Section 10 Secondary system supervision10.1 Current circuit supervision CCSSPVC IP14555-1 v510.1.1 IdentificationM14870-1 v5Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberCurrent circuit supervision CCSSPVC - 8710.1.2 Application M12395-13 v9Open or short circuited current transformer cores can cause unwanted operation ofmany protection functions such as differential, earth-fault current and negative-sequence current functions. When currents from two independent three-phase setsof CTs, or CT cores, measuring the same primary currents are available, reliablecurrent circuit supervision can be arranged by comparing the currents from the twosets. If an error in any CT circuit is detected, the protection functions concernedcan be blocked and an alarm given.In case of large currents, unequal transient saturation of CT cores with differentremanence or different saturation factor may result in differences in the secondarycurrents from the two CT sets. Unwanted blocking of protection functions duringthe transient stage must then be avoided.Current circuit supervision CCSSPVC must be sensitive and have short operatetime in order to prevent unwanted tripping from fast-acting, sensitive numericalprotections in case of faulty CT secondary circuits.Open CT circuits creates extremely high voltages in the circuitswhich is extremely dangerous for the personnel. It can also damagethe insulation and cause new problems. The application shall, thus,be done with this in consideration, especially if the protectionfunctions are blocked.10.1.3 Setting guidelines M12397-17 v8GlobalBaseSel: Selects the global base value group used by the function to defineIBase, UBase and SBase as applicable.1MRK 504 169-UEN A Section 10Secondary system supervisionTransformer protection RET650 2.2 IEC 169Application manual
