Operating sequence
When the tap-changer is in the neutral position and the
control calls for a tap change, the following events occur.
1. The motor is energized and rotor begins to move.
2. The motor drives the Geneva drive.
3. The pin and roller on the Geneva drive gear enters a
slot on the main Geneva/contact drive assembly and
the main Geneva/contact drive assembly begins to
index.
4. The holding switch closes to ensure the tap change will
go to completion. The control opens the initial circuit.
The motor is energized only by way of the holding
switch.
5. The reversing switch pin on the main Geneva/contact
drive assembly begins to drive the reversing switch
arm.
6. One of the two main interrupting movable contacts
slides out of engagement with the neutral stationary
contact and interrupts the circuit through that branch.
7. The reversing switch arm rotates, which causes the
reversing switch contacts to pivot. A bridge between
the neutral contact and a stationary contact connected
to one end of the series winding is thus established.
No arcing occurs across the reversing switch contacts.
When the reversing arm rotates, a logic switch is
triggered.
8. The main interrupting contacts slide over and onto
the number one stationary contact, making a bridging
position from contact
N
to contact
1
by way of the
reactor.
9. The pin on the Geneva drive gear exits the main
Geneva/contact drive assembly slot. The main Geneva/
contact drive assembly stops moving and is rotationally
locked.
10. The holding switch opens and the motor is
de-energized.
11. The magnetic rotor of the AC synchronous motor or
the brake used with the AC induction motor stops the
Geneva drive gear at mid-travel.
12. The elapsed time from step 1 to step 11 is
approximately 250 ms.
13. If the control issues another signal to index in the same
direction, the same sequence is repeated except the
reversing switch is not actuated. The reversing switch
does not move until the tap-changer is reversed and
stepped the opposite direction back to neutral.
14. If the tap-changer is switching from position 15 to
position 16, a normally closed limit switch is triggered
that is connected in parallel with the logic switch. Both
the limit switch and the logic switch open up, so that
the control cannot make a tap change past position 16.
EVER-Tap™ voltage regulators
The EVER-Tap voltage regulator utilizes a VACUTAP®
RMV-SVR-I-2000 tap changer from Maschinenfabrik
Reinhausen (see
). This tap changer is rated for an
industry-leading 1,000,000 operations before maintenance
is required. A first inspection of the tap changer is
recommended after 500,000 operations. Inherent to the
vacuum interrupting design of this tap changer is that
material and gas byproducts from tapping operations do
not accumulate in the dielectric fluid. This preserves a clean
operating environment inside the voltage regulator tank,
prolongs tap changer contact and coil winding life, and
significantly extends maintenance intervals.
Figure 23 . EVER-Tap voltage regulator’s RMV-SVR-I-2000
tap changer
EVER-Tap® tap-changer and Motor drive unit
The tap changer comprises four switch modules linked
together through a common mechanism to synchronize the
modules’ operations. The tap selector module and reversing
switch module share functional similarities with the Quik-
Drive™ tap changers with the exception that arc-resistant
materials are not required on the movable or stationary tap
selector contacts. The by-pass switch module (sometimes
referred to as a “diverter switch”) works in coordination
with the vacuum interrupter module to interrupt current
to the appropriate tap selector contact prior to switching.
Arcing is contained within the vacuum interrupter, thus
preserving the dielectric fluid of the voltage regulator.
ETMD-A motor drive unit
The tap changer is operated by a motor drive unit comprised
of a motor, gearbox, position indicator linkage, and micro
switches for feedback to the voltage regulator control. Some
motor drive units require the control to be equipped with
an auxiliary actuator board to manage start, stop, and tap
21
VR-32 and EVER-Tap™ Voltage Regulator
InstallatIon, operatIon, and MaIntenance InstructIons
MN225008EN June 2020
