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Figure 3-66. Load Measuring Unit Component Test and Replacement Diagram
Removal. - TM-9-6115-464-34_212

TM-9-6115-464-34 Generator Set Diesel Engine Driven Tactical Skid Mtd 15 Kw 3 Phase 4 Wire 120/208 and 240/416 Volts Manual
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(10) (11) (12) ARMY   TM   9-6115-464-34 AIR  FORCE  TO  35C2-3-445-2 NAVY  NAVFAC  P-8-624-34 If adjustment does not give the proper relationship or if relationship varies outside of acceptability limits at any point, replace load measuring unit load resistor. Deactivate power source and remove load measuring unit from test circuit. Install load measuring unit cover (figure 3-64). e. Assembly. (1) Position base (27, figure 3-84), to install diode (26), transformer (25), insulation washer (24), spacer sleeve (23), flatwasher (22), Iockwasher (21) and screw (20). (2)  Install  screw  (19),  insulating  washer  (18),  load  resistor  (17),  insulating  washer,  flatwasher  (15), Iockwasher  (14)  and  nut  (13). (3) Install connector bracket (12), screw (11), flatwasher (10), lockwasher (9), and nut (8). (4)  Install  connector  (7),  Iockwasher  (6),  and  screws  (5). (5) Install cover (4), with flatwasher (3), Iockwasher (2) and nut (1). f. Installation. Refer to the Operator and Unit Maintenance Manual for load measuring unit installation instructions. 3-64.  ELECTRO-HYDRAULIC  GOVERNOR  CONTROL  UNIT. a.  General. (1) (2) (3) (4) (5) (6) The electro-hydraulic governing system is a speed (frequency) sensing system used to maintain prime mover speed constant and therefore generator output frequency, during periods of unchanging load and when load additions or deletions occur. The system consists of a control unit, load measuring unit and hydraulic throttle actuating unit. The control unit inputs are the generator output voltage, and a dc voltage (O-9.8 Vdc) proportional to the generator load, supplied by the load measuring unit. The generator voltage input is applied to a frequency sensing network and reference voltage network. The differential output of these two networks determines the control current of two magnetic amplifiers whose outputs drive separate coils of the hydraulic actuators pilot valve. The actuator pilot valve positions the actuator power piston which is connected to the input arm of the fuel injection pump. The actuators hydraulic system is comprised of a reservoir, engine driven pump (300-320 psi, 2 gpm), cooler and filter. Any deviation of engine speed, reflected as a change in frequency at the input of the governor, produces a change in the magnitude and direction of magnetic amplifier control field current. This change in control field current will increase the strength of one coil of the pilot valve while decreasing the strength of the other. The resultant difference repositions the pilot valve in turn repositioning the power piston which changes the output of the fuel injection pump, changing engine speed and consequently restoring generator frequency to its nominal value. The load measuring units (LMU) input to the governor control provides for automatic load sharing when two or more sets are operated in parallel. Each set is equipped with an LMU. If the load added to the system is not equally divided, the LMU inputs to their respective governors will differ. The resulting difference acting through additional windings of each sets governor (which are connected in parallel) will reposition each sets actuator power piston such that fuel flow in the more lightly loaded set is increased. Since the power input of each prime mover has been readjusted, equal division of true power (Kw) occurs with no deviation in frequency of any set. b. MaIfunction. The following procedures are to be performed in the generator set unless otherwise specified. 3-157







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