GE L60 Instruction Manual

Also see for L60: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

Contents

5-10 L60 Line Phase Comparison Relay GE Multilin5.2 PRODUCT SETUP 5 SETTINGS5tuted with zero. This applies to phase and ground current phasors as well as true RMS values and symmetrical compo-nents. The cut-off operation applies to quantities used for metering, protection, and control, as well as those used bycommunications protocols. Note that the cut-off level for the sensitive ground input is 10 times lower that the CURRENTCUT-OFF LEVEL setting value. Raw current samples available via oscillography are not subject to cut-off.• VOLTAGE CUT-OFF LEVEL: This setting modifies the voltage cut-off threshold. Very low secondary voltage measure-ments (at the fractional volt level) can be affected by noise. Some customers prefer these low voltages to be displayedas zero, while others prefer the voltage to be displayed even when the value reflects noise rather than the actual sig-nal. The L60 applies a cut-off value to the magnitudes and angles of the measured voltages. If the magnitude is belowthe cut-off level, it is substituted with zero. This operation applies to phase and auxiliary voltages, and symmetricalcomponents. 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.3-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