CT Lab Vecto III, User Manual

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Vecto III User Manual
18
2.3.2 Vecto III External Interfaces
2.3.2.1 Voltages
The voltage inputs to the Vecto III interface directly to 110 V VT circuits or directly to
a mains connection, which has to be less than 600 V line to neutral.
•
Voltage measurements are differential.
•
6 input terminals for voltages are used.
•
The first 4 terminals are used for 3 voltage inputs V
1
, V
2
and V
3
and are
neutral (V
com
) referenced (V
1
-N, V
2
-N, V
3
-N).
•
Input channel 1-3 is referenced to a neutral (4th terminal) connection. This
4th terminal acts as a reference channel and can be any phase voltage if a 3-
phase line-line voltage circuit is measured.
•
If it is a 3-phase line-neutral voltage circuit, then the 4th terminal will be
connected to the neutral voltage.
•
The 5th and 6th terminal is the 4th differential channel.
•
It can be used to for example measure the difference between neutral and
earth.
2.3.2.2 Currents
Permanently installed 1 A or 5 A CT’s, or clamp - on CT’s interface directly to the
galvanically isolated current inputs.
The device calculates the “missing current” by assuming the sum of all currents is zero.
(Please refer to Section 2.4.5 for more info)
Alternatively, 1 V
RMS
voltage output current transducers or Rogowski coils with 5 V
DC
power supply can be used to measure current.
Current to voltage transducers can interface directly to 4 low voltage differential
inputs. (Please refer to Section 2.4.6 for more info)
2.3.3 Power sources
The device is powered from a power factor corrected AC supply input (90 – 300 V
AC/DC).
It can also be powered from an IEEE 802.3-2008 compliant PoE Plus (< 12 W) source.