Hobart 90 C 20 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

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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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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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

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1-1 April 30/96 Revised

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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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1-1 April 30/96 Revised

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Hobart 90 C 20 Operation and Maintenance Manual

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