4
SECTION 3
CONTROLS ADJUSTMENT
PROCEDURES AND
VOLTAGE REGULATOR
OPERATING
PROCEDURES
SAFETY PRECAUTIONS
The precautions described in Section 2 must be
followed when inspecting, making internal adjust-
ments, or making repairs to this equipment.
VOLTAGE REGULATING SYSTEM CONTROLS
The voltage regulating system includes the external
voltage adjust rheostat for adjustment of generator
output voltage, a voltage range potentiometer R3
located on the circuit board that extends either the
minimum voltage limit or maximum voltage of the
voltage adjust circuit, and a stability control potenti-
ometer R7 located on the circuit board that provides
means of increasing or decreasing a stabilizing signal
to attain optimum response and system stability.
Adjustment procedures are as described in the
paragraphs that follow.
A. Voltage Adjustment.
This adjustment is made
while the generator is running at rated frequency and
while no-load is applied. Turning the externally
mounted voltage adjust rheostat clockwise increases
generator output voltage. When it is turned in a
counterclockwise direction, a decrease in generator
output voltage should occur. Voltage is measured
during the adjustment procedure by observing the
generator voltmeter.
B. Voltage Range Adjustment.
This adjustment
extends either the minimum voltage limit or the
maximum voltage limit of the external voltage adjust
rheostat. It is normally factory set at about 1/2 its
maximum travel. To limit maximum voltage adjust as
follows:
NOTE: In applications that include overvoltage
protection circuitry the maximum voltage setting
should be lower than the overvoltage trip setting.
1
. Operate generator at rated frequency with no-load
applied. Turn the external voltage adjust to its maxi-
mum clockwise position.
NOTE:
Turning R3 clockwise raises the maximum
voltage while turning it counterclockwise decreases
the maximum voltage.
2.
Measure generator voltage using the generator
outputvoltage. If voltage is not the required maximum,
turnpotentiometer R3 in the appropriate direction until
3' voltmeter indicates output voltage is the required
maximum. This is the final adjustment of R3.
3.
Turn external voltage adjust counterclockwise to
position where output voltage decreases to rated
value.
C. Stability Adjustment R7.
This control is located
on the regulator printed circuit board. Adjust R7 only if
during operation oscillating voltage or slow response
occurs.
1. Slow Response.
Turn R7 clockwise to position
where response is satisfactory. Test with load applied
and also with no-load applied. If oscillating voltage
occurs turn R7 clockwise past the point where
oscillation stops.
2. Voltage Oscillating.
Turn R7 clockwise past the
position where oscillations stop. Test no-load and with
load applied.
NOTE:
Slow response, loss of sensitivity and poor
regulation could occur if R7 is turned too far counter-
clockwise.
OPERATING PROCEDURES
The instructions that follow describe the procedures
to be followed during initial operation and during
subsequent operation of the unit. The preceding
chapters as well as the following procedures should
be reviewed and understood before system operation
is attempted. The system operator should also locate
all controls and adjustments pertinent to system
operation before attempting to operate the equip-
ment.
A. Initial operation
1.
Open output circuit breaker or contactor. Initial
start-up should be made with no-load.
2.
In applications where system includes overvoltage
devices or a field circuit breaker, make certain the
field circuit breaker and overvoltage circuit is not
tripped open.
3.
In applications where system includes both auto-
matic voltage control, and manual voltage control set
