ABB RELION 620 Series Technical Manual page 639

1MAC504801-IB E
620 series ANSI
Technical Manual
Value reporting
The measurement functions are capable of reporting new values for network control
center (SCADA system) based on the following functions:
• Zero-point clamping
• Deadband supervision
• Limit value supervision
In the three-phase voltage measurement function VA, VB, VC the
supervision functions are based on the phase-to-phase voltages. However,
the phase-to-ground voltage values are also reported together with the
phase-to-phase voltages.
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 459: Zero-point clamping limits
Function
Three-phase current measurement (IA, IB, IC)
Three-phase voltage measurement (VA, VB, VC)
Ground current measurement (IG)
Ground voltage measurement (VG)
Phase sequence current measurement (I1, I2, I0)
Phase sequence voltage measurement (V1, V2, V0)
Single-phase power and energy measurement (SP,
SE)
Three-phase power and energy measurement (P, E)
When the frequency measurement function F is unable to measure the
network frequency in the undervoltage situation, the measured values are
set to the nominal and also the quality information of the data set
accordingly. The undervoltage limit is fixed to 10 percent of the nominal
for the frequency measurement.
Measurement functions
Zero-clamping limit
1% of nominal (In)
1% of nominal (Vn)
1% of nominal (In)
1% of nominal (Vn)
1% of the nominal (In)
1% of the nominal (Vn)
1.5% of the nominal (Sn)
1.5% of the nominal (Sn)
Section 7
633