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3 FACTORY INSTALLATION AND CALIBRATION OF THE PQSENSOR™
Only the Measurement Unit is permanently installed in the CVT in the factory - the Intercon-
necting Cable and the SCM should be installed as part of the site installation and commission-
ing procedure. However, for test purposes, the SCM must be connected to the CVT, usually us-
ing a dedicated cable installed in the factory test bay to permit the PQSensor™ to be calibrated
when rated voltage is applied to the CVT.
3.1 Measurement Unit Installation
See Section 2 for details of the Measurement Unit (MU) installation.
3.2 Factory Calibration Of The PQSensor™
To perform the calibration of the PQSensor™ SCM it must be wired to the Measurement Unit
installed in the CVT terminal box as shown in the wiring diagram in Appendix IV.
This can be done using the Interconnecting cable provided with the PQSensor™ or for factory
testing a dedicated Interconnection Cable between the CVT test bay and the SCM under test/
calibration can be used. This cable must be twin twisted pair cable with individual and collective
screens connected as shown in the wiring diagram in Appendix IV.
A suitable supply voltage must be connected to the PQSensor™ SCM on terminals 4 & 5 - this
can be 110V - 230V ac or 110V dc - this supply input is not polarity sensitive. Terminal 3 must
be grounded.
This calibration process involves adjusting the output of the PQSensor™ so that it delivers its
Nominal Output Voltage when the CVT is energised with nominal substation voltage.
With the CVT energised with nominal substation voltage measure the SCM output voltage on
terminals 4 & 5 with a calibrated true rms voltmeter. Using the output adjust potentionmeter set
the output voltage to be equal to the PQSensor Nominal Output Voltage as given in the PQSen-
sor Test report.
N.B. Record the results on the calibration label inside the PQSensor. Also record the serial
number of the CVT on the same label to ensure that at site the PQSensor™ is installed on the
CVT with which it has been calibrated.
4 SITE INSTALLATION AND TESTING OF THE PQSENSOR™
4.1 Mounting The SCM Enclosure.
The signal conditioning module (SCM) box is a weatherproof IP65 enclosure, with approxi-
mate dimensions of 260mm x 160mm x 90mm. For full details of dimensions and mounting
hole locations see Appendix II. The SCM box is typically installed on the CVT support structure
in a vertical position with the cable entries on the bottom face. There must be a solid ground
connection between the SCM enclosure and the CVT structure, This is usually achieved by
making a ground connection to the CVT structure using the earth tag provided as part of the
interconnection cable gland kit.
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