ABB RELION 630 Series Applications Manual

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Contents

ABB RELION 630 Series Applications Manual Manual pdf 40 page image

3.2.6.5 Voltage-dependent overcurrent protection PHPVOCTwo instances of voltage-dependent overcurrent function are used for protectinggenerators against overcurrent and short-circuit conditions. The function operateswhen the current exceeds a limit which is dynamically calculated based on themeasured terminal voltage.The operating characteristics can be selected to be either inverse-definite minimumtime or definite-time characteristic. The set of three phase current and voltages, I3Pand U3P, are connected to the inputs.A common operate and start signal from the both voltage-dependent overcurrentfunctions is connected to an OR-gate to form a combined operate and start signal,which provides a LED indication on the LHMI. Also a separate start and operatesignal from the both voltage-dependent overcurrent functions is connected to thedisturbance recorder.The voltage-dependent overcurrent function is blocked on detection of fuse failure.3.2.6.6 Directional earth-fault protection DEFxPDEFThe directional earth-fault protection functions are used for directional and non-directional earth-fault protection with DT or IDMT characteristic when appropriate.The configuration includes the high and low variants of the directional earth-faultprotection function. The configuration is developed considering that the core balanceCT is provided both on line- and neutral-side of the generator. The differential currentof the two neutral currents is made externally, and the resultant ∆Io current isconnected to the IED’s. The set of three-phase voltage and differential neutral current,U3P and DIFF_Io, are connected to the inputs.A common operate and start signal from both the directional earth-fault functions andresidual overvoltage protection are connected to an OR-gate to form a combinedearth-fault operate and start signal, which provides a LED indication on the LHMI.Also separate start and operate signals from the both directional earth-fault functionsare connected to the disturbance recorder.The directional earth-fault function is blocked on detection of fuse failure.Section 3 1MRS757582 CREG630 variants34 REG630Application Manual