GE C70 Instruction Manual

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Contents

8-16 C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUALSETTINGS EXAMPLE CHAPTER 8: APPLICATION OF SETTINGS8Table 8-1: Unbalance values for maximum system conditionsTo check the limits of protection sensitivity, the same calculations are repeated for the minimum system conditions, whichare considered to be 0.85 pu of nominal system voltage.The minimum line to neutral system voltage is:Eq. 8-22The following table summarizes the unbalance values during minimum system conditions.Table 8-2: Unbalance values for minimum system conditionsThe balance values during minimum operating conditions can be used to check sensitivity.8.4.5 Bank voltage differential settingsThe bank configuration, CT location, and VT locations allow applying three voltage differential elements:• An 87V-1 differential element measuring the differential voltage between the two bottom taps• An 87V-2 differential element measuring the differential voltage between the upper capacitor string and bottomcapacitor can for string 1• An 87V-3 differential element measuring the differential voltage between the upper capacitor string and bottomcapacitor can for string 20 1894.42 Ω 1894.42 Ω 175.37 V 175.37 V 81340.00 V 1.000 pu 0.0000 pu 0.0000 pu 0.0000 pu1 1894.42 Ω 1849.41 Ω 175.37 V 179.64 V 81335.73 V 1.024 pu 0.0249 pu 0.0249 pu 0.0209 pu2 1894.42 Ω 1804.40 Ω 175.37 V 184.12 V 81331.25 V 1.050 pu 0.0510 pu 0.0510 pu 0.0429 pu3 1894.42 Ω 1759.39 Ω 175.37 V 188.83 V 81326.54 V 1.077 pu 0.0785 pu 0.0785 pu 0.0660 pu4 1894.42 Ω 1714.38 Ω 175.37 V 193.79 V 81321.58 V 1.105 pu 0.1074 pu 0.1074 pu 0.0904 pu5 1894.42 Ω 1669.38 Ω 175.37 V 199.01 V 81316.36 V 1.135 pu 0.1379 pu 0.1379 pu 0.1160 pu6 1894.42 Ω 1624.37 Ω 175.37 V 204.52 V 81310.85 V 1.167 pu 0.1701 pu 0.1701 pu 0.1431 pu7 1894.42 Ω 1579.36 Ω 175.37 V 210.35 V 81305.02 V 1.200 pu 0.2041 pu 0.2041 pu 0.1717 pu8 1894.42 Ω 1534.35 Ω 175.37 V 216.52 V 81298.85 V 1.235 pu 0.2401 pu 0.2401 pu 0.2020 pu9 1894.42 Ω 1489.34 Ω 175.37 V 223.07 V 81292.30 V 1.273 pu 0.2783 pu 0.2783 pu 0.2341 pu10 1894.42 Ω 1444.34 Ω 175.37 V 230.02 V 81285.35 V 1.313 pu 0.3188 pu 0.3188 pu 0.2682 pu0 1894.42 Ω 1894.42 Ω 145.70 V 145.70 V 67577.30 V 1.000 pu 0.0000 pu 0.0000 pu 0.0000 pu1 1894.42 Ω 1849.41 Ω 145.70 V 149.24 V 67573.76 V 1.024 pu 0.0207 pu 0.0207 pu 0.0174 pu2 1894.42 Ω 1804.40 Ω 145.70 V 152.97 V 67570.03 V 1.050 pu 0.0424 pu 0.0424 pu 0.0357 pu3 1894.42 Ω 1759.39 Ω 145.70 V 156.88 V 67566.12 V 1.077 pu 0.0652 pu 0.0652 pu 0.0549 pu4 1894.42 Ω 1714.38 Ω 145.70 V 161.00 V 67562.00 V 1.105 pu 0.0893 pu 0.0893 pu 0.0751 pu5 1894.42 Ω 1669.38 Ω 145.70 V 165.34 V 67557.66 V 1.135 pu 0.1146 pu 0.1146 pu 0.0964 pu6 1894.42 Ω 1624.37 Ω 145.70 V 169.92 V 67553.08 V 1.167 pu 0.1413 pu 0.1413 pu 0.1189 pu7 1894.42 Ω 1579.36 Ω 145.70 V 174.76 V 67548.24 V 1.200 pu 0.1696 pu 0.1696 pu 0.1426 pu8 1894.42 Ω 1534.35 Ω 145.70 V 179.89 V 67543.11 V 1.235 pu 0.1995 pu 0.1995 pu 0.1678 pu9 1894.42 Ω 1489.34 Ω 145.70 V 185.32 V 67537.68 V 1.273 pu 0.2312 pu 0.2312 pu 0.1945 pu10 1894.42 Ω 1444.34 Ω 145.70 V 191.10 V 67531.90 V 1.313 pu 0.2649 pu 0.2649 pu 0.2228 pun f Z Cs Z Csf V tap1 V tap2 V top OV V diff tap( ) V diff string( ) I unbalV min0.85 V nom×3--------------------------- 0.85 138000 V×3-------------------------------------- 67723 V= = =n f Z Cs Z Csf V tap1 V tap2 V top OV V diff tap( ) V diff string( ) I unbal