PROTECT ION TR I P UNI TS
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Zone Selectivity The function allows multiple circuit-breakers belong- ing to the same installation to be connected to- gether, in order to coordinate the trip units and to re- duce the tripping times in the case of protections S, G, S2 and I. Thus, in the event of a failure: • the circuit-breaker closest to the fault trips • the other circuit-breakers are locked for a pro- grammable time. Each circuit-breaker that detects a fault reports it to the circuit-breaker upstream; the circuit-breaker that detects the fault but does not receive any communi- cation from those downstream opens without wait- ing for the set delay to elapse. It is possible to enable zone selectivity if a fixed-time curve has been selected and the auxiliary supply is present. StartUp Enable The function modifies the threshold of the protec- tion for a period that can be set by the user, avoid- ing unwanted trips due to high inrush currents of certain loads (motors, transformers, lamps). The starting phase lasts 100ms to 30s and is recog - nized automatically by the trip unit: • at the closing of the circuit-breaker with a self-supplied trip unit; • when the peak value of the maximum current exceeds the set threshold (0.1…10 x In) with an externally supplied trip unit. A new start-up is possible after the current falls be- low the threshold. This function can be activated with a fixed time protection function (t = k). More - over, the I3 startup threshold must be higher than the I2 startup threshold.
Protection blocks With the Ekip Connect software, six blocks are available for some protections, which is useful for deactivating the protection based on programma- ble events. In particular: • four blocks are associated with the programma- ble states A, B, C and D • one block is associated with the start-up (present for protections that have a StartUp function); • one block, not present for frequency protections, is associated with the checking of the measured frequency. Each block is independent and has its own activa- tion command. The protection is deactivated for a time equal to the duration of the event itself: • if the programmed event occurs (true), in the case of state-based blocks • if the StartUp function is active and the start-up threshold is exceeded (the active block for the set start-up time), whenever the StartUp block function is enabled. • if at least one frequency measured is outside the range 30…80 Hz, in the case of a frequency based block. Directional Zone Selectivity The Zone Selectivity function allows multiple cir- cuit-breakers belonging to the same installation to be connected together in order to coordinate the trip units and reduce tripping times, but with some important differences: • it is to be used in installations with a ring circuit • it allows tripping to be managed and coordinated according to the power flows (determined by the direction of the current), in order to minimize dis- persion of energy. It works as an alternative to S and G Zone Selectivity.
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