1MRS751802-MUM REX 521201Protection RelayTechnical Reference Manual, Standard Configurations11.1.2. MeasurementsFollowing measurements are supported in this application example:• True RMS measurement of phase currents• True RMS measurement of phase-to-earth voltages• True RMS measurement of residual voltage (calculated value from phase-to-earthvoltages)• Fundamental frequency active power [kW]• Fundamental frequency reactive power [kVAr]• Fundamental frequency displacement power factor cos (φ)• Power factor PF including the harmonics• Fundamental frequency active energy [kWh]• Fundamental frequency reactive energy [kvarh]• System frequency measurement11.1.3. ProtectionAll the necessary settings for the protection functions can be set via the RelaySetting Tool or the local HMI. The settings can be found inMain menu\Protection\.11.1.3.1. Overcurrent protectionThe basic overcurrent protection principles presented in the application exampleSection 11.2. Incoming feeder, High H02 are applicable, but different overcurrentprotection stages have been used.In the example of the incoming feeder application, the stage 3I>>-> of theovercurrent protection of the incoming feeder operate time-selectively as adirectional overcurrent back-up protection of the outgoing feeders. The stage 3I> ->is used for the directional overcurrent protection of the parallel incoming feeders todisconnect faulty feeder from the network. The stage 3I>>> is used for the non-directional short-circuit protection of the busbar system.11.1.3.2. Synchro-check functionIn this application example the synchro-check function is used for checking theconditions for the closing of incoming feeders circuit-breaker. The synchro-checkfunction does not allow the circuit breaker to be closed if the criteria are not fulfilled.The synchro-check function can be used for two different operating conditions. Themost typical case is the one where both sides of the circuit breaker to be closed arelive and thus the synchronism is always checked before the circuit breaker is giventhe permission to close. In the other situation one or both sides of the circuit breakerto be closed are dead and, consequently, the frequency and phase differences cannotbe measured, in which case the relay checks the energizing direction.Operation criteria of the function are:• Voltages must be in accordance with the energizing direction.
