Measurement Function Applications; Three-Phase Current Measurement Cmmxu; Identification - ABB Relion SMU615 Technical Manual

1MRS758407 B
7.1.3
7.1.4
7.1.4.1
SMU615
Technical Manual
Sequence components
The phase-sequence components are calculated using the phase currents and phase
voltages. More information on calculating the phase-sequence components can be
found in Calculated measurements

Measurement function applications

The measurement functions are used for power system measurement, supervision and
reporting to a monitoring tool within PCM600or to the station level, for example, with
IEC 61850. The possibility to continuously monitor the measured values of active
power, reactive power, currents, voltages, power factors and so on, is vital for efficient
production, transmission, and distribution of electrical energy. It provides a fast and
easy overview of the present status of the power system to the system operator.
Additionally, it can be used during testing and commissioning of merging units to
verify the proper operation and connection of instrument transformers, that is, the
current transformers (CTs) and voltage transformers (VTs). The proper operation of
the merging unit analog measurement chain can be verified during normal service by
a periodic comparison of the measured value from the merging unit to other
independent meters.
When the zero signal is measured, the noise in the input signal can still produce small
measurement values. The zero point clamping function can be used to ignore the noise
in the input signal and, hence, prevent the noise to be shown in the user display. The
zero clamping is done for the measured analog signals and angle values.
The demand values are used to neglect sudden changes in the measured analog signals
when monitoring long time values for the input signal. The demand values are linear
average values of the measured signal over a settable demand interval. The demand
values are calculated for the measured analog three-phase current signals.
The limit supervision indicates, if the measured signal exceeds or goes below the set
limits. Depending on the measured signal type, up to two high limits and up to two low
limits can be set for the limit supervision.
The deadband supervision reports a new measurement value if the input signal has
gone out of the deadband state. The deadband supervision can be used in value
reporting between the measurement point and operation control. When the deadband
supervision is properly configured, it helps in keeping the communication load in
minimum and yet measurement values are reported frequently enough.

Three-phase current measurement CMMXU

Identification

Function description
Three-phase current measurement
Measurement functions
in this manual.
IEC 61850 IEC 60617
identification identification
CMMXU 3I
Section 7
ANSI/IEEE C37.2
device number
3I
179