Current circuit supervision CCSSPVC compares the residual current from a three-phase set of current transformer cores with the neutral point current on a separateinput taken from another set of cores on the same current transformer.IMinOp: It must be set as a minimum to twice the residual current in the supervisedCT circuits under normal service conditions and rated primary current.Ip>Block: It is normally set at 150% to block the function during transientconditions.The FAIL output is connected to the blocking input of the protection function to beblocked at faulty CT secondary circuits.7.2 Fuse failure supervision FUFSPVC IP14556-1 v37.2.1 IdentificationM14869-1 v4Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberFuse failure supervision FUFSPVC - -7.2.2 Application SEMOD113803-4 v10Different protection functions within the protection IED, operates on the basis ofthe measured voltage in the relay point. Examples are:• impedance protection functions• undervoltage function• energizing check function and voltage check for the weak infeed logicThese functions can operate unintentionally if a fault occurs in the secondarycircuits between the voltage instrument transformers and the IED.It is possible to use different measures to prevent such unwanted operations.Miniature circuit breakers in the voltage measuring circuits should be located asclose as possible to the voltage instrument transformers, and shall be equipped withauxiliary contacts that are wired to the IEDs. Separate fuse-failure monitoring IEDsor elements within the protection and monitoring devices are another possibilities.These solutions are combined to get the best possible effect in the fuse failuresupervision function (FUFSPVC).FUFSPVC function built into the IED products can operate on the basis of externalbinary signals from the miniature circuit breaker or from the line disconnector. TheSection 7 1MRK 511 423-UEN ASecondary system supervision90 Bay control REC650 2.2 IECApplication manual
