GE G60 Instruction Manual

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GE Multilin G60 Generator Management Relay 5-55 SETTINGS 5.1 OVERVIEW5• TARGET setting: This setting is used to define the operation of an element target message. When set to Disabled, notarget message or illumination of a faceplate LED indicator is issued upon operation of the element. When set to Self-Reset, the target message and LED indication follow the Operate state of the element, and self-resets once the oper-ate element condition clears. When set to Latched, the target message and LED indication will remain visible after theelement output returns to logic 0 - until a RESET command is received by the relay.• EVENTS setting: This setting is used to control whether the Pickup, Dropout or Operate states are recorded by theevent recorder. When set to Disabled, element pickup, dropout or operate are not recorded as events. When set toEnabled, events are created for:(Element) PKP (pickup)(Element) DPO (dropout)(Element) OP (operate)The DPO event is created when the measure and decide comparator output transits from the pickup state (logic 1) tothe dropout state (logic 0). This could happen when the element is in the operate state if the reset delay time is not ‘0’.5.1.3 INTRODUCTION TO AC SOURCESa) BACKGROUNDThe G60 may be used on systems with breaker-and-a-half or ring bus configurations. In these applications, each of the twothree-phase sets of individual phase currents (one associated with each breaker) can be used as an input to a breaker fail-ure element. The sum of both breaker phase currents and 3I_0 residual currents may be required for the circuit relayingand metering functions. For a three-winding transformer application, it may be required to calculate watts and vars for eachof three windings, using voltage from different sets of VTs. These requirements can be satisfied with a single UR, equippedwith sufficient CT and VT input channels, by selecting the parameter to measure. A mechanism is provided to specify theAC parameter (or group of parameters) used as the input to protection/control comparators and some metering elements.Selection of the parameter(s) to measure is partially performed by the design of a measuring element or protection/controlcomparator by identifying the type of parameter (fundamental frequency phasor, harmonic phasor, symmetrical component,total waveform RMS magnitude, phase-phase or phase-ground voltage, etc.) to measure. The user completes the processby selecting the instrument transformer input channels to use and some of the parameters calculated from these channels.The input parameters available include the summation of currents from multiple input channels. For the summed currents ofphase, 3I_0, and ground current, current from CTs with different ratios are adjusted to a single ratio before summation.A mechanism called a “Source” configures the routing of CT and VT input channels to measurement sub-systems.Sources, in the context of UR series relays, refer to the logical grouping of current and voltage signals such that one sourcecontains all the signals required to measure the load or fault in a particular power apparatus. A given source may contain allor some of the following signals: three-phase currents, single-phase ground current, three-phase voltages and an auxiliaryvoltage from a single VT for checking for synchronism.To illustrate the concept of Sources, as applied to current inputs only, consider the breaker-and-a-half scheme below. In thisapplication, the current flows as shown by the arrows. Some current flows through the upper bus bar to some other locationor power equipment, and some current flows into transformer Winding 1. The current into Winding 1 is the phasor sum (ordifference) of the currents in CT1 and CT2 (whether the sum or difference is used depends on the relative polarity of the CTconnections). The same considerations apply to transformer Winding 2. The protection elements require access to the netcurrent for transformer protection, but some elements may need access to the individual currents from CT1 and CT2.