ABB REL670 Product Manual

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ABB REL670 Product Manual Manual pdf 35 page image

function block SMAI. However the main difference is that it canbe used to extract any frequency component from the inputsignal. Thus it can, for example, be used to build sub-synchronous resonance protection for synchronous generator.11. Secondary system supervisionCurrent circuit supervision CCSSPVCOpen or short circuited current transformer cores can causeunwanted operation of many protection functions such asdifferential, earth-fault current and negative-sequence currentfunctions.Current circuit supervision (CCSSPVC) compares the residualcurrent from a three phase set of current transformer cores withthe neutral point current on a separate input taken from anotherset of cores on the current transformer.A detection of a difference indicates a fault in the circuit and isused as alarm or to block protection functions expected to giveinadvertent tripping.Fuse failure supervision FUFSPVCThe aim of the fuse failure supervision function (FUFSPVC) is toblock voltage measuring functions at failures in the secondarycircuits between the voltage transformer and the IED in order toavoid inadvertent operations that otherwise might occur.The fuse failure supervision function basically has three differentdetection methods, negative sequence and zero sequencebased detection and an additional delta voltage and deltacurrent detection.The negative sequence detection algorithm is recommendedfor IEDs used in isolated or high-impedance earthed networks.It is based on the negative-sequence quantities.The zero sequence detection is recommended for IEDs used indirectly or low impedance earthed networks. It is based on thezero sequence measuring quantities.The selection of different operation modes is possible by asetting parameter in order to take into account the particularearthing of the network.A criterion based on delta current and delta voltagemeasurements can be added to the fuse failure supervisionfunction in order to detect a three phase fuse failure, which inpractice is more associated with voltage transformer switchingduring station operations.Fuse failure supervision VDSPVCDifferent protection functions within the protection IEDoperates on the basis of measured voltage at the relay point.Some example of protection functions are:• Distance protection function.• Undervoltage function.• Energisation function and voltage check for the weakinfeed logic.These functions can operate unintentionally, if a fault occurs inthe secondary circuits between voltage instrumenttransformers and the IED. These unintentional operations canbe prevented by fuse failure supervision (VDSPVC).VDSPVC is designed to detect fuse failures or faults in voltagemeasurement circuit, based on phase wise comparison ofvoltages of main and pilot fused circuits. VDSPVC blockingoutput can be configured to block functions that need to beblocked in case of faults in the voltage circuit.12. ControlSynchrocheck, energizing check, and synchronizing SESRSYNThe Synchronizing function allows closing of asynchronousnetworks at the correct moment including the breaker closingtime, which improves the network stability.Synchrocheck, energizing check, and synchronizing(SESRSYN) function checks that the voltages on both sides ofthe circuit breaker are in synchronism, or with at least one sidedead to ensure that closing can be done safely.SESRSYN function includes a built-in voltage selection schemefor double bus and 1½ breaker or ring busbar arrangements.Manual closing as well as automatic reclosing can be checkedby the function and can have different settings.For systems, which can run asynchronously, a synchronizingfeature is also provided. The main purpose of the synchronizingfeature is to provide controlled closing of circuit breakers whentwo asynchronous systems are in phase and can be connected.The synchronizing feature evaluates voltage difference, phaseangle difference, slip frequency and frequency rate of changebefore issuing a controlled closing of the circuit breaker.Breaker closing time is a setting.Autorecloser SMBRRECThe auto reclosing function provides:• high-speed and/or delayed auto reclosing• single and/or three phase auto reclosing• support for single or multi-breaker applications.The auto recloser can be used for delayed busbar restoration.Up to five reclosing shots can be performed. The first shot canbe single-, two-, and /or three-phase depending on the type ofthe fault and the selected auto reclosing mode.Several auto reclosing functions can be provided for multi-breaker arrangements. A priority circuit allows one circuit1MRK 506 372-BEN -Line distance protection REL670 2.2Product version: 2.2ABB 35