88 9424200994 Rev Nbe specified on the System Parameters, Sensing Transformers screen in BESTCOMSPlus. Refer to theConfiguration chapter for more information.CT SourceThe CT Source setting configures an instantaneous overcurrent element to monitor CT circuit 1 or CTcircuit 2 on protection systems equipped with two sets of CTs. CT circuit 1 terminals are designated D1(IA1) through D8 (IG1) and CT circuit 2 terminals are designated F1 (IA2) through F8 (IG2). For anillustration, refer to the Terminals and Connectors chapter.DirectionAn instantaneous overcurrent element can be configured for forward or reverse tripping. Refer to theDirectional Overcurrent Protection (67) chapter for more information.Pickup and TripThe Pickup output occurs first, followed by the Trip output.PickupThe Pickup output becomes true when the measured current increases above the current thresholdestablished by the Pickup setting. In BESTlogicPlus, the Pickup output can be connected to other logicelements to annunciate the condition, control other elements in logic, and start the fault recorder (logicelement FAULTTRIG).Assertion of the Pickup output initiates a timer that begins timing to a trip. The duration of the timer isestablished by the Time Delay setting. A Time Delay of zero (0) makes the 50 element instantaneous withno intentional time delay.If the pickup condition subsides before the element delay expires, the timer and Pickup output are reset,no corrective action is taken, and the element is rearmed for any other occurrences of overcurrent.TripThe Trip output becomes true if an overcurrent condition persists for the duration of the element TimeDelay setting. In BESTlogicPlus, the Trip output can be connected to other logic elements and to aphysical relay output to annunciate the condition and to initiate corrective action. If a target is enabled forthe element, the BE1-11g will record a target when the Trip output becomes true. See the Fault Reportingchapter for more information about target reporting.Element BlockingThe Block input provides logic-supervision control of the element. When true, the Block input disables theelement by forcing the Trip and Pickup outputs to logic 0 and resetting the element timer. Connect theelement Block input to the desired logic in BESTlogicPlus. When the element is initially selected from theElements view, the default condition of the Block input is a logic 0.Logic ConnectionsInstantaneous overcurrent element logic connections are made on the BESTlogicPlus screen inBESTCOMSPlus. The instantaneous overcurrent element logic block is illustrated in Figure 58. Logicinputs and outputs are summarized in Table 29.Figure 58. Instantaneous Overcurrent Element Logic BlockInstantaneous Overcurrent (50) Protection BE1-11g
