5. Objetivos particulares.
12.5 Modelaje Molecular.
12.5.5 Análisis Conformacional Sistemático.
DISCUSSION:
The generator AC frequency is proportional to the operating speed of the rotor. The 2-pole rotor will sup- ply a 60 Hertz AC frequency at 3600 rpm. The unit’s AC output voltage is proportional to the AC frequency. For example, a unit rated 240 volts (line-to-line) will supply that rated voltage (plus or minus 2 percent) at a frequency of 60 Hertz. If, for any reason, the frequency should drop to 30 Hertz, the line-to-line voltage will drop to a matching voltage of 120 volts AC. Thus, if the AC voltage output is high or low and the AC frequency is correspondingly high or low, the engine speed governor may require adjustment. PROCEDURE:
1. Connect an accurate AC frequency meter across the Wires 11 and 44 terminals of the generator main line circuit breaker (see Figure 1, Section 2.4).
Part 2
2. Start the engine, let it stabilize and warm up at no-load.3. When engine has stabilized, read the frequency meter. The no-load frequency for single cylinder units should be about 62-63 Hertz. For V-Twin units, the no-load fre- quency should be about 57.5-59.5 Hertz.
RESULTS:
1. If the AC frequency is high or low, go on to Test 12 for single cylinder units, or Test 12A for V-Twin units. 2. If frequency is good, but voltage is high or low, go to Test
13.
3. If frequency and voltage are both good, tests may be discontinued.
teSt 12 – check and adjUSt enGIne
GoVernor (SInGle cylInder UnItS)
DISCUSSION:
The generator AC frequency output is directly pro- portional to the speed of the rotor. A two-pole rotor (having a single north and a single south magnetic pole) will produce an AC frequency of 60 hertz at 3600 RPM.
The generator is equipped with a “voltage over fre- quency” type AC voltage regulator. The units AC out- put voltage is generally proportional to AC frequency. A low or high governor speed will result in a corre- spondingly low or high AC frequency and voltage out- put. The governed speed must be adjusted before any attempt to adjust the voltage regulator is made.
GOVERNOR SHAFT PRIMARY ADJUST SCREW GOVERNOR CLAMP BOLT SECONDARY ADJUST SCREW
(7KW UNITS WITH DUAL GOVERNOR SPRINGS)
Figure 8. Engine Governor Adjustment Single Cylinder Engines
PROCEDURE
(6/7 kW UNITS WITH DUAL GOVERNOR SPRINGS): 1. Loosen the governor clamp bolt (Figure 8).
2. Hold the governor lever at its wide open throttle position, and rotate the governor shaft clockwise as far as it will go. Then, tighten the governor lever clamp bolt to 70 inch-pounds (8 N-m).
3. Start the generator; let it stabilize and warm up at no- load.
4. Connect a frequency meter across the generators AC output leads.
5. Turn the primary adjust screw to obtain a frequency reading of 61.5 Hz. Turn the secondary adjust screw to obtain a frequency reading of 62.5 Hz.
6. When frequency is correct at no load, check the AC volt- age reading. If voltage is incorrect, the voltage regulator may require adjustment.
RESULTS:
1. If, after adjusting the engine governor, frequency and voltage are good, tests may be discontinued.
2. If frequency is now good, but voltage is high or low, go to Test 13.
3. If engine was overspeeding, check linkage and throttle for binding. If no governor response is indicated refer to engine service manual.
4. If engine appears to run rough and results in low fre- quency, proceed to Problem 11, Section 4.3.
teSt 12a – check Stepper motor
control (V-tWIn enGIne UnItS)
PROCEDURE:
1. Remove air cleaner cover to access stepper motor. 2. Physically grab the throttle and verify the stepper motor,
linkage and throttle do not bind in any way, if any bind- ing is felt repair or replace components as needed. Some resistance should be felt as the stepper motor moves through it’s travel.
3. Physically move the throttle to the closed position by pulling the stepper motor arm towards the idle stop. See Figures 9 and 10 (for 9/10 kW units) or Figure 11 (for 13/16/18 kW Units).
a. Place the AUTO-OFF-MANUAL switch (SW1) to MANUAL and watch for stepper motor move- ment. It should move to the wide open position during cranking. Once the unit starts the stepper motor should move the throttle to a position to maintain 57.5-59.5 Hertz.
AC GENERATORS
AC GENERATORS
DiaGNostic tEsts
4. If no movement is seen in Step 3 remove the controlpanel cover. Verify the six pin connector on the printed circuit board is seated properly, remove the connector and then replace it and test again. Verify the switches are correctly set.
5. If problem continues remove six pin connector from printed circuit board. Set Volt meter to measure ohms. Carefully measure from the end of the six pin harness as follows:
note: press down with the meter leads on the connectors exposed terminals, do not probe into the connector.
a. Connect one meter lead to Red, connect the remaining test lead to Orange, approximately 10 ohms should be measured.
b. Connect one meter lead to Red, connect the remaining test lead to Yellow, approximately 10 ohms should be measured.
STEPPER MOTOR
PULL ARM THIS DIRECTION TO CLOSE THROTTLE
Figure 9. Throttle Positions 9/10 kW Units
STEPPER MOTOR
STEPPER MOTOR ARM PULL ARM THIS
DIRECTION TO CLOSE THROTTLE
Figure 10. Throttle Positions 9/10 kW Units
c. Connect one meter lead to Red, connect the remaining test lead to Brown, approximately 10 ohms should be measured.
d. Connect one meter lead to Red, connect the remaining test lead to Black, approximately 10 ohms should be measured.
e. Connect one meter lead to Red, connect the remaining test to the stepper motor case. No resistance should be measured INFINITY or Open.
STEPPER MOTOR
STEPPER MOTOR ARM
PULL ARM THIS DIRECTION TO CLOSE THROTTLE
Figure 11. Throttle Positions 13/16 kW Units
RED EMPTY YELLOW BROWN ORANGE BLACK
Figure 12. Six Pin Connector Wire Colors
RESULTS:
1. If the stepper motor fails any part of Step 5 replace the stepper motor.
2. If the stepper motor passes all steps replace the Printed Circuit Board.