Guardian 4721, Руководство по ремонту

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PART 5
OPERATIONAL ANALYSIS
During the engine start-up and run, +12 volts DC is
applied to the control module via the red (+ positive)
and black (- negative) wires. The voltage from the
main engine control latch/crank PCB Wire 14 (run cir-
cuit) powers up the control module for governor sys-
tem operation. The control module receives a speed
“sensing” signal from AC output frequency via the two
(2) blue wires.
The control module sends variable signals to the
stepper motor via the orange, yellow, brown and
black wires to position the stepper motor and throttle
linkage to obtain a steady 50 or 60 Hz. (selectable on
the control module frequency switch)
SET-UP AND ROD LENGTH ADJUSTMENT
PROCEDURE
STEPPER MOTOR/THROTTLE LINKAGE
Determine which direction the stepper motor must
rotate to open the throttle to “full fuel”. Adjust the rod
length so when the throttle is wide open, the stepper
motor is at it’s full rotation, then tighten the jam nuts.
Ensure linkage moves freely and does not bind in any
way.
CONTROL MODULE POTS AND SWITCHES
The following is description of the adjustment proce-
dure for the electronic governor control module and
stepper motor. (See Figure 2)
POT SETTINGS:
Set GAIN, DROOP, and STABILITY pots to midpoint.
SWITCH SETTINGS:
Set frequency switch to the OFF position (60 Hz).
Frequency switch set to ON is for 50 Hz operation.
SET DIRECTION SWITCH:
The lever arm opens the throttle by rotating in the
counterclockwise direction. The direction switch
should be set in the OFF position.
When the switches and pots are set correctly, start
the engine. Adjust the gain pot if necessary to stabi-
lize engine speed.
• Apply a 25-50% load to system. If system is unsta-
ble, reduce gain until it stabilizes.
• Adjust droop pot so that the engine speed recovers
to the pre-selected speed. (50 or 60 Hz based on
unit).
• Observe performance of system when loads are
applied and removed.
• Increasing stability will decrease recovery time, but
may result in damped oscillations (decreasing hertz
around preset speed). Decreasing stability will soft-
en the recovery and reduce the transient hertz.
Frequency and direction switches are integrated only
at engine start. Changing switch settings while engine
is running will have no effect until the engine is
stopped and restarted.
VOLTAGE REGULATOR ADJUSTMENT
GENERAL:
For additional information on the prepackaged AC
voltage regulator, see “The Excitation Circuit” in
Section 2.1 of this manual.
Before adjusting the voltage regulator for correct AC
voltage output, make sure engine governed speed is
correct.
ADJUSTMENT PROCEDURE:
1. Connect an accurate AC voltmeter and frequency meter
across the generator’s AC output leads. Readings of line-
to-line voltage may be used.
2. Start the engine, let it stabilize and warm up at no-load.
3. Check the AC frequency reading. Frequency should be
as close as possible to 60 Hertz at no-load. Adjust the
engine governor, if necessary.
4. With engine running at correct speed (frequency), slowly
turn the slotted potentiometer on the regulator to obtain
the proper AC voltage as follows:
a. For units rated 120/240 volts AC, the no-load
line-to-line voltage should be as close as possi-
ble to
242 volts (240-244 volts).
b. For units rated 120/208 volts AC, the no-load
line-to-line voltage should be as close as possi-
ble to 210 volts (208-212 volts).
NOTE: The no-load voltage is generally propor-
tional to AC frequency. For units rated 240 volts,
the no-load (line-to-line) voltage at 62 Hertz will be
approximately 248 volts. For units rated 120/208
volts, the no-load (line-to-line) voltage will be
about 215 volts.
Figure 5. Voltage Regulator
VOLTAGE ADJUST
POTENTIOMETER
Page 100
OPERATIONAL TESTS
AND ADJUSTMENTS
SECTION 5.2
ADJUSTMENTS — LIQUID COOLED UNITS