MTD 464 Betriebsanleitung PDF herunterladen (Seite 212)

(1)

(2)

(3)

(4)

(5)

(6)

If the FL-NL or NL - FL transient exceeds 1-1/2 percent of rated speed and/or does not

reestablish stable engine operating conditions within one second, realign the control unit in

accordance with paragraph 3-64j. Also follow this procedure if the engine speed hunts. If the set

cannot be stabilized, check sockets A and B of plug P-21 (figure 3-97) for 24 Vdc (A is positive).

If the engine speed increases to above nominal operating speed, check sockets A and B of P-17

(figure 3–97) for 120 Vac. If it is missing, troubleshoot the generator set wiring. Refer to schematic

and troubleshooting diagram plates located on inside of left and right engine compartment doors

(figure 3-97). If it is present, check the resistance of the frequency adjusting circuit consisting of R4

(250 ohms) rheostat R1 frequency adjust (500 ohms) and R6 (250 ohms) fixed resistor. Measure the

total circuit resistance across N and T of harness plug PI 7 (figure 3-97). The circuit resistance

should be 1000 ohms (5 percent tolerance). After testing for correct total resistance, test the

operation of the frequency adjust rheostat by connecting an ohmmeter across pins M and T and

revolving the frequency adjust rheostat through its entire travel. The resistance should vary from 750

ohms to 250 ohms. Repeat this procedure using the ohmmeter across pins M and N of the harness

plug. If the problem persists, check sockets A and B of plug P-21 (figure 3-97) for 24 Vdc (A is

positive).

If the engine speed remains below the nominal operating speed, adjust RI. If there is no

improvement, check the resistance of the frequency adjust circuit. Disconnect P–17 and check the

resistance of the frequency adjust circuit consisting of R4 (250 ohms) fixed resistor, RI frequency

adjust rheostat (500 ohms) and R5 (250 ohms, 5 percent) fixed resistor. Measure the total circuit

resistance across N and T of harness plug P-17. The circuit resistance should be 1000 ohms (5

percent tolerance). After testing for correct total resistance, test the operation of the frequency adjust

potentiometer by connecting an ohmmeter across pins M and T and revolving the travel. The

resistance should vary from 750 ohms to 250 ohms. Repeat this procedure using the ohmmeter

across pins M and N of the harness plug. Disconnect actuator electrical connector before making this

measurement. Push actuator piston all the way down and adjust engine speed with manual throttle.

If this value resistance is measured, check sockets A and Bat plug P–21 for 24 Vdc (A is positive).

If the set is operating at a constant load and voltage and during an eight–hour period the change in

ambient temperature does not exceed 60°F, the set frequency should not drift beyond 1/2 of one

percent of rated frequency. The above requirement assumes that the set temperatures were

stabilized at the initial and final ambient temperatures.

NOTE

If the drift in paragraph (4) is excessive, realign the control unit following the procedure

outlined in paragraph 3-64j.

At constant ambient temperature, constant load, constant voltage and constant barometric pressure,

the set frequency should remain within a bandwidth of 1 percent of rated frequency for a period of 4

hours. If this bandwidth has been exceeded, realign the control unit in accordance with paragraph

3-64j.

If the preceding solutions to the specific problem do not resolve the problems, replace and repair the

control unit, actuator (paragraph 3-43) or load measuring unit (paragraph 3–63) as required.

c. Removal.

(1) Tag and disconnect electrical connectors to governor control unit.

(2) Remove nuts (1, figure 3-68), Iockwashers (2), nuts (3), Iockwashers (4) and bracket (5), threaded

rod (6) and lift governor control unit from mounting bracket.

3-158

ARMY TM 9-6115-464-34

AIR FORCE 35C2-3-445-2

NAVY NAVFAC P-8-624-34

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