Basler BE1-67 Instruction Manual

Also see for BE1-67: Instructions

Basler BE1-67 Instruction Manual Manual pdf 8 page image

1-2 General Information BE1-67Figure 1-2. Trip Direction DefinedTwelve standard time-current characteristic curves are available to aid in the coordination of this relay withother protective devices in the system. These include seven characteristic curves that are standard in NorthAmerica and five that are compatible with British or IEC standards requirements. In addition, an option allowsthe relay to be supplied with all of these curves any of which may be switch selected to suit requirements atthe time of installation.Table 1-1. Selection Considerations For Characteristic CurvesStyleDesignationCharacteristicShape Special CharacteristicsB1 Short Inverse Relatively short time, desirable wherepreserving system stability is a criticalfactor.B2, E2 Long Inverse Provides protection for starting motors andoverloads of short duration.B3 Definite Time Definite Time Fixed time delay according tothe time dial setting. Useful for sequentialtripping schemes.B4, E4 Moderately Inverse Accommodates moderate load changes asmay occur on parallel lines where one linemay occasionally have to carry both loads.B5, E5 Inverse Provide additional variations of the inversecharacteristic, thereby allowing flexibility inmeeting load variations, or in coordinatingwith other relays.B6. E6 Very InverseB7, E7 Extremely InverseIf the supply to the protected portion of the system is constant, and if the magnitude of the fault current isdetermined primarily by the location of the fault on the line, the selection of a more inverse time characteristicis more desirable to provide selective coordination with adjacent line protection. However, if the capacity ofthe supply varies significantly over a period (such as a day), a less inverse time or even the definite timecharacteristic, may be preferred to provide smoother coordination.LIMITED REGION OF OPERATIONA limited region-of-operation option is available toprovide additional protection against false trippingon mutually coupled lines. Faults on adjacent linesthat share the same poles, towers or right-of-waymay induce currents on the protected line whichappear as fault currents in the tripping direction.The limited region of operation mode providesdiscrimination between faults on the protected lineand faults on the adjacent line. To order this option,specify option 3-5 or 3-6.One consideration in applying a phase directionalovercurrent relay is the definition of trip direction.For most applications, the setting of the relaydirectional element is based upon the impedancecharacteristics of a given circuit. This angle is thenused as the maximum torque angle and any currentflowing in the half-plane defined by this angle isconsidered to be in the trip direction.