REF 542plus switchbay protection and control unit
Manual Part 3: Installation and Commissioning
1VTA100004-en DMS,2001-10-04
REF542
plus
: Installation and Commissioning
37 / 80
5.5.4 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 19:
Polarity test of voltage sensors (resistive splitter)
5.6 Testing the measured value recording
Proper functioning of the transformers and sensors is important for proper functioning
of the REF542
plus
. The measured-value processing of the unit and the set rated val-
ues must be tested for this reason.
The phase currents and phase voltages must be taken as measured input quantities.
All other measured values are quantities derived from them.
Test as follows:
Check whether the set rated values match the rated values required by the user (in
the order documentation).
If necessary, load the application into the PC from the REF542
plus
.
Select the menu item
Main Menu/Settings/Connections/Analog Inputs
in
the configuration program. The rated values are shown in the dialog window that ap-
pears and, if necessary, changed.
Test the wiring of the transformers or sensors
Disconnect the transducers or sensors from the REF542
plus
.
The current transformers must be short-circuited, combination sensors disconnected.
Connect the test set to the REF542
plus
. The relevant current and voltage signals are
applied to the analog inputs.
Set the required rated values on the test set
Table 11:
Rated values of the current and voltage signals
Transducer/sensor
Rated value
Current transformer
1A or 5A
Voltage Transformer
100V
Rogowski coil
150 mV
Voltage sensor
2V
