Section 1. Description; General - Hobart 6921 Series Operation And Maintenance Manual

OM-2040 / Operation and Maintenance Manual
90D20 / Generator Sets
TITLE = Chapter 1. Description / Operation

Section 1. Description

1. General

The Hobart generator sets covered by this manual are designed to provide power for maintenance and
startup of aircraft having 115/200-V AC, 3-phase, 400-Hz electrical systems. Five different series of
generator sets are covered by this manual. All generator sets in these series are driven by a Deutz
Diesel engine. Within the five different series of generator sets, 28 specifications of generator sets have
90-kVA, 400-Hz output power ratings. One specification, Specification Number 7126A has a 100-KVA,
400-Hz output power rating.
Generator sets are identified by a Specification Number which includes the Series Number and a dash
number suffix (i.e. -1, -2, etc.) . The suffix number indicates either the mounting design of the generator
set and/or one or more other major distinguishing features. Refer to the identification chart within this
section l to identify a particular unit.
Generator sets are commonly referred to as "ground power units", however, the equipment will be
identified in the manual as generator sets. Generator output power is principally used for operation of an
aircraft's electrical equipment when the on-board generators are not operating. For voltage and current
requirements, physical dimensions, weight and general output characteristics of a typical generator set
covered by this manual, refer to Figure 2.
Refer to Fig. 1 for identification of the main components . The equipment is a combination
motor-generator unit mounted on a welded steel frame. A superstructure supports the control box,
motor switch, load contactors, and other equipment. The output terminal is located to the rear at the
engine end, and the input panel is located to the front at the motor switch end. Right and left are
determined by standing at the rear and facing the machine. A sheet metal housing, or canopy, protects
electrical components. Removable panels and covers provide access for servicing and maintenance.
February 28/94
Revised
Chapter 1-1
Page 1