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VR-32 and EVER-Tap™ Voltage Regulator
Current circuit
All Eaton voltage regulators are designed with an internal
current transformer (CT) (see Figure 19) to provide a current
source for the line-drop compensation calculations, power
flow direction determination and for metering functions.
Table 4 provides the application information for the various
CTs used on Eaton regulators. These CTs provide 200 mA
output for the rated CT primary current.
Figure 19 . Internal bushing-mounted current transformer
The current developed by the CT is brought through the
control cable and junction box, into the control box and
terminates at the knife switch labeled C. Closing the knife
switch provides a visible means of shorting the CT, thus
allowing the operator to work safely on the current circuitry.
For additional safety measures, the V1, V2, V6, and V8
knife switches should also be opened. For all regulators with
the quick-disconnect connector (Figure 1), an automatic
solid-state CT shorting device is located in the junction box.
This solid-state device will automatically short the CT when
the cable is disconnected.
At this knife switch, one side of the CT is connected to
the equipment ground and is also routed to the front panel
for termination on the circuit board. The "high" side of the
current circuit is brought to the top terminal board through
two removable jumpers and then to the front panel for
connection to the circuit board. Once this current signal is
delivered to the circuit board, it is transformed into a voltage
signal and converted into a digital format for processing.
18
InstallatIon, operatIon, and MaIntenance InstructIons MN225008EN June 2020
Table 4 . Current transformer applications (50 & 60 Hz)
Regulator Current Ratings
50
75
100
150
167, 200
219, 231, 250
289, 300
328, 334, 347, 400
418, 438, 463, 500, 502
548, 578, 604, 656, 668
833, 875, 1000, 1093
1332, 1503, 1665
2800
Motor circuit
The motor circuit power is brought from the 6 A fuse to
the circuit board through a set of back-to-back diodes to the
CONTROL FUNCTION switch. When this switch is set for
automatic operation, motor power is applied to the relays.
An appropriate relay closure then applies this power to
the tap-changer motor, after first passing through the limit
switch contacts in the position indicator. When the switch
is set for manual operation, the power is transferred to
the momentary toggle switch labeled RAISE/LOWER. By
actuating this switch in one direction or the other, power
is applied through the limit switch contacts, directly to the
tap-changer motor, completely bypassing the control circuit
board. This enables operation of the tap-changer in most
circumstances, even if the control cannot be powered up
fully.
Also included as a part of the motor circuit is an alternate
feed to the motor called the holding switch circuit. Located
on the tap-changer are switches which operate off of the
tap-changing mechanism. Motor rotation causes switch
closure (one direction or the other) and establishes a
complete circuit for motor current until the rotation is
complete and the cam drops out. During the time the
holding switch is closed, motor current is monitored by
way of an input on the control circuit board that permits
the control to detect that a tap change is in process. The
microprocessor uses this information in its decision-making
process, as described under Control Operating Modes in
Service Information MN225003EN (225-70-1), CL-7 Voltage
Regulator Control Installation, Operation, and Maintenance
Instructions.
Two other circuits that share the 6 A motor source are
the drag-hand reset and neutral light circuits. The drag-
hand reset function is accomplished simply by operating
a momentary membrane switch, which applies power to
the reset solenoid in the position indicator. The neutral
light is energized from a neutral light switch located on the
tap-changer when in the neutral tap position.
CT Primary Current
50
75
100
150
200
250
300
400
500
600
1000
1600
3000
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