5-14 T60 Transformer Protection System GE Multilin5.2 PRODUCT SETUP 5 SETTINGS5components. The cut-off operation applies to quantities used for metering, protection, and control, as well as thoseused by communications protocols. Raw samples of the voltages available via oscillography are not subject cut-off.The CURRENT CUT-OFF LEVEL and the VOLTAGE CUT-OFF LEVEL are used to determine the metered power cut-off levels. Thepower cut-off level is calculated as shown below. For Delta connections:(EQ 5.3)For Wye connections:(EQ 5.4)(EQ 5.5)where VT primary = VT secondary × VT ratio and CT primary = CT secondary × CT ratio.For example, given the following settings:CURRENT CUT-OFF LEVEL: “0.02 pu”VOLTAGE CUT-OFF LEVEL: “1.0 V”PHASE CT PRIMARY: “100 A”PHASE VT SECONDARY: “66.4 V”PHASE VT RATIO: “208.00 : 1"PHASE VT CONNECTION: “Delta”.We have:CT primary = “100 A”, andVT primary = PHASE VT SECONDARY x PHASE VT RATIO = 66.4 V x 208 = 13811.2 VThe power cut-off is therefore:power cut-off = (CURRENT CUT-OFF LEVEL × VOLTAGE CUT-OFF LEVEL × CT primary × VT primary)/VT secondary= ( × 0.02 pu × 1.0 V × 100 A × 13811.2 V) / 66.4 V= 720.5 wattsAny calculated power value below this cut-off will not be displayed. As well, the three-phase energy data will not accumu-late if the total power from all three phases does not exceed the power cut-off.Lower the VOLTAGE CUT-OFF LEVEL and CURRENT CUT-OFF LEVEL with care as the relay accepts lower signalsas valid measurements. Unless dictated otherwise by a specific application, the default settings of “0.02pu” for CURRENT CUT-OFF LEVEL and “1.0 V” for VOLTAGE CUT-OFF LEVEL are recommended.5.2.3 CLEAR RELAY RECORDSPATH: SETTINGS PRODUCT SETUP CLEAR RELAY RECORDS CLEAR RELAY RECORDSCLEAR USER REPORTS:OffRange: FlexLogic™ operandMESSAGE CLEAR EVENT RECORDS:OffRange: FlexLogic™ operandMESSAGE CLEAR OSCILLOGRAPHY?NoRange: FlexLogic™ operandMESSAGE CLEAR DATA LOGGER:OffRange: FlexLogic™ operandMESSAGE CLEAR ARC AMPS 1:OffRange: FlexLogic™ operandMESSAGE CLEAR ARC AMPS 2:OffRange: FlexLogic™ operand3-phase power cut-off 3 CURRENT CUT-OFF LEVEL× VOLTAGE CUT-OFF LEVEL VT primary× CT primary××VT secondary------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------=3-phase power cut-off 3 CURRENT CUT-OFF LEVEL× VOLTAGE CUT-OFF LEVEL VT primary× CT primary××VT secondary--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------=per-phase power cut-off CURRENT CUT-OFF LEVEL VOLTAGE CUT-OFF LEVEL VT primary× CT primary××VT secondary----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------=3NOTE
