GE M60 Instruction Manual

Also see for M60: Communications manual Communications guide Instruction manual Instruction manual

Contents

CHAPTER 5: SETTINGS GROUPED ELEMENTSM60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL 5-1895The characteristic allows for very sensitive settings when fault current is low and less sensitive settings when fault currentis high and CT performance can produce incorrect operate signals.STATOR DIFF LINE END SOURCE — This setting selects the source connected to CTs in the end of the machine stator windingclosest to the load and farthest from the winding neutral point. Wire both line and neutral-side CTs to measure theircurrents in the same direction with respect to the neutral point of the winding.If the two-speed motor functionality is employed with two separate CTs at each speed, the source that is sum of currentsof two CT banks at line side should be assigned with this setting for proper differential functionality.STATOR DIFF NEUTRAL END SOURCE — Selects the source connected to CTs in the end of the machine stator winding farthestfrom the load and closest to the winding neutral point. Wire both line and neutral-side CTs to measure their currents in thesame direction with respect to the neutral point of the winding.STATOR DIFF PICKUP — Defines the minimum differential current required for operation. This setting is based on the amountof differential current that can be seen under normal operating conditions. A setting of 0.1 to 0.3 pu is generallyrecommended.STATOR DIFF SLOPE 1 — This setting is applicable for restraint currents from zero to STATOR DIFF BREAK 1, and it defines theratio of differential to restraint current above which the element operates. This slope is set to ensure sensitivity to internalfaults at normal operating current levels. The criteria for setting this slope is to allow for maximum expected CT mismatcherror when operating at the maximum permitted current. This maximum error is generally in the range of 5 to 10% of CTrating.STATOR DIFF BREAK 1 — Defines the end of the Slope 1 region and the start of the transition region. Set it just above themaximum normal operating current level of the machine.STATOR DIFF SLOPE 2 — This setting is applicable for restraint currents above the STATOR DIFF BREAK 2 setting when theelement is applied to generator stator windings. This slope is set to ensure stability under heavy external fault conditionsthat can lead to high differential currents as a result of CT saturation. A setting of 80 to 100% is recommended. Thetransition region (as shown on the characteristic plot) is a cubic spline, automatically calculated by the relay to result in asmooth transition between STATOR DIFF SLOPE 1 and STATOR DIFF SLOPE 2 with no discontinuities.STATOR DIFF BREAK 2 — This setting defines the end of the transition region and the start of the Slope 2 region. Set it to thelevel at which any of the protection CTs are expected to begin to saturate.Figure 5-100: Stator differential logicSETTING SETTINGSFLEXLOGIC OPERANDSFLEXLOGIC OPERANDSFLEXLOGIC OPERANDSSETTINGSETTINGSETTINGSTATOR DIFFFUNCTION:STATOR DIFFSLOPE 2:STATOR DIFFBREAK 1:STATOR DIFFBREAK 2:STATOR DIFFSLOPE 1:STATOR DIFFPICKUP:STATOR DIFF PKP ASTATOR DIFF PKP BSTATOR DIFF PKP CSTATOR DIFF DPO ASTATOR DIFF DPO BSTATOR DIFF DPO CSTATOR DIFF BLOCK:Off = 0Enabled = 1STATOR DIFFLINE END SOURCE:STATOR DIFFNEUTRAL END SOURCE:IAIAIBIBICICRUNRUNRUNIadIbdIcdIarIbrIcr 830000A5.CDRANDRestraint PhasorsDifferential PhasorsDC OffsetRemovalD.F.T.andDifferentialand RestraintIarIadIbrIbdIcrIcd