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Hobart 90 C 20 Operation and Maintenance Manual

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OM-2031
080187
Revised 080589
Revised 032293
Revised 100195
Revised 043096
OPERATION AND MAINTENANCE
MANUAL
with
ILLUSTRATED PARTS LIST
for
ENGINE-DRIVEN GENERATOR SET
Series Numbers 6911 and 6911A
MODEL 90 C 20
90-KVA, 400-HZ, 115/200-V AC, 3-PHASE
SPECIFICATION
NUMBER
MOUNTING
VOLTAGE REGULATOR
USED
6911-1, 6911A-1 Trailer or Truck
430391C
6911-2, 6911A-2 Trailer or Truck
489812A
6911-3, 6911A-3 Tractor
489812A
6911A-4
Fixed Unit With Fuel
Tank and Batteries
430391C
6911A-5*
Trailer or Truck 489812A
Hobart Brothers Company
Ground Power Division
Troy, Ohio 45373
U.S.A.
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SAFETY INSTRUCTIONS AND WARNINGS FOR ELECTRICAL POWER EQUIPMENT
WARNING
ELECTRIC SHOCK can KILL. Do not touch live electrical parts.
ELECTRIC ARC FLASH can injure eyes, burn skin, cause equipment damage, and ignite combustible
material. DO NOT use power cables to break load and prevent tools from causing short circuits.
IMPROPER PHASE CONNECTION, PARALLELING, OR USE can damage this and attached
equipment.
Important:- Protect all operating personnel. Read, understand, and follow all instructions in
the Operating/Instruction Manual before installing, operating, or servicing the equipment. Keep
the manual available for future use by all operators.
A. GENERAL
Equipment that supplies electrical power can cause serious injury or death, or damage to other equipment
or property. The operator must strictly observe all safety rules and take precautionary actions. Safe practices
have been developed from past experience in the use of power source equipment. While certain practices be-
low apply only to electrically-powered equipment, other practices apply to engine-driven equipment, and some
practices to both.
B. SHOCK PREVENTION
Bare conductors, or terminals in the output circuit, or ungrounded, electrically-live equipment can fatally
shock a person. Have a certified electrician verify that the equipment is adequately grounded and learn what
terminals and parts are electrically HOT. Avoid hot spots on machine. Use proper safety clothing, procedures,
and test equipment.
The electrical resistance of the body is decreased when wet, permitting dangerous currents to flow
through it. When inspecting or servicing equipment, do not work in damp areas. Stand on a dry rubber mat
or dry wood, use insulating gloves when dampness or sweat cannot be avoided. Keep clothing dry, and
never work alone
1. Installation and Grounding of Electrically Powered Equipment
Equipment driven by electric motors (rather than by diesel or gasoline engines) must be installed and
maintained in accordance with the National Electrical Code, ANSI/NFPA 70, or other applicable codes. A
power disconnect switch or circuit breaker must be located at the equipment. Check the nameplate for volt-
age, frequency, and phase requirements. If only 3-phase power is available, connect any single-phase rated
equipment to only two wires of the 3-phase line. DO NOT CONNECT the equipment grounding conductor
(lead) to the third live wire of the 3-phase line, as this makes the equipment frame electrically HOT, which can
cause a fatal shock.
Always connect the grounding lead, if supplied in a power line cable, to the grounded switch box or build-
ing ground. If not provided, use a separate grounding lead. Ensure that the current (amperage) capacity of
the grounding lead will be adequate for the worst fault current situation. Refer to the National Electrical Code
ANSI/NFPA 70 for details. Do not remove plug ground prongs. Use correctly mating receptacles.
2. Output Cables and Terminals
Inspect cables frequently for damage to the insulation and the connectors. Replace or repair cracked or
worn cables immediately. Do not overload cables. Do not touch output terminal while equipment is energized.
3. Service and Maintenance
This equipment must be maintained in good electrical and mechanical condition to avoid hazards stem-
ming from disrepair. Report any equipment defect or safety hazard to the supervisor and discontinue use of
the equipment until its safety has been assured. Repairs should be made by qualified personnel only.
Before inspecting or servicing electrically-powered equipment, take the following precautions:
a. Shut OFF all power at the disconnecting switch or line breaker before inspecting or servicing the
equipment.
b. Lock switch OPEN (or remove line fuses) so that power cannot be turned on accidentally.
c. Disconnect power to equipment if it is out of service.
d. If troubleshooting must be done with the unit energized, have another person present who is trained in
turning off the equipment and providing or calling for first aid.
C . FIRE AND EXPLOSION PREVENTION
Fire and explosion are caused by electrical short circuits, combustible material near engine exhaust pip-
ing, misuse of batteries and fuel, or unsafe operating or fueling conditions.
1. Electrical Short Circuits and Overloads
Overloaded or shorted equipment can become hot enough to cause fires by self destruction or by causing
nearby combustibles to ignite. For electrically-powered equipment, provide primary input protection to remove
short circuited or heavily overloaded equipment from the line.
2. Batteries
Batteries may explode and/or give off flammable hydrogen gas. Acid and arcing from a ruptured battery
can cause fires and additional failures. When servicing,do not smoke, cause sparking, or use open flame
near the battery.
3. Engine Fuel
Use only approved fuel container or fueling system. Fires and explosions can occur if the fuel tank is not
grounded prior to or during fuel transfer. Shut unit DOWN before removing fuel tank cap. DO NOT com-
pletely fill tank, because heat from the equipment may cause fuel expansion overflow. Remove all spilled fuel
IMMEDIATELY, including any that penetrates the unit. After clean-up, open equipment doors and blow fumes
away with compressed air.
D. TOXIC FUME PREVENTION
Carbon monoxide - Engine exhaust fumes can kill and cause health problems. Pipe or vent the exhaust
fumes to a suitable exhaust duct or outdoors. Never locate engine exhausts near intake ducts of air condition-
ers.
E. BODILY INJURY PREVENTION
Serious injury can result from contact with fans inside some equipment. Shut DOWN such equipment for
inspection and routine maintenance. When equipment is in operation, use extreme care in doing necessary
trouble-shooting and adjustment. Do not remove guards while equipment is operating.
F. MEDICAL AND FIRST AID TREATMENT
First aid facilities and a qualified first aid person should be available for each shift for immediate treat-
ment of all injury victims. Electric shock victims should be checked by a physician and taken to a hospital im-
mediately if any abnormal signs are observed.
EMERGENCY FIRST AID
Call physician immediately. Seek additional assistance. Use First Aid techniques recommended
by American Red Cross until medical help arrives.
IF BREATHING IS DIFFICULT, give oxygen, if available, and have victim lie down. FOR ELECTRI-
CAL SHOCK, turn off power. Remove victim; if not breathing, begin artificial respiration, preferably
mouth-to-mouth. If no detectable pulse, begin external heart massage. CALL EMERGENCY RESCUE
SQUAD IMMEDIATELY.
G. EQUIPMENT PRECAUTIONARY LABELS
Inspect all precautionary labels on the equipment monthly. Order and inspect all labels that cannot be
easily read.
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Table of Contents
SUBJECT CHAPTER/SECTION PAGE
WARNING
LIST OF EFFECTIVE PAGES
INTRODUCTION
CHAPTER 1. DESCRIPTION/OPERATION
SECTION 1. DESCRIPTION 1-1 1
1. General 1-1 1
2. Orientation 1-1 1
3. Special Features 1-1 1
A.Protective Monitor 1-1 3
B.Pull-out Trays 1-1 3
C.Voltage Regulator 1-1 3
D.Test Circuitry 1-1 3
E.Electric Governor 1-1 3
F. “ROLL-OUT” FEATURE
(TOW TRACTOR-MOUNTED UNIT) 1-1 3
4. Identification 1-1 5
A. General 1-1 5
B. Generator Sets Available in 6911 Series. 1-1 5
5. Optional Equipment 1-1 6
A. Trailer 1-1 6
B. Transformer-Rectifier 1-1 6
C. Truck 1-1 6
D. Second Output and Control Box 1-1 6
E. Quick Start Kit 1-1 6
6. Canopy 1-1 6
7. Engine, Generator, and Controls
Assembly 1-1 7
A. Basic Engine 1-1 7
B. Engine Manufacturer’s Equipment 1-1 7
C. Hobart Engine Equipment 1-1 9
(1) Electric governor system 1-1 9
(a) Magnetic pickup 1-1 9
(b) Control unit 1-1 9
(c) Actuator 1-1 9
(2) Engine electrical system 1-1 9
(3) Engine protective devices 1-1 9
(4) Air cleaner 1-1 10
(5) Exhaust system 1-1 12
(6) Radiator 1-1 12
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SUBJECT CHAPTER/SECTION PAGE
D. Generator 1-1 13
E. Control Box Assembly 1-1 13
(1) Generator control tray 1-1 13
(a) Resistors 1-1 13
(b) Generator output monitors (meters) 1-1 14
(c) Meter and line switches 1-1 15
(d) Receptacle connector 1-1 15
(e) Tray 1-1 15
(f) Manual voltage control 1-1 15
(g) Excitation-deenergization relay 1-1 15
(2) Protective relay tray 1-1 15
(a) Sensing modules 1-1 17
(b) Memory and time delay module 1-1 17
(c) Indicating lights 1-1 18
(d) Plug-interlock relay 1-1 18
(e) Test-bank switch 1-1 18
(f) Resistor 1-1 18
(g) Fuse-interlock relay 1-1 18
(h) Connector 1-1 20
(k) Auxiliary underfrequency relay 1-1 20
F. Engine Control Panel 1-1 20
(1) Engine instruments 1-1 20
(2) Engine and generator controls 1-1 21
(3) Air cleaner indicator 1-1 22
(4) Test receptacle connector 1-1 22
G. Voltage Regulator 1-1 24
H. Power Module Panel Assembly 1-1 24
(1) Load contactor 1-1 24
(2) Current transformers 1-1 24
(3) Overload module 1-1 25
(4) Rectifier 1-1 25
(5) Terminal boards 1-1 25
8. Test Box 1-1 27
A. Description 1-1 27
B. Theory of Operation 1-1 28
SECTION 2. PREPARATION FOR USE,
STORAGE, OR SHIPPING 1-2 1
1. Preparation for Use 1-2 1
A. General 1-2 1
B. Inspection/Check 1-2 1
(a) Fuel 1-2 1
(b) Engine coolant 1-2 2
(c) Engine lubricating oil 1-2 2
C. Installing Output Cables 1-2 2
Units are generally shipped without generator
set-to-aircraft cables. 1-2 2
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Table of Contents August 5/89 Revised
Page 2
SUBJECT CHAPTER/SECTION PAGE
2. Preparation for Storage 1-2 4
A. General 1-2 4
B. Temporary Storage 1-2 5
C. Long Time Storage (Over 30 Days) 1-2 5
3. Preparation for Shipment
(Tractor-Mounted Units Only) 1-2 6
SECTION 3. OPERATION 1-3 1
1.General 1-3 1
2. Operating the Generator Set 1-3 1
A. Pre-start Inspection 1-3 1
B. Normal Engine Starting Procedures 1-3 1
C. Cold Weather Engine Starting Procedures 1-3 4
D. Preparation for Power Delivery 1-3 5
E. Power Delivery 1-3 6
F. Preparation for Power Delivery
(Manual Voltage Control) 1-3 6
G. Power Delivery (Manual Voltage Control) 1-3 7
H. Discontinue Power Delivery 1-3 7
K. Stopping the Engine 1-3 7
3. Test Box Operation 1-3 8
4. Transformer-Rectifier Operation 1-3 9
A. Direct Current Power Delivery 1-3 9
B. Simultaneous 28.5-V DC and 115-V AC
Power Delivery 1-3 10
6. Trailer Operation 1-3 11
A. Towing 1-3 11
B. Parking 1-3 11
CHAPTER 2. SERVICE
SECTION 1. MAINTENANCE 2-1 1
1. General 2-1 1
2. Operation of Roll-Out Feature
(For Tractor-Mounted Units Only) 2-1 1
A. Roll Generator-Set Out for Service 2-1 1
B. Roll Generator-Set In to Normal Position 2-1 1
3. Inspection 2-1 1
4. Lubrication 2-1 3
A. General 2-1 3
B. Generator 2-1 3
C. Generator Controls 2-1 3
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SUBJECT CHAPTER/SECTION PAGE
D. Engine 2-1 3
(1) Lubrication schedule 2-1 3
(2) Oil specification 2-1 3
(3) Oil viscosity 2-1 3
(4) Changing engine oil 2-1 4
(5) Changing engine oil filter 2-1 4
E. Starter 2-1 4
5. Air Cleaner Service 2-1 5
A. Cartridge Removal 2-1 5
B. Cartridge Installation 2-1 5
6. Engine Fuel 2-1 6
A. Quality 2-1 6
B. Fuel Filter 2-1 6
7. Engine Cooling System 2-1 6
A. General 2-1 6
B. Radiator Cap 2-1 6
(1) General 2-1 6
(2) Removal 2-1 6
(3) Installation 2-1 7
C. Warm Weather Operation 2-1 7
D. Cold Weather Operation 2-1 7
(1) General 2-1 7
(2) Checking coolant solution 2-1 7
(3) Preparing the coolant solution 2-1 7
(4) Installing the antifreeze solution 2-1 7
E. Draining the Cooling System 2-1 8
F. Cleaning the Cooling System 2-1 8
G. Cleaning the Radiator Core 2-1 9
H. Filling the Cooling System 2-1 9
8. Generator Maintenance 2-1 9
A. Cleaning 2-1 9
B. Adjustment 2-1 10
9. Drive Belts 2-1 10
A. Checking Belt Tension 2-1 10
B. Belt Adjustment 2-1 10
10. Trailer, Truck and Battery Maintenance 2-1 10
11. Service Helps 2-1 10
A. Wiring 2-1 10
B.Control Box Trays 2-1 10
C. Generator Exciter 2-1 11
D. Engine Control Panel 2-1 12
SECTION 2. INSPECTION/CHECK 2-2 1
1. General 2-2 1
2. Engine 2-2 1
A. Fuel (See Fig. 1 for time schedules) 2-2 1
B. Lubrication 2-2 1
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SUBJECT CHAPTER/SECTION PAGE
C. Coolant 2-2 1
D. V-Belts 2-2 1
E. Exhaust System 2-2 1
3.Electrical System (12-V DC) 2-2 3
A. Lights 2-2 3
B. Fuses 2-2 3
C. Wiring and Connections 2-2 3
4. Electrical System (115-V AC) 2-2 4
A. Monitoring Instruments 2-2 4
B. Indicating Lights 2-2 4
C. Protective Modules 2-2 4
D. Wiring and Connections 2-2 4
5. Trailer and Truck 2-2 5
SECTION 3. ADJUSTMENT/TEST 2-3 1
1. General 2-3 1
2. Generator Set Test 2-3 1
A. Pre-operational Test Procedures 2-3 1
B. Operational Test Procedures 2-3 5
3. Generator Set Adjustment 2-3 10
A. Generator Adjustment 2-3 10
B. Generator Control Adjustments 2-3 10
C. Basic Engine Adjustments 2-3 10
D. Engine Accessories Adjustment 2-3 10
E. Electric Governor System Adjustment 2-3 11
(1) Actuator linkage adjustment 2-3 11
(2) Magnetic pickup adjustment 2-3 12
(3) Adjustment and Test of Controller and Actuator 2-3 14
(4) Checking Magnetic Pick-up signal 2-3 16
5. Generator and Exciter Test 2-3 16
6. Diode Test 2-3 17
A. Disconnect diode lead(s). 2-3 17
CHAPTER 3. TROUBLESHOOTING
SECTION 1. TROUBLE SHOOTING
PROCEDURES 3-1 1
1. General 3-1 1
2. Trouble Shooting Chart 3-1 1
3. Equipment for Troubleshooting 3-1 2
4. Safety 3-1 2
5. Parts Replacement 3-1 2
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6. Test Values 3-1 3
7. Checking Connections and Leads 3-1 3
8. Electric Governor Trouble Shooting 3-1 3
9. Engine Trouble Shooting Procedures 3-1 4
A. General 3-1 4
CHAPTER 4. ILLUSTRATED PARTS LIST
SECTION 1. INTRODUCTION 4-1 1
1. General 4-1 1
2. Purpose 4-1 1
3. Arrangement 4-1 1
4. Explanation of Parts List 4-1 1
A. Contents 4-1 1
B. Parts List Form 4-1 1
SECTION 2. MANUFACTURER’S CODES 4-2 1
1. Explanation of Manufacturer’s (Vendor)
Code List 4-2 1
SECTION 3. PARTS LIST 4-3 1
1. Explanation of Parts List Arrangement 4-3 1
2. Symbols and Abbreviations 4-3 1
SECTION 4. NUMERICAL INDEX 4-4 1
1. Explanation of Numerical Index 4-4 1
CHAPTER 5. OPTIONAL EQUIPMENT
CHAPTER 6. MANUFACTURER’S LITERATURE
UNUSUAL SERVICE CONDITIONS
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INTRODUCTION
This manual contains operation and maintenance information for a series of 400-Hertz generator sets
manufactured by Hobart Brothers Company, Power Systems Group, Troy, Ohio 45373.
This manual is not intended to be a textbook on electricity or electronics. Its primary purpose is to provide
information and instructions to experienced operators, electricians, and mechanics who have never seen or
operated this equipment. It is the intent of this manual to guide and assist operators and maintenance people
in the proper use and care of the equipment.
Use of the manual should not be put off until a trouble or need for help develops. Read the instructions before
starting the unit. Learn to use the manual and to locate information contained in it. Its style and arrangement
are very similar to commercial aircraft manuals. The manual is divided into six chapters. Each chapter is
divided into as many sections as required. Each new section starts with page 1. Each page is identified by
chapter, section and page number, which are located in the lower, outside corner. When information located
in another portion of the manual is referred to, its location is identified by a chapter, section, and paragraph, or
figure number. For example, “
(See 2-3, Para. B)”
refers to information located in Chapter 2, Section 3,
Paragraph B. If a Chapter and Section are not indicated in a reference, the referenced material is located in
the same section as the reference, Example,
(See Para. B).
In addition to operation and maintenance instructions, the manual contains an illustrated parts list in Chapter
4, and a collection of manufacturer’s literature and supplemental information in Chapter 6.
Content of the manual is arranged as follows:
Chapter 1. Description/Operation
Chapter 2. Servicing
Chapter 3. Troubleshooting
Chapter 4. Illustrated Parts List
Chapter 5. Optional Equipment
Chapter 6. Manufacturer’s Literature
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CHAPTER 1. DESCRIPTION/OPERATION
SECTION 1. DESCRIPTION
1. General
The generator sets
(see Fig. 1)
covered by the manual are identified by Series No. 6911 & 6911A.
The various configurations of the set are identified by adding a dash number
(-1, -2, etc.)
suffix to the
Series number.
The generator sets in the 6911 series feature armatures with Hoover Bearings, Browning Coupler,
and different magnetic pole construction for the generator revolving field. This new armature can be
easily identified by the two copper rings on each end of the field coils and copper wedges between
the magnetic poles.
Series 6911A generator sets feature the same magnetic pole construction for the generator revolving
field as Series 6911 generator sets. In addition, Series 6911A generator sets also feature wide-type
Fafnir bearings on the generator.
The basic generator set which includes the engine, generator and all controls is identical for all mod-
els. Differences between models are those required by their respective mounting, such as trailer
mounting, tow tractor mounting, etc. Identification of different models within the Series will be ex-
plained later in the Description.
Information and instructions throughout the manual apply to all models. Information which applies only
to a certain model will be qualified and identified as such.
The purpose of the generator set is to generate and deliver regulated, 400-Hz electrical power to a
parked
(or towed)
aircraft for operation of the aircraft’s electrical equipment when the on-board gener-
ators are not running. The engine, generator, and controls are designed into a compact unit which is
easily removable from a tow tractor. See Figure 2 for specifications and capabilities.
2. Orientation
For purpose of orientation and to familiarize operators and maintenance personnel with the location of
components, the radiator is considered to be at the FRONT of the unit. The generator and controls
are at the REAR.
RIGHT and LEFT are determined by standing at the rear end facing the machine. Thus, the generator
control box, output receptacle connector, and engine control panel are mounted on the LEFT side at
the REAR of the unit.
3. Special Features
The generator set has many special features which are later described more fully under the assem-
blies in which they appear. Some of the main features are mentioned here and described briefly.
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1. Canopy 6. Output cable horn
2. Access-vent covers 7. Mounting frame
3. Lifting eye 8. Engine fan exhaust deflectors
4. Windows 9. Engine exhaust pipe
5. Output receptacle cover 10. Radiator cap access cover
Generator Set
Figure 1
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A. Protective Monitor
A single, solid-state device
(4, Fig. 8)
receives signals from all of the fault sensing units in the gen-
erator output circuit and functions to cause the load to be disconnected from the generator if an
abnormal condition of voltage, frequency, or load develops.
B. Pull-out Trays
The control box is equipped with pull-out, drawer-type trays
(Fig. 6)
which provide easy access to
controls and equipment mounted in them. Each tray may be removed as an assembly by discon-
necting a single quick-disconnect connector and tripping two safety latches.
C. Voltage Regulator
A solid-state
(used on 6911-2, 6911-3, 6911A-2, 6911A-3 units),
adjustable voltage regulator
(See OM-2020 in Chapter 6)
provides automatic voltage regulation at the aircraft (or distribution
panel when applicable). The regulator is also adjustable for a variety of output cable sizes and
lengths.A magamp type voltage regulator is used on Specs. 6911-1, 6911A-1, 6911A-4 units
(See TM-759 in Chapter 6).
D. Test Circuitry
A receptacle connector
(19, Fig. 9)
with wiring to various test points throughout the electrical cir-
cuitry is provided for the attachment of a test box manufactured by Hobart Brothers. This test cir-
cuitry allows electricians to perform as many as twenty-four tests and checks from one location,
conveniently and easily.
E.E lectric Governor
The engine is equipped with an all electric type governor kit
(5 and 12, Fig. 3)
and other special
equipment more fully described under the engine description.
F. “ROLL-OUT” FEATURE (TOW TRACTOR-MOUNTED UNIT)
For a generator set mounted on a tow tractor
(Spec. 6911-2)
the generator set is supplied with
two-channel-like tracks which are floor mounted in the generator compartment of the tow tractor.
Tracks are equipped with cam-follower, needle-bearing rollers which support the generator set
and allow it to roll in-and-out easily for servicing and maintenance. Additional rollers are mounted
on each side of the generator set main frame, near the rear, to add stability and to prevent the
unit from tipping downward at the front when it is rolled outward for service.
(See Figure 21, Sec-
tion 4-3).
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PHYSICAL
BASIC UNIT
Length overall 82 inches (2082.8 mm)
Width 36 inches (914.4 mm)
Height overall 43 inches (1092.2 mm)
Weight 3050 pounds (1383.2 kg)
TRAILER-MOUNTED UNIT
Length overall 100 inches (2540 mm)
Width 78 inches (1981.2 mm)
Height overall 72 inches (1828.8 mm)
Weight 4950 pounds (2244.9 kg)
GENERATOR
Output power rating 90 kVA
Output Voltage 115/200-V
Rated load capacity 260-A
Frequency (cycles per second) 400-Hz
Output kilowatts 72-kW
Power factor 0.8 PF
Duty cycle 100%
Operating speed at 400-Hz 2000 RPM
Overload Capacity
(125 % of rated lad capacity
325 A
GENERATOR PROTECTIVE SYSTEM
Overvoltage relay trips 130-V to 134-V; resets 125-V
Undervoltage relay trips 102-V or below; resets 110-V
Overfrequency relay trips 415-Hz to 425-Hz; resets 410-Hz
Underfrequency relay trips 375-Hz to 385-Hz; resets 385-Hz
Overload relay trips at 112-kVA in less than 5 minutes
Undervoltage time delay relay trips 4 to 12 seconds
Specifications and Capabilities
Figure 2 (Sheet 1 of 2)
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