ABB REF542plus - Current Sensor; Voltage Sensor; Testing the Measured Value Recording

Multifunction Protection and Switchgear Control unit REF542plus
Manual: Motor Protection with ATEX-Certification
Every core must be tested here.
If the Variac described in the current transformer section for recording the magnetiz-
ing characteristic has a sufficiently high output voltage (e.g. 500 V), it can also be
used to run a qualitative test of the voltage transformer transformation ratio. The
Variac voltage is applied to the primary side of the voltage transformer and a voltme-
ter is used to measure the secondary voltage at the corresponding transformer or pro-
tective cabinet terminals.
8.5.3 Current sensor
Because the current sensor, the Rogowski coil, is an air-core coil, it must be sub-
jected to the same polarity test as the current transformers.
The test design is shown in the following diagram. A higher voltage value may be re-
quired for the battery.
+
–
P2
P1
V
+
–
S2
S1
Figure 28: Polarity test of current sensors (Rogowski coil)
The transformation ratio is tested exactly as with a current transformer. The display in
the REF542 protection and control unit can also be checked at the same time. It is not
necessary to record a magnetizing characteristic with the Rogowski coil, because it is
an air-core coil with no saturation characteristics.
8.5.4 Voltage sensor
The polarity of the voltage sensor, which is a resistive precision voltage divider, is
checked as shown in the following diagram. The correct polarity of the voltage is
measured by applying an appropriate DC voltage (e.g. 24V/DC) to the secondary
terminals. The auxiliary voltage source can also be used if the transformation ratio is
very high. The transformation ratio of the resistive divider is checked at the same
time.
+
–
N
A
V
+
–
n
a
Figure 29: Polarity test of voltage sensors (resistive splitter)
8.6 Testing the measured value recording
Proper functioning of the transformers and sensors is important for proper functioning
of the REF542plus. The measured-value processing of the unit and the set rated val-
ues must be tested for this reason.
1VTA100114-Rev. 04 en PTMV, 19.01.05 Motorprotection 53 / 66
Valid from Version V4D02