Sequence componentsThe phase-sequence components are calculated using the phase currents and phasevoltages. More information on calculating the phase-sequence components can befound in Calculated measurements in this manual.8.1.3 Measurement function applicationsThe measurement functions are used for power system measurement, supervision andreporting to LHMI, a monitoring tool within PCM600, or to the station level, forexample, with IEC 61850. The possibility to continuously monitor the measuredvalues of active power, reactive power, currents, voltages, power factors and so on, isvital for efficient production, transmission, and distribution of electrical energy. Itprovides a fast and easy overview of the present status of the power system to thesystem operator. Additionally, it can be used during testing and commissioning ofprotection relays to verify the proper operation and connection of instrumenttransformers, that is, the current transformers (CTs) and voltage transformers (VTs).The proper operation of the protection relay analog measurement chain can be verifiedduring normal service by a periodic comparison of the measured value from theprotection relay to other independent meters.When the zero signal is measured, the noise in the input signal can still produce smallmeasurement values. The zero point clamping function can be used to ignore the noisein the input signal and, hence, prevent the noise to be shown in the user display. Thezero clamping is done for the measured analog signals and angle values.The demand values are used to neglect sudden changes in the measured analog signalswhen monitoring long time values for the input signal. The demand values are linearaverage values of the measured signal over a settable demand interval. The demandvalues are calculated for the measured analog three-phase current signals.The limit supervision indicates, if the measured signal exceeds or goes below the setlimits. Depending on the measured signal type, up to two high limits and up to two lowlimits can be set for the limit supervision.The deadband supervision reports a new measurement value if the input signal hasgone out of the deadband state. The deadband supervision can be used in valuereporting between the measurement point and operation control. When the deadbandsupervision is properly configured, it helps in keeping the communication load inminimum and yet measurement values are reported frequently enough.8.1.4 Three-phase current measurement CMMXU8.1.4.1 IdentificationFunction description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberThree-phase current measurement CMMXU 3I 3I1MRS758755 A Section 8Measurement functionsREC615 and RER615 561Technical Manual
