MEP-003A 10 KW ONAN DIESEL GENERATOR

1-9.
The
Set.
DESCRIPTION OF GENERATOR SET.
MEP-003A is a 10 kilowatt, 60 Hertz Generator
The MEP-112A is a 10 kilowatt, 400 Hertz Generator used
primarily for operating control and excitation
and (2) the ac output system to supply power to the
load.
Both consist of a revolving field alternator
powered by an air cooled diesel engine. 
These sets are not designed for parallel
operation.
a. Engine.
(1) The engine powering this Generator Set is a
4 cylinder, 4 cycle air cooled engine, with a 140 cubic
inch (cu. in.) displacement. A mechanical governor
keeps engine speed at 1800 revolutions per minute
(RPM) under rated load conditions for the MEP-003A
and at 2000 RPM for the MEP-112A.
(2) Fuel is supplied either from this units self-contained
fuel tank or, by using an adapter, directly
from a 55 gallon drum or other source. The fuel is
filtered by two cartridge type fuel filters and a single
fuel strainer, Two electric, self-priming fuel pumps
pump fuel to the fuel injection pump which delivers
the fuel at high pressure to fuel injection nozzles in
the cylinder head. When auxiliary source. of fuel is
used, three electric fuel pumps are used.
(3) Two 12 volt wet cell batteries in series
supply power for a 24 volt electric starter and for
glow plugs, located in the cylinder head, and two air
heaters located in the intake manifold, used for cold
weather starting. An alternator located beneath the
blower wheel and completely separate from the m ain
alternator automatically recharges these batteries
when the engine is operating.
b. Generator.
The generator on the MEP-O03A is a four pole, revolving
field type. The generator on the MEP-112A
is a 24 pole, revolving field type, Alternating current,
supplied by the exciter assembly, is rectified and
used to create the revolving field.
A solid-state voltage regulator assembly automatically
adjusts this current to obtain a constant
(±3%) voltage in the main stator (output) windings.
c. Controls.
All operator controls and indicator gauges necessary
for running the engine Generator Set are located on
the control panel. In addition, an oil pressure gage
is located on the engine and a fuel level gage is
located on the fuel tank. The speed control is located
below the control panel.
Controls for selecting output voltage are located on
the output control box.
d. Generator Set Electrical System (see schematic
figure 1-7).
(1) General. The generator sets electrical system
consists of two distinct systems (1) the dc system
The dc source consists of a 24 volt battery set (BT1
and BT2) that is kept charged by a battery charging
alternator (G2) and voltage regulator rectifier assembly
(A5). Fuse (F1) protects the alternator from
overload. Circuit breaker (CB2) protects the battery
charging system from overload. Slave receptacle (J15)
permits an alternate external supply to be connected
to the battery circuit.
(2) Operation, Placing MASTER SWITCH (S1) into the
PREHEAT position, the preheat relay K2 is activated to
energize the heater elements (HR1 and HR2) and the engine
glow plugs (HR3, HR4, HR5, and HR6).
Placing the MASTER SWITCH in the PRIME-RUNAUXILIARY
position activates the fuel pumps E2 and
E3 as well as the auxiliary fuel pump El. If the fuel
level is down, the fuel level switch S3 will be closed
and the auxiliary fuel solenoid will actuate permitting
fuel to be pumped into the tank.
Placing the MASTER SWITCH (S1) into the PRIME/RUN
position maintains power to the main fuel pumps
but deactivates the auxiliary fuel pump.
(a) Start. Placing the MASTER SWITCH (Sl)
into the start position maintains the fuel pump circuits
and the preheat circuits to the glow plugs (HR3,
HR4, HR5 and HR6) as well as to energize the governor
solenoid (K5) and start relay (K1). The crank relay
(K3) is energized, in turn energizing the start
solenoid (K6) and activating the starter (B1). The
governor brings the engine to speed, building up oil
pressure and closing oil pressure switch (S5). The
exciter field is flashed during this starting procedure.
(b) Run. Placing the MASTER SWITCH (S1) in the
PRIME-RUN position keeps the governor solenoid (K5)
energized thru the now closed oil pressure switch (S5) and fuel
will be supplied to the engine as long as the oil pressure is normal
and the high temperature switch (S4) is not activated by
high temperature.
(c) Stop. Placing the MASTER SWITCH (S1) in
the OFF position de-energizes the governor solenoid
(K5) shutting off fuel to stop the engine. High temperature
or low oil pressure will also shut the. engine
down.
(3) AC Circuitry. The main alternator (G1) is
wound with six pairs of coils that may be connected
by the AC Reconnect switch (S6) into various combinations,
the output of which is available at the load
terminal board (TB1). Circuit breaker (CB1) protects
the alternator from overloads. The volt/ampere select
switch (S8) permits switching voltmeter (MS) and
ammeter (M4) to read the load current and voltage
for the various arrangement of outputs.
Voltage regulator (A2) and current voltage transformer
CVT1 monitors the alternator output voltage