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TO 172838
5.1 .4 Potential T ransformer's Ratio
include optional, user-provided potential transformers. Their
ratios must be taken into account by means of settings on
Switch
SW2, Nos. 1, 2, 3 and 4,
When external potential transformers are used, calculate
the secondary output level of the transformers by dividing
the nominal voltage input to the PT's primary side by the
turns ratio. The result must be 120 VAC, measured
line-to-line.
Examples:
1. 4160 Volt System: Select a potential transformer with a
4160/120 ratio
35/1. Therefore, set switch SW2 for
=
35:1 ratio.
2. 3300 Volt System: Select a potential transformer with a
3600/120 ratio
30/1. Therefore, set switch SW2 for
=
30:1 ratio.
If potential transformers are not used, select a ratio of 1 :1 .
5.1.5 3 Wire/4 Wire Line-
itor either a 3-conductor or 4-conductor AC line. An example
of a 4-wire system is a case in which a transformer's secon
dary is wired in a wye configuration with the G neutral termi
nal ground brought out as the fourth wire. In this case the
G fourth wire connects with the Neutral Terminal on the IQ
Data's chassis. (See Figure 2. 1A.)
Switch
SW2, No. 8
must be set to correspond to the chosen
wiring configuration. Set this switch to the:
OFF position for a 4-wire wiring configuration
•
ON position for a 3-wire wiring configuration
•
When the OFF position is selected for the 3-wire configuration,
the Display Window does not display the 3 line-to-neutral AC
line measurements of the Operator Panel's menu. The
measurements not displayed are:
V A - N Volts RMS
•
V
Volts RMS
•
s-N
V C - N Volts RMS
•
The 10 Data can be set to meas
5.1.6 AC Line Voltage-
ure AC line voltage in one of two ways:
Some systems may
-
as listed in Table 5.8.
The IQ Data can be used to mon
Line-to-line - 3 Phase 3 Wire
•
Line-to-neutral - 3 Phase 4 Wire
•
PT RATIO SET T INGS
Ratio
PT
(1 )
1: 1
ON
2:1
OFF
4: 1
ON
OFF
5:1
20:1
ON
OFF
30:1
35: 1
ON
40:1
OFF
55: 1
ON
60:1
OFF
70:1
ON
100:1
OFF
120:1
ON
120:1
ON
(1 l
Required setting when no
Note that the settings of these potential transformers' switches
allow the IQ Data to calculate and display the original, un
reduced line voltage even though the level at the AC Line Con
nection Terminals is reduced with an external potential
transformer.
5.1.7 Display Volts-
The
3 AC line-to-neutral voltages which appear in the Display Win
dow are auto ranged to represent units of kilovolts or volts.
Shaded area designates information that
replaces or supplements applications using
the 3-phase Power Module.
21
IQ DATA
Table 5.8
Switch Settings
SW2
2
1
3
ON
ON
ON
ON
OFF
ON
OFF
ON
OFF
ON
ON
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
OFF
ON
OFF
ON
ON
OFF
ON
OFF
Any other combinations
PT
used.
3
AC line-to-line voltages and the
4
ON
ON
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
OFF
OFF
OFF
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