5-192 M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUALGROUPED ELEMENTS CHAPTER 5: SETTINGS5The sensitive directional power element responds to three-phase directional power and is designed for reverse power andlow forward power applications for synchronous machines or interconnections involving co-generation. The relaymeasures the three-phase power from either a full set of wye-connected VTs or a full set of delta-connected VTs. In thelatter case, the two-wattmeter method is used. See the UR-series Metering Conventions section in chapter 6 for detailsregarding the active and reactive powers used by the sensitive directional power element.The element has an adjustable characteristic angle and minimum operating power as shown in the Directional PowerCharacteristic diagram that follows. The element responds to the following condition:Eq. 5-28whereP and Q are active and reactive powers as measured per the UR metering convention is a sum of the element characteristic (DIR POWER 1 RCA) and calibration (DIR POWER 1 CALIBRATION) anglesSMIN is the minimum operating powerThe operating quantity is displayed in the ACTUAL VALUES METERING SENSITIVE DIRECTIONAL POWER 1(2) actual value.The element has two independent (as to the pickup and delay settings) stages for alarm and trip, respectively.Figure 5-103: Directional power characteristicBy making the characteristic angle adjustable and providing for both negative and positive values of the minimumoperating power, a variety of operating characteristics can be achieved as presented in the following figure. For example,section (a) in the figure shows settings for reverse power, while section (b) shows settings for low forward powerapplications. DIR POWER 1EVENTS: DisabledRange: Disabled, EnabledP cos Q sin+ SMIN>842701A1.CDRRESTRAINSMINRCA+CALIBRATION+-OPERATEDirectionQP
