4–184 869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUALPROTECTION CHAPTER 4: SETPOINTSPhase TimeOvercurrentProtection (51P)The 869 relay TOC element can be configured with any of the IEEE, ANSI, IEC, and IACstandard inverse curves, any of the four FlexCurves, or set to definite time. The selection ofTime Dial Multiplier (TDM) and minimum PKP, helps the user to fine tune the protection foraccurate upstream/downstream coordination and during certain conditions, such asmanual closing and Maintenance.The settings of this function are applied to each of the three phases to produce Pickup andTrip flags per phase. There is no intentional “dead band” when the current is above thePickup level. However the Pickup accuracy is guaranteed within the current inputaccuracy of 1.5% above the set PKP value. The TOC Pickup flag is asserted, when thecurrent on any phase is above the PKP value. The TOC Trip flag is asserted if the elementstays picked up for the time defined by the selected inverse curve and the magnitude ofthe current. The element drops from Pickup without operating if the measured currentdrops below 97 to 98% of the Pickup value before the time for operation is reached. WhenDefinite Time is selected, the time for TOC operation is defined only by the TDM setting.The selection of TDM when in Definite Time mode sets the time to operate in seconds.Path: Setpoints > Protection > Group 1(6) > Current > Phase TOC 1(X)FUNCTIONRange: Disabled, Trip, Alarm, Latched Alarm, ConfigurableDefault: DisabledINPUTRange: Phasor, RMSDefault: PhasorPICKUPRange: 0.050 to 30.000 x CT in steps of 0.001 x CTDefault: 1.000 x CTCURVERange: IEEE Extremely / Very / Moderately Inverse; ANSI Extremely / Very / Normally /Moderately Inverse; Definite time IEC A / B / C and Short Inverse; IAC Extremely / Very /Inverse / Short Inverse; FlexCurve A / B / C / D, I2t, I4tDefault: IEEE Moderately InverseTDMRange: 0.05 to 600.00 in steps of 0.01Default: 1.00The setting provides a selection for Time Dial Multiplier which modifies the operatingtimes per the selected inverse curve. For example, if an IEEE Extremely Inverse curve isselected with TDM = 2, and the fault current is 5 times bigger than the PKP level, theoperation of the element will not occur before 2.59 s have elapsed after Pickup.RESETRange: Instantaneous, TimedDefault: InstantaneousSelection of an Instantaneous or a Timed reset time is provided using this setting. IfInstantaneous reset is selected, the Phase TOC element will reset instantaneouslyproviding the current drops below 97-98% of the Phase TOC PKP level. If Timed reset isselected, the time to reset is calculated based on the reset equation for the selectedinverse curve.DIRECTIONRange: Disabled, Forward (Ph Dir OC 1 FWD), Reverse (Ph Dir OC 1 REV)Default: Disabled
