ABB RELION REB500 Applications Manual

Also see for Relion REB500: Product guide Technical manual Applications manual Communication protocol manual Technical manual

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ABB RELION REB500 Applications Manual Manual pdf 39 page image

While the Switch inhibit signal is active, it is recommended to avoid operatingisolators or circuit-breakers in the station. On no account is it permitted tooperate an isolator or circuit-breaker in the bay from which the alarmoriginates. This is because the last isolator status is retained in the bus imageof busbar protection, which therefore would no longer correspond to the actualstate of the station and would falsify the intertripping system.A false differential current may result, which if the isolator alarm is notconfigured to block the protection would cause mal-operation of theprotection.The incorrect control of the intertripping logic means that in the event of afault the wrong circuit-breakers are tripped.The Switch inhibit signal is not set, however, if the isolator or circuit-breaker concerned doesnot determine the assignment of protection zones. Figure 16 shows an example for a bus-tiebreaker. Isolators Q1, Q2, Q10 and Q20 are open and therefore the bus-tie breaker Q0 is notassigned to a protection zone and of no consequence for the circuit-breaker image.Q11Q21Q2 Q1 Q20 Q10Q012000041-IEC18000264-1-en.vsdIEC18000264 V1 EN-USFigure 16: Circuit-breaker image of no consequence if the isolators are open7.2.8 Acknowledging the isolator alarm GUID-1C8C3F1D-FCF9-47AC-B2A0-4276BD59B95C v2Figure 17 shows the responses of the signals in the event of an isolator alarm and switchinhibit.The isolator alarm is reset and the blocking of the protection cancelled by applying a signal tothe input Accept bus image alarm. The signal Switch inhibit stays active.If it is not acknowledged, the signal Isolator alarm is reset and blocking cancelledautomatically should the isolators and the circuit-breakers adopt correct statuses.If the isolator alarm is set due to the failure of the auxiliary supply for the returnconfirmation circuit (for example, MCB. trip or deliberately switched off formaintenance), it may be acknowledged. Providing no switching operations areperformed on the feeder, a hazardous situation cannot arise because the laststatus is retained for busbar protection.If the isolator alarm is set due to an undefined status of the main isolatorcontact (for example, a mechanical defect), a wiring error or incorrectsimulation, station operating guidelines must specify whether the protectionshould be blocked (danger of failing to trip) or be reset (danger of mal-operation).1MRK 505 399-UEN B Section 7System SettingsDistributed busbar protection REB500 33Application manual© Copyright 2019 ABB. All rights reserved