Voltage Circuits
All Cooper Power Systems VR-32 regulators have provi-
sions for operation at system voltages lower than the
nameplate rating, as listed in Tables 11 and 12 (see
Appendix). This is accomplished by providing taps on the
control winding or PT. The taps are brought to a terminal
board located on top of the tap-changer assembly, under
oil, and are marked
E
,
E
2
, etc. (See Figure 16.) The con-
nections are made with push-on terminals and are easily
accessed through the hand hole.
If an additional voltage transformer is required for a Reverse
Power Flow application or indication of the unregulated
voltage supply, the "
P
" taps are located on the voltage
transformer itself or on the tap-changer terminal board.
The tapped potential winding cannot always provide
adjustment of the voltage fine enough for control or motor
use. A tapped autotransformer is therefore used for fine
voltage adjustment. This transformer, the Ratio Correcting
Transformer (
RCT
), has input taps at 104, 110, 115, 120,
127, and 133 V. The output tap to the control and motor
is set as 120 V.
RCT
is located on the control back panel
(see Figure 11).
To operate a regulator on a system other than its rating,
the appropriate selection must be made for the internal tap
and
RCT
tap (and
RCT
2
if provided) and the control must
be programmed properly at Function Code 43 (System
Line Voltage) and Function Code 44 (Overall PT Ratio). The
nameplate provides these values for common system volt-
ages (see Figures 9 and 10).
The internal voltage supply is brought from the tap-changer
terminal board to the junction box terminal board through
the control cable, into the enclosure, terminating at the
knife switch labeled
V
(and
V
2
,
V
6
if provided). Opening
this knife switch provides a visible means of removing all
power to the control and motor circuits. From the knife
switch, the voltage is ratio corrected by
RCT
as previ-
ously described. The motor circuit is routed directly to the
control front panel and the sensing potential is brought
back to the top terminal strip through a series of removable
jumpers and then to the front panel. This scheme allows for
the complete interchangeability with all the prior CL-series
controls and accompanying accessories.
Most voltage regulators are installed in circuits with well-
defined power flow from source to load. However, some
circuits have interconnections or loops in which the direc-
tion of power flow through the regulator may change. For
optimum utility system performance, a regulator installed
on such a circuit should have the capability of detecting
reverse power flow and of sensing and controlling the
voltage, regardless of the power flow direction. The CL-6
control has full reverse power capabilities.
Refer to
Service Information S225-11-1 Voltage
Regulators, CL-6 Series Control Installation, Operation,
and Maintenance Instructions
for more information on the
CL-6 control, reverse power operation, and source-side
voltage calculation.
On the front panel, the three potentials (
V
s
, sensing volt-
age;
V
7
, differential voltage;
V
m
, motor voltage) are all
brought directly to the power switch. Without an optional
source-side supply, the
V
7
terminal is connected to the
V
s
terminal on the control back panel and the control software
then recognizes that the
V
7
voltage is not present.)
The power switch has three positions: internal, off, and
external. The internal position powers the control and
motor from the regulator sensing winding, and the external
position permits an external supply for the same purpose.
When the power switch is in the external position, the
internal supply is disconnected to prevent accidentally
energizing the high-voltage winding and bushings. The
external-source terminals are prominently located adjacent
to the voltmeter test terminals.
VR-32 Voltage Regulator Installation, Operation, and Maintenance Instructions
8
Figure 16 .
Internal tap terminals .
E Taps
