ABB RELION 620 Series Technical Manual page 646

Section 7
Measurement functions
7.1.4
7.1.4.1
7.1.4.2
640
periodic comparison of the measured value from the protection relay 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 IA, IB, IC
Identification
Function description
Three-phase current measurement
Function block
A070777-ANSI V1 EN
Figure 324: Function block
IEC 61850 IEC 60617
identification identification
CMMXU 3I
1MAC504801-IB E
ANSI/IEEE C37.2
device number
IA,IB,IC
620 series ANSI
Technical Manual