GE 469 Instruction Manual

Also see for Masoneilan 469 Series: Instruction manual Instruction manual Communications guide Instruction manual Instruction manual

Contents

5–18 469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUALCHAPTER 5: SETTINGSinput should be used for either zero-sequence or residual ground sensing. If theconnection is residual, the Ground CT secondary and primary values should be the sameas the phase CT. If however, the connection is zero-sequence, the Ground CT secondaryand primary values must be entered. The Ground CT primary should be selected such thatpotential fault current does not exceed 20 times the primary rating. When relaying classCTs are purchased, this precaution will ensure that the Ground CT does not saturate underfault conditions.The PHASE DIFFERENTIAL CT PRIMARY must be entered if the differential feature is to beused. If two CTs are used per phase in a vectorial summation configuration, the CTs shouldbe chosen to ensure there is no saturation during motor starting. If however, a corebalance CT is used for the differential protection in each phase, a low CT rating of 50 or 100A allows for very sensitive differential protection.When the two-speed motor feature is used, a value for a second set of Phase CTs andmotor FLA must be entered here for Speed 2. If the Phase CTs are the same as the speed 1phase CTs, simply enter the same value here as well.Example 1:Consider a 469 with a 5 A Phase CT secondary and Ground Fault Detection set to Residualand a motor with the following specifications:Motor Nameplate FLA: 87 A; Low Resistance Grounded; Maximum Fault: 400 AThe following settings are required:PHASE CT PRIMARY: “100”MOTOR FULL LOAD AMPS: “87”GROUND CT: “5 A Secondary”GROUND CT PRIMARY: “100”Example 2:Consider a 469 with a 5 A Phase CT secondary and Ground Fault Detection set to Residualand a motor with the following specifications:Motor Nameplate FLA: 255 A; Solidly Grounded; Maximum Fault: 10000 A;Zero Sequence Ground CT: (10000/20) 500:1The following settings are required:PHASE CT PRIMARY: “300”MOTOR FULL LOAD AMPS: “255”GROUND CT: “5 A Secondary”GROUND CT PRIMARY: “500”Example 3:Again, consider a 469 with a 5 A Phase CT secondary and Ground Fault Detection set toResidual and a motor with the following specifications:Motor Nameplate FLA: 330 A; High Resistance Grounded; Maximum Fault: 5 AThe following settings are required: