ABB RELION REX640 Technical Manual page 1295

1MRS759142 C
REX640
Technical Manual
Value reporting
The measurement functions are capable of reporting new values for network control
center (SCADA system) based on various functions.
• Zero-point clamping
• Deadband supervision
• Limit value supervision
In the three-phase voltage measurement function VMMXU the
supervision functions are based on the phase-to-phase voltages.
However, the phase-to-earth voltage values are also reported with the
phase-to-phase voltages.
GOOSE is an event based protocol service. Analog GOOSE uses the
same event generation functions as vertical SCADA communication
for updating the measurement values. Update interval of 500 ms is
used for data that do not have zero-point clamping, deadband
supervision or limit value supervision.
Zero-point clamping
A measured value under the zero-point clamping limit is forced to zero. This allows
the noise in the input signal to be ignored. The active clamping function forces both
the actual measurement value and the angle value of the measured signal to zero. In the
three-phase or sequence measuring functions, each phase or sequence component has
a separate zero-point clamping function. The zero-value detection operates so that
once the measured value exceeds or falls below the value of the zero-clamping limit,
new values are reported.
Table 1209: Zero-point clamping limits
Function
Three-phase current measurement (CMMXU)
Three-phase voltage measurement (VMMXU)
Residual current measurement (RESCMMXU)
Residual voltage measurement (RESVMMXU)
Phase sequence current measurement (CSMSQI)
Phase sequence voltage measurement
(VSMSQI)
Three-phase power and energy measurement
(PEMMXU)
When the frequency measurement function FMMXU is unable to
measure the network frequency in the undervoltage situation, the
Measurement functions
Zero-clamping limit
1% of nominal (In)
1% of nominal (Un)
1% of nominal (In)
1% of nominal (Un)
1% of the nominal (In)
1% of the nominal (Un)
1.5% of the nominal (Sn)
Section 8
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