8-12 C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
SETTINGS EXAMPLE CHAPTER 8: APPLICATION OF SETTINGS
8
Figure 8-12: Sample capacitor bank configuration
Based on the bank configuration, CT connections, and VTs connections, a C70 model is chosen with three CT/VT modules:
two type 8L modules (in slots F and U) and one type 8V module (in slot M) to provide following protection functionality.
• Negative-sequence instantaneous overcurrent (ANSI 50_2) to provide fast backup protection against arcing within
capacitor bank
• Phase overvoltage (ANSI 59B) to provide protection against overvoltages
• Bank overcurrent protection, phase instantaneous overcurrent (ANSI 50P), neutral instantaneous overcurrent (ANSI
50N) and phase time overcurrent (ANSI 51P) to provide protection against major faults within the capacitor bank
• Bank undervoltage (ANSI 27P) to detect loss of bus voltage and trip the bank
• Voltage differential (ANSI 87V) to detect failure of one or more capacitor elements in a given string. Three voltage
differential elements can be set for this application: one between two tap voltages (ANSI 87V-1) and two between the
bus voltage and tap voltage in both strings (ANSI 87V-2 and 87V-3).
• Phase current unbalance (ANSI 60P) to detect failure of one or more capacitor elements in a given string
8.4.2 VT and CT setup
The CT and VT connections are shown in the previous figure. The CT channels are connected as follows:
• The type 8L CT/VT module F1 to F3 three-phase CT channels are connected to the bus side three-phase CTs with a
120 / 5 A ratio
• The type 8L CT/VT module U1 to U3 three-phase CT channels are connected to the neutral side window CTs with a
50 / 5 A ratio
The following settings are applied in the EnerVista UR Setup software.
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