Engine, Generator And Controls Assembly; Basic Engine; Engine Manufacturer's Equipment; Hobart Engine Equipment - Hobart 6921 Series Operation And Maintenance Manual

OM-2040 / Operation and Maintenance Manual
90D20 / Generator Sets

5. Engine, Generator and Controls Assembly

The generator set includes all components required to generate and regulate 400 Hz, 115/200 V,
three-phase power, and is operable when provided with fuel and 12-V DC power. The engine-
generator assembly is mounted on a welded steel frame which provides mounting facilities for the
canopy, control box and electrical equipment and controls.
a. Basic Engine
The 90 kVA generator sets covered by this manual are equipped with a six cylinder, in-line diesel
engine, and is manufactured by KHO Deutz, 5000 Koln, Deutz-MulheimerStrabe 111.
b. Engine Manufacturer's Equipment
As received from the engine manufacturer, the engine includes the following equipment which is
described in the Deutz Diesel Operators Manual. Refer to Figure 4.
(1) Twelve volt electrical system includes starter and alternator with built-in voltage regulator.
(2) Fuel strainer and fuel filter.
(3) Full-flow oil filter.
(4) (4) Automatic shutdown system including high oil temperature and low oil pressure sensing
switches.
(5) (5) Speed limiting governor.
c. Hobart Engine Equipment
The engine is modified at Hobart Brothers by the addition of the following equipment:
(1) Electric governor system
An electric governor kit is installed on the engine to replace a conventional, mechanical type.
The electric governor was selected for control of engine speed (and generator output frequency)
because it provides faster engine response to changes in load conditions. The governor system
consists of (a) the Magnetic pickup (b) the Control unit, and (c) the Actuator. A brief
description is given below:
a. Magnetic pickup
The magnetic pickup (17, Fig. 4) is a device for detecting the speed of the engine. It is
mounted in the flywheel housing directly over the ring gear. It produces an AC signal to the
control unit when the ferrous flywheel teeth pass through the magnetic field at the end of the
pickup.
b. Control unit
The control unit (4, Fig. 3) is a box containing a compact assembly of solid state
components. It receives an AC signal from the magnetic pickup and senses speed changes
in the engine. It provides a voltage signal to the actuator which causes the actuator to move
the fuel control lever as required to maintain a predetermined engine speed. Its power is
received from the two 12-V DC battery system.
c. Actuator
The actuator (1, Fig. 5) supplies the force needed to move and position the fuel lever as
required to maintain a constant engine speed. The actuator is operated by a DC signal from
the control unit.
February 28/94
Revised
Chapter 1-1
Page 7