUT H1 MIN VAL: “–1.247 pu”DCMA OUTPUT H1 MAX VAL: “1.247 pu”With the above settings, the output will represent the power with the scale of 1 mA per 20.65 MW. The worst-case error forthis application can be calculated by superimposing the following two sources of error:• ±0.5% of the full scale for the analog output module, or• ±1% of reading error for the active power at power factor of 0.9For example at the reading of 20 MW, the worst-case error is 0.01 × 20 MW + 0.207 MW = 0.407 MW.EXAMPLE: CURRENT MONITORINGThe phase A current (true RMS value) is to be monitored via the H2 current output working with the range from 4 to 20 mA.The CT ratio is 5000:5 and the maximum load current is 4200 A. The current should be monitored from 0 A upwards, allow-ing for 50% overload.The phase current with the 50% overload margin is:(EQ 5.38)The base unit for current (refer to the FlexElements section in this chapter for additional details) is:(EQ 5.39)The minimum and maximum power values to be monitored (in pu) are:(EQ 5.40)The following settings should be entered:DCMA OUTPUT H2 SOURCE: “SRC 1 Ia RMS”DCMA OUTPUT H2 RANGE: “4 to 20 mA”DCMA OUTPUT H2 MIN VAL: “0.000 pu”DCMA OUTPUT H2 MAX VAL: “1.260 pu”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• ±0.25% of reading or ±0.1% of rated (whichever is greater) for currents between 0.1 and 2.0 of nominalFor 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 MONITORINGA positive-sequence voltage on a 400 kV system measured via source 2 is to be monitored by the DCmA H3 output with arange 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 should be monitored in the range from 70% to 110% of nominal.The minimum and maximum positive-sequence voltages to be monitored are:(EQ 5.41)The base unit for voltage (refer to the FlexElements section in this chapter for additional details) is:(EQ 5.42)The minimum and maximum voltage values to be monitored (in pu) are:(EQ 5.43)The following settings should be entered:0.005± 1 1–( )–( ) 20.65 MW×× 0.207 MW±=I max 1.5 4.2 kA× 6.3 kA= =I BASE 5 kA=minimum current 0 kA5 kA------------ 0 pu, maximum current 6.3 kA5 kA----------------- 1.26 pu= == =0.005 20 4–( ) 6.3 kA××± 0.504 kA±=V min 0.7 400 kV3-------------------× 161.66 kV, V max 1.1 400 kV3-------------------× 254.03 kV= == =V BASE 0.0664 kV 6024× 400 kV= =minimum voltage 161.66 kV400 kV--------------------------- 0.404 pu, maximum voltage 254.03 kV400 kV--------------------------- 0.635 pu= == =
