ABB UniGear Digital, Commissioning And Testing Manual

Page: 41 / 98

PRIM AR Y TESTING VOLTAGE SENSOR S
1VLG5000 17 C 29
4.3 Voltage sensors
Primary testing verifies the whole measurement chain including the sensor, cable connec-
tions and settings of the protection relay. Physical polarity of the voltage sensor is unique,
only one-way installation is possible. Therefore, no polarity (physical test) is needed.
4.3.1 Supervision
In the protection relay, voltage metering is supervised by the VMMXU function. Metering ac-
curacy is stated in Table 3.
Table 3: Voltage metering accuracy
Characteristic Value
Operation accuracy
• Depending on the frequency of the
measured voltage: f
n
±2 Hz
• ±0.5% or ±0.002 × U
n
(at voltages in
range 0.01-1.15 × U
n
)
A measured value under the zero-point clamping limit is forced to zero. This allows the noise
in the input signal to be ignored. Read more details in the technical manual of the protection
relay.
Table 4: Zero-clamping limits
Function Zero-clamping limit
Three-phase voltage measurement (VMMXU) 1% of nominal (Un)
Residual voltage measurement (RESVMMXU) 1% of nominal (Un)
Phase sequence voltage meas. (VSMSQI) 1% of the nominal (Un)