CAUTION
!
The voltage regulator dc output (terminals
F+ and F-) must never be opened during
operation. To do so will produce inductive
arcing that can possibly destroy the exciter
and/or the voltage regulator. Therefore,
never
place the voltage shutdown switch in
the exciter field circuit.
CAUTION
!
Do not attempt to flash the machine when
it is rotating.
the regulator but can be ordered separately
from the Basler Electric Company.
The KR Voltage Regulators contain filter
capacitors that are internally connected
between terminal 3 and the chassis and
between terminal 4 and the chassis. Each
capacitor is rated at 370 Vac. When using
these regulators with generators whose output
is above 370 Vac, ensure that the voltage
between terminal 3 and ground and terminal 4
and ground does not exceed 370 Vac. The
voltage across the regulator's filter capacitors
can exceed 370 Vac on an ungrounded
generating system when the line-to-line voltage
exceeds 370 Vac.
Example (Figure 6): On a 480 Vac generating
system with an ungrounded neutral lead and
regulator chassis, if the KR7FFX regulator input
power (terminals 3 and 4) is obtained line-to-
neutral (277 Vac), and then a ground occurs on
one of the other two generator lines, 480 Vac
will be applied across one of the voltage
regulator filter capacitors.
On this same system with the same conditions,
but with the regulator connected phase-to-
phase (T7 and T9) at the generator's Wye con-
nection tie point (240 Vac) the voltage across
the regulator's filter capacitors would have been
reduced to 366 Vac.
If the line-to-line voltage of the generating
system is reduced to 416 Vac, the voltage
across the regulator's filter capacitors is
reduced to 318 Vac.
The power input leads are EMI filtered. In most
applications, securing the regulator with a good
metal-to-metal bond ensures a reduction in
interference to acceptable limits. As in all
interference reduction situations, it is necessary
to maintain a good electrical connection
between the filter ground and the system
ground. A good electrical power ground is
not
necessarily a good interference ground.
Ground leads should be as short as possible,
preferably of a copper braid whose width is 1/5
of the length. For applications involving radio
reception, additional improvement can be
noticed by connecting the system to earth
ground. This is because radio reception takes
place between an antenna and earth ground.
Grounding the system to earth ground simply
makes all grounds common.
Output Power (Terminals F+ and F-)
The dc resistance of the exciter field winding
must be at least the minimum value specified in
the
Electrical Specifications
. If the field
resistance is less than this value, a series
resistor is required to increase the field
resistance. This additional resistance is
required to limit the regulator field current
forcing because excessive current may damage
the regulator semiconductors. This resistance
must not be of such a value as to restrict the
excitation at full load.
Because the regulator output leads are not
connected to any part of the system except the
generator field, they are not filtered. Since EMI
is present on these leads, it may be necessary
to observe precautions with regard to the lead
installation. Optimum results will be obtained
when the field leads are kept as short as
possible and shielded. Effective shielding can
be achieved by routing both leads through a
standard 0.5 inch diameter conduit. Not more
than one or two feet of the field leads should be
unshielded. If the regulator is installed on the
generator frame, it is possible to achieve
satisfactory results with short, unshielded
leads.
External Voltage Adjust Rheostat
The voltage adjust rheostat (Terminals 6 and 7)
is furnished with the voltage regulator for
remote mounting and wiring. It should be 175
ohms and 2 watts minimum.
MOUNTING
The Voltage Regulator may be mounted in any
position. However, it should be vertically
mounted to obtain optimum cooling. The Reg-
ulator can be mounted in any location where
the ambient temperature does not exceed the
operational limits. Due to its rugged construc-
tion, the Regulator can be mounted directly on
the generator. Mounting hardware should be
selected based upon the vibration and shock
expected to be encountered during shipping/
transport and normal operation. Refer to Figure
7 for the outline drawing of the unit which pro-
vides overall and mounting dimensions.
ACCESSORY ITEMS
Voltage Shutdown Switch
The system can be equipped with a switch to
allow the removal of the excitation in case of an
emergency or when the generator prime mover
must be operated at reduced speed. This
switch
must always
be placed in the input
power line that is connected to the regulator at
terminals 3 and 4.
Parallel Operation
An APM 300 Paralleling Module is available
for use with the voltage regulator and will
provide for the parallel operation of two or
more generators.
Manual Voltage Control
A Manual Voltage Control is available for use
with the voltage regulator to provide a manual
backup that is independent of the voltage
regulator.
Excitation Support System
In brushless exciter applications, no source of
power is available for field forcing during short
circuit and large motor starting conditions. The
addition of an Excitation Support System will
prevent the collapse of excitation by providing
constant voltage to the regulator for all load
conditions and short circuits.
OPERATION
This section contains operation procedures.
Before operating, ensure that the regulator is
connected into the system as shown on the
interconnection diagram (Figure 5). Even
momentary operation with an incorrect
connection can damage the regulator or other
control equipment.
Field Flashing
When the Voltage Regulator is operated with
the generator for the first time, the polarity of
residual magnetism may not be correct or of
sufficient magnitude. If the generator does not
build up after start-up, check for 6 volts or more
residual at the regulator terminals TB1-3 and
TB1-4. If the voltage is below 6 volts, shut
down the prime mover and proceed as follows:
1. With the prime mover at rest, connect a
limiting resistor of 25 to 30 ohms in series with
the field (terminals F+ and F-).
2. Observe polarity and apply a dc source
(non-grounded) of not more than 12 Vdc, to the
series circuit of the field and resistor.
3. Allow approximately 3 seconds before
removing the dc source.
4. With the voltage regulator power input
disconnected (terminals 3 and 4), start the
prime mover and measure the voltage at the
generator terminals. If the generator output is
less than 6 volts, repeat steps 1 through 3. If
the voltage is greater than 6 volts, voltage
build-up should occur. Stop the prime mover
and reconnect the regulator input power.
Preliminary Operation
Verify that all wiring is properly and securely
connected (Refer to Figure 5).
System Checkout
Perform the following steps to ensure the
proper operation of the regulator initial
operation.
Step 1. Start the prime mover and bring up to
rated speed. If a voltage shutdown switch is
used, close the switch to apply excitation.
When this switch is not used, generator voltage
will build-up automatically.
Step 2. Verify the generator output voltage.
Note that any of the following conditions may
occur:
(a)
Overvoltage
. If this condition occurs,
open the shutdown switch and stop the prime
mover. determine the cause of the overvoltage.
If necessary refer to the troubleshooting chart.
(b)
No Voltage Build-up
. If this condition
occurs, field flashing may be required.
(c)
Undervoltage
. If this condition occurs,
adjust the External Voltage Adjust Rheostat. If
not corrected, refer to the troubleshooting chart.
(d)
Voltage Builds Up and Then Collapses
.
If this condition occurs, stop the prime mover
and determine the cause by referring to the
troubleshooting chart.
(e)
Oscillating Voltage
. If this condition
occurs, rotate the Stability Adjustment Poten-
tiometer (R15) to correct. If the voltage
continues to oscillate and the Stability
Adjustment (R15) has no effect, refer to the
troubleshooting chart.
WARNING
!
To eliminate any electrical shock hazard,
it is imperative that the regulator chassis
(filter ground) be connected to the system
power ground. This is because the filter
capacitors are connected between the line
and the regulator case.
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