2. Basic Operation
On connecting power supply the display shows all of the segments, then gradually screens with the instrument type and
setting of basic parameters
1.
line 1 :
1
3
3
- instrument type number
line 2 :
5
A
- current input type
line 3 :
r
I
- digital output type : relay (
r
), solid-state (
I
), or none (
n
)
2.
when connection of voltage via voltage transformers set (otherwise the screen is skipped) :
line 1 :
U
t
- voltage transformer connected identification
line 2 : nominal primary voltage [kV]
line 3 : nominal secondary voltage [kV]
3.
line 1 :
C
t
- current transformer/range specification
line 2 : nominal primary current [A]
line 3 : nominal secondary current [A]
4.
line 1 :
F
U
- nominal frequency and voltage
line 2 : nominal frequency
line 3 : nominal voltage
Then the instrument starts display actual measured values. Simultaneously, if the instrument has a communication line, it can
be set and its measured values read via the communication link using a PC.
2.1 Setup
At this moment it is necessary to set
instrument parameters
that are essential for proper instrument measurement :
•
CT ratio – parameter 01 (and its multiplier, optionally)
•
type of connection – parameter 02 (wye, delta, Aron)
•
mode of connection – parameter 04 (direct or via VT connection, VT ratio and multiplier, optionally)
•
nominal frequency
f
NOM
and nominal voltage
U
NOM
– double parameter 05
Usually, it is only necessary to adjust the CT ratio. Next example shows how to do it :
Assuming that the ratio of used CTs is 750/1 A. First off all, it is necessary to switch display from measured data branch (the
ULN screen on the example below) to
the parameter branch
with the
button. The branch is indicated with the
symbol
. Parameter 01 appears – this parameter is the CT ratio and its default value is 5/5 A.