S&C Instruction Sheet 1022-510
7
Installing the Current Sensor (var only)
The IntelliCap with Var control uses the phase-angle
relationship between the voltage waveform of the 120-Vac
control power source and the current waveform from the
current sensor. Calculations will be incorrect if the control-
power source is not connected to the feeder being monitored
for current.
Other factors that may also affect accuracy:
• To achieve the most accurate var-calculation results,
power the control with a dedicated potential transformer
(PT) that has at least one leg connected to the same phase
as the current sensor.
• The PT supplying control power to the control may be
connected phase to phase or phase to ground. Either
connection can be configured in the setup software.
• When the control is powered from an adjacent secondary,
the phase angle may be affected slightly. The calculated
var level may also be changed by a few percentage points,
depending on the secondary loading and its associated
voltage reduction. With this wiring configuration, voltage-
override logic will not have effective control of the primary
feeder voltage.
• Because calculations are based on single-phase current,
balanced three-phase currents or loads will produce the
best results. Current measurements at the time of instal-
lation may help to decide the best phase to monitor if the
feeder is significantly unbalanced.
• Install the current sensor on the source side of the
capacitor bank connection. See Figure 1 on page 8. The
source side is the side nearest the substation during
normal operation. The control will then measure the effect
of the capacitor bank on power factor when the bank is
switched in.
• Signal polarity reversal can be configured in the setup
software.
• Ground the sensor base at the top of the pole.
• With S&C and Lindsey line-post current Sensors, the signal
wires are shielded, and the shield must be grounded at the
IntelliCap control for safety.
• We recommend that a Lindsey current sensor be installed
with a permanent current-sensor choke. This eliminates
the need for field calibration and ensures more accurate
results. The S&C current sensor does not require a choke.
Installation
Summary of Contents for IntelliCap
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