• Voltage in excess of the nameplate rating at fundamental frequency, but not over 110%of rated RMS voltage• Harmonic voltages superimposed on the fundamental frequency• Reactive power manufacturing tolerance of up to 115% of rated reactive power5. Capacitor units rated above 600 V shall have an internal discharge device to reduce theresidual voltage to 50 V or less in 5 or 10 minutes (depending on national standard).Note that capacitor units designed for special applications can exceed these ratings.Thus, as a general rule, the minimum number of capacitor units connected in parallel within a SCBis such that isolation of one capacitor unit in a group should not cause a voltage unbalancesufficient to place more than 110% of rated voltage on the remaining capacitors of that parallelgroup. Equally, the minimum number of series connected groups within a SCB is such thatcomplete bypass of one group should not pause voltage higher than 110% of the rated voltage onthe remaining capacitors of that serial group. The value of 110% is the maximum continuousovervoltage capability of capacitor units as per IEEE Std 18-1992.The SCB typically requires the following types of IED protection:1. Short circuit protection for SCB and connecting leads (can be provided by using PHPIOC,OC4PTOC, CVGAPC, T2WPDIF/T3WPDIF or HZPDIF functions)2. Ground-fault protection for SCB and connecting leads (can be provided by using EFPIOC,EF4PTOC, CVGAPC, T2WPDIF/T3WPDIF or HZPDIF functions)3. Current or Voltage based unbalance protection for SCB (can be provided by using EF4PTOC,OC4PTOC, CVGAPC or VDCPTOV functions)4. Overload protection for SCB5. Undercurrent protection for SCB6. Reconnection inhibit protection for SCB7. Restrike condition detectionCBPGAPC function can be used to provide the last four types of protection mentioned in the abovelist.7.16.3 Setting guidelines GUID-CECD6525-779C-4A77-844D-031AAEE3A5B6 v1GUID-7C456976-BA0D-4AAC-9C7A-F73AF52B2B44 v2This setting example will be done for application as shown in figure 90:1MRK 511 358-UUS A Section 7Current protection193Application manual
