Hobart 6911-1, 6911A-1, 6911-2, 6911A-2, 6911-3 Operation And Maintenance Manual
...
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
6911-1, 6911A-1 Trailer or Truck
6911-2, 6911A-2 Trailer or Truck
6911-3, 6911A-3 Tractor
6911A-4
6911A-5*
MOUNTING
Fixed Unit With Fuel
Tank and Batteries
Trailer or Truck 489812A
VOLTAGE REGULATOR
USED
430391C
489812A
489812A
430391C
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 tobreak 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 below 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 voltage, 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 building 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 stemming 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 piping, 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 completely 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 conditioners.
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 treatment of all injury victims. Electric shock victims should be checked by a physician and taken to a hospital immediately 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 ELECTRICAL 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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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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SUBJECT CHAPTER/SECTION PAGE
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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Introduction August 5/89 Revised
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CHAPTER 1. DESCRIPTION/OPERATION
SECTION 1. DESCRIPTION
1. General
The generator sets
The various configurations of the set are identified by adding a dash number
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 models. 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 explained 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
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.
(or towed)
(see Fig. 1)
aircraft for operation of the aircraft’s electrical equipment when the on-board gener-
covered by the manual are identified by Series No. 6911 & 6911A.
(-1, -2, etc.)
suffix to the
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 assemblies in which they appear. Some of the main features are mentioned here and described briefly.
April 30/96 Revised 1-1
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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
1-1 April 30/96 Revised
Page 2
A. Protective Monitor
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A single, solid-state device
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
controls and equipment mounted in them. Each tray may be removed as an assembly by disconnecting 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),
(See OM-2020 in Chapter 6)
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
(4, Fig. 8)
provides automatic voltage regulation at the aircraft (or distribution
receives signals from all of the fault sensing units in the gen-
(Fig. 6)
which provide easy access to
adjustable voltage regulator
(See TM-759 in Chapter 6).
D. Test Circuitry
A receptacle connector
cuitry is provided for the attachment of a test box manufactured by Hobart Brothers. This test circuitry allows electricians to perform as many as twenty-four tests and checks from one location,
conveniently and easily.
(19, Fig. 9)
with wiring to various test points throughout the electrical cir-
E.E lectric Governor
The engine is equipped with an all electric type governor kit
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
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.
(Spec. 6911-2)
(5 and 12, Fig. 3)
the generator set is supplied with
and other special
(See Figure 21, Sec-
tion 4-3).
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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)
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)
Output power rating 90 kVA
Output Voltage 115/200-V
PHYSICAL
BASIC UNIT
TRAILER-MOUNTED UNIT
GENERATOR
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
1-1 April 30/96 Revised
Page 4
Specifications and Capabilities
Figure 2 (Sheet 1 of 2)
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Engine
Manufacturer Cummins
Model 6BTA5.9
Type Turbocharged, in-line, 6-cylinder, 4-cycle diesel
Displacement 359 cu. in. (5.8 liters)
Compression ratio 16.5:1
Firing order 1-5-3-6-2-4
Number of Main bearings 7
Horsepower at 2000 RPM 167
Governed speed 2000 RPM +/- 4.5%
Idle Speed 850 RPM +/- 25 RPM
Electrical System 12-volt
Oil capacity (with filter) 17.3 quarts (16.4 liters)
Oil capacity (without filter) 16.3 quarts (13.6 liters)
Coolant capacity 15.3 quarts (14.5 liters)
Fuel Diesel oil conforming to ASTM Spec.
D.975-66T, Nos. 1-D and 2-DD
Lube oil MIL-L-2104C or MIL-L-2104D
Specifications and Capabilities
Figure 2 (Sheet 2 of 2)
4. Identification
A. General
Generator sets are identifaied by their Specification numbers which consist of the Series number
plus a dash number (i.e. -1,-2, etc.) suffix. The suffix number indicates the mounting design of
the generator set. For example, Specification No. 6911 identifies a machine designed for mounting on a trailer or truck.
B. Generator Sets Available in 6911 and 6911A Series
The following identification chart lists machines currently available in each series.
SPECIFICATION
NUMBER
6911-1, 6911A-1 Trailer or Truck 430391C
MOUNTING VOLTAGE
REGULATOR
USED
6911-2, 6911A-2 Trailer or Truck 489812A
6911-3, 6911A-3 Tractor 489812A
6911A-4 Fixed, Fuel Tank and Batteries 430391C
6911A-5* Trailer or Truck 489812A
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5. Optional Equipment
Several items of optional equipment are available for the 6911 Series unit. Each piece of optional
equipment is covered by its own Instruction and Parts Manual and will not be covered in this basic
manual. When applicable, information for optional equipment will be located in Chapter 5.
Options are listed as follows:
A. Trailer
A four-wheel trailer with batteries and fuel tank is available.
B. Transformer-Rectifier
A transformer-rectifier
V, 400-Hz, AC power from the generator and converts it to a 28.5 V DC output.
C. Truck
Trucks with special bodies for mounting the generator set are available. Compartments in the
body are provided for batteries, cable-storage, etc. Trucks available are Ford, Chevrolet, and
GMC.
D. Second Output and Control Box
An auxiliary output and control box is available to provide a second independent 115-V AC output
circuit.
E. Quick Start Kit
(See Section 1-3, Para. 2C)
(T-R)
is available for use with the generator set. This T-R receives 115/200-
6. Canopy
A sheet metal enclosure, identified as a canopy
ator and electrical controls.
The canopy is designed to reduce the operational noise level in the immediate area of the machine.
Doors and panels are covered on the inside with Fiberglass acoustic material to reduce reflected and
conducted noise, and to absorb noise. Noise producing vibration in most frequently used doors on the
left side is reduced by the use of two-point slam locks. Less frequently used doors on the right side
are equipped with screw-operated latch fasteners which are tightened after latching to reduce vibration. Insulating strips around all doors also reduce noise. Metal strips are mounted horizontally across
the front grille to deflect engine fan exhaust air and noise upward.
(1, Fig. 1),
provides protection for the engine, gener-
Two large openings in the canopy top provide an entrance for cooling air and an access to internal
components. A hood-type cover is mounted about two inches above each opening. The cover is
flanged downward and extends beyond the edges of the upwardly flanged opening to prevent entrance of blowing rain while still allowing a good flow of air. Air enters the forward opening into the engine compartment and is discharged through the radiator by the engine fan. Air enters the rear
opening into the generator compartment. It is then circulated over generator controls and drawn into
the rear exciter and generator housings where it passes over all windings before being discharged by
the generator fan.
1-1 April 30/96 Revised
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This generator set is equipped with a canopy having doors on both sides. Panel mounted instruments
may be observed through two Plexiglass windows in the left rear door which covers the control box
and engine control panel. T he lower window is slanted outward at the bottom to provide access to engine controls when the door is closed. A centrally-located lifting eye attached to a lifting yoke extends
through the canopy top to provide an attaching point for chains, cables, or hook used to lift and move
the generator set.
7. Engine, Generator, and Controls Assembly
This assembly is the basic generator set without canopy. It 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. A superstructure, attached to the main frame, provides mounting facilities for the canopy, control box, and electrical equipment and controls.
A. Basic Engine
This generator set is equipped with a 6-cylinder, in-line, turbo-charged Cummins Diesel engine. See
Figure 2 for general specifications, and see Engine Operator’s Handbook in Chapter 6 for more detailed information.
B. Engine Manufacturer’s Equipment
As received from the engine manufacturer, the engine includes the following equipment which is
described in the Cummins Shop Manual
(1) Electronic stop control.
(2) Fuel filter.
(3) Reverse-flow, engine cooling fan to blow air outward through the radiator.
(Chapter 6)
.
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1. Mounting frame 8. Air cleaner 14. Engine control panel
2. Generator 9. Lifting yoke *15. Cable horn and clamp
3. Power module 10. Engine 16. Radiator
4. Control box 11. Engine exhaust pipe *17. Fuel valve solenoid
*5. Governor control box 12. Governor actuator 18. Oil pressure switch
*6. Starting fluid container 13. Output cable terminal 19. Muffler
7. Voltage regulator board
1-1 April 30/96 Revised
Page 8
* NOT ILLUSTRATED
Generator Set Components
Figure 3
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
quency)
response results in very close frequency control. Refer to the Barber Coleman Handbook in
Chapter 6 for a detailed description. A brief description is given below:
because it provides faster engine response to changes in load conditions. This fast
(and generator output fre-
The governor system consists of the following main components:
Magnetic pickup
Control unit
Actuator
(a) Magnetic pickup
The magnetic pickup 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.
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(b) Control unit
The control unit
nents. 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 12-V DC battery system.
(c) Actuator
The actuator
required to maintain a constant engine speed. The actuator is operated by a DC signal
from the control unit.
(2) Engine electrical system
Items in the 12-volt engine electrical system that are provided by Hobart Brothers are:
(a) A heavy-duty motor starter
(b) Alternator with voltage regulator
(c) Starting switch
(d) Wiring harness
(3) Engine protective devices
(a) High coolant temperature switch
(5,Fig.3)
(12, Fig. 3)
is a box containing a compact assembly of solid state compo-
supplies the force needed to move and position the fuel lever as
A high coolant temperature switch is mounted in the front of the cylinder block to monitor
the coolant temperature. If the coolant temperature reaches 210 degrees F
, this normally closed switch opens and actuates the fuel valve solenoid which shuts
C)
down the engine.
April 30/96 Revised 1-1
(99 degrees
Page 9
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(4) Air cleaner
(b) Oil pressure switch
A diaphragm-type switch monitors the pressure in the lubricating oil system. It is mounted
in the side of the cylinder block
(69 kPa)
10 psi
the engine.
, this switch opens and actuates the fuel valve solenoid which shuts down
(18, Fig. 3)
. If the pressure in the lube oil system falls to
The diesel-engine air cleaner
eliminator and a service indicator. The indicator functions to signal the operator when the cartridge needs changing. A red cylindrical “flag”
(1)
ing chamber
pressure. As the cartridge becomes loaded with dirt and air pressure within the cleaner lessens, the “flag” gradually rises higher in the glass viewing chamber. When the “flag” reaches
the top of the chamber, it locks in that position to warn the operator that the cartridge must be
changed. The “flag” is reset
of the indicator.
when air pressure within the air cleaner housing drops below the outside air
(Fig. 4)
(unlocked)
is a dry-cartridge type. It is equipped with a moisture
(2)
is forced upward in a glass enclosed view-
by pushing the reset button
(3)
located on the bottom
NOTE: Theserviceindicatorismountedontheenginecontrolpanelandconnectedtotheaircleaner
by a rubber hose. The indicator flag is visible only when the engine is running, or when the flag is
locked in WARNING position.
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April 30/96 Revised 1-1
1. Viewing chamber
2. Indicating “flag”
3. Reset button
Air Cleaner and Service Indicator
Figure 4
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(5) Exhaust system
The exhaust system consists of a special noise reducing muffler
(2)
nected by a pipe
rect exhaust and noise downward.
(6) Radiator
The radiator
assembly for cleaning and repair.
(16, Fig. 3)
to a conventional exhaust manifold
is a tube-type with bolted-on, top and bottom tanks which permit dis-
(3, Fig. 5)
(1).
Baffles in the tail pipe outlet di-
which is con-
1-1 April 30/96 Revised
Page 12
1. Exhaust Manifold
2. Exhaust Pipe
3. Muffler
Exhaust System
Figure 5
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D. Generator
The 400-Hz generator is a brushless, revolving field, three-phase, alternating current type. The rotor assembly is mounted by two, permanently lubricated, sealed, ball bearings. The front bearing
is supported by the fan housing; the rear bearing is mounted in the exciter housing. Both of these
housings are attached to the main generator stator housing. The front end of the rotor shaft extends forward beyond the rear bearing and into the exciter stator housing. The exciter rotor is
mounted on this shaft extension with a Woodruff key and is secured by a washer and 1/2"-13 thd,
cap screw. A rectifier with six diodes is mounted on the exciter rotor and converts exciter AC output to DC for excitation of the generator revolving fields. The exciter DC output to the generator
fields, and consequently the generator output, is controlled by the amount of DC voltage supplied
to exciter fields by the static voltage regulator. A centrifugal, radial-blade fan which is part of the
hub and coupling assembly, draws cooling air over all internal windings. Air enters at the exciter
end and is discharged at the drive end. The complete generator is bolted to the engine flywheel
housing.
E. Control Box Assembly
The control box
for generator and engine controls and monitoring equipment. The box is equipped with two,
drawer type trays which contain generator output control devices and monitoring instruments.
Trays slide in and out on nylon rollers for easy access to internally mounted components. Each
tray is easily removable by disconnecting an “Amphenol” connector, unlocking safety latches, and
sliding the complete tray assembly out of the control box.
A shielded, instrument panel light is mounted on the left side of the control box front panel, to illuminate controls and instruments in the trays.
(1) Generator control tray (See Figure 7)
The generator control tray contains instruments and controls for monitoring and controlling
the generator output.
(a) Resistors
Two, 10-ohm, 100-watt, ballast resistors
citer DC field circuit.
A variable resistor
rheostat
the voltage range through which the rheostat can control generator output voltage.
(Fig. 6)
(13)
is a sheet metal enclosure which houses and provides mounting facilities
(2)
are connected in series in the generator ex-
(1)
is connected in series between the manual control rectifier
. Its purpose is to adjust the DC voltage to the rheostat and thus determine
(14)
and
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(b) Generator output monitors (meters)
The generator output is monitored by three instruments; a frequency meter
(9)
, and an ammeter
ter
the frequency of the generator output alternating current in the range of 380 to 420 Hz
(cycles per second)
to-neutral
meter selector switch
scribed below.)
V. The ammeter is also 3-1/2-inch size and is graduated 0 t o 500 A. The amperage value
in each of the three phases may be read on the ammeter by selecting the desired phase
with switch
load current to a lesser value, of definite ratio, which will operate the ammeter movement
without damage. The ammeter dial scale is graduated and numbered so that the pointer
will indicate the true load current value rather than the meter movement current.
1-1 April 30/96 Revised
Page 14
(A-N, B-N and C-N)
The voltmeter has a 3-1/2-inch face and the scale is graduated 0 to 300
(6)
. Three ammeter current transformers
Control Box
Figure 6
(10)
, a voltme-
(7)
. The frequency meter is a resonant-reed type, and indicates
. The voltmeter indicates the generator output voltage in each phase-
or phase-to-phase
(6)
and the line selector switch
(A-B, B-C and C-A)
as selected by the
(5).(These switches will be de-
(Ref.4,Fig.11)
lower the output
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