DPMS XPQ, User Manual

Page: 21 / 134

19
POWER INSTRUMENTS
used. A fuse (typical 1A/250Vac) should be used in the voltage input loop. A PT
should be used to transform the high voltage into the measurement range of the
meter if it is used in a high voltage system. The wire gauge of the input voltage
should be AWG16~12 or 1.3~2.0mm
2
.
Note: In no circumstances should the PT secondary be shorted. The PT
secondary should be well grounded at one end.
Current Input
In a practical engineering application, CTs should be installed in the
measuring loop. Normally the CT secondary is 5A. 1A is possible as an option.
A CT accuracy over 0.5% (rating over 3VA) is recommended and it will influence
the measuring accuracy. The wire between the CT and meter should be as short
as possible. The length of the wire may increase the error of the measurement.
CTs must be required for rated current over 5A.
The wire guage of the input current should be AWG15~10 or 1.5~2.5mm
2
.
Note: The CT loop should not be open in any circumstances when the power
is on. There should not be any fuse or switch in the CT loop and one end of the
CT loop should be connected to the ground.
Vn Connection
Vn is the reference point of meter input voltage. The lower the wire
resistance the lower the error.
Three phase wiring diagram
The DPMS XPQ can satisfy most kinds of three phase wiring diagrams.
Please read this part carefully before you begin to do the wiring so that you may
chose a wiring diagram suitable for your power system.