OPERATION AND MAINTENANCE MANUAL. ILLUSTRATED PARTS for

Transcription

1 Revised OPERATION AND MAINTENANCE MANUAL with ILLUSTRATED PARTS for LIST ENGINE DRIVEN GENERATOR SETS 60-kVA, 400-Hz, 115/200-V AC, 3-Phase Units with PERKINS DIESEL ENGINE Type SPECIFICATION MOUNTING VOLTAGE REGULATOR , 6824A-1 Trailer or Truck C , 6824A-2 Tractor C , 6824A-3 Stationary: With Fuel Tank & Batteries C , 6824A-4 Trailer or Truck, Dual Output C 6824A-5 Trailer or Truck A-6 Tractor A-7 Stationary: With Fuel Tank & Batteries A-8 Trailer or Truck, Dual Output HOBART BROTHERS COMPANY Airport Systems Group Troy, Ohio U.S.A.

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3 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 attache 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. 1. 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 a. 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. b. 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. May 31/94 Revised Safety Warnings Page 1

4 c. 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. (1) Before inspecting or servicing electrically-powered equipment, take the following precautions: (2) Shut OFF all power at the disconnecting switch or line breaker before inspecting or servicing the equipment. (3) Lock switch OPEN (or remove line fuses) so that power cannot be turned on accidentally. (4) Disconnect power to equipment if it is out of service. (5) 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. 2. 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. a. 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. b. 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. c. 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. 3. 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. 4. 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. 5. 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. Safety Warnings Page 2 May 31/94 Revised

5 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. 6. Equipment Precautionary Labels Inspect all precautionary labels on the equipment monthly. Order and inspect all labels that cannot be easily read. May 31/94 Revised Safety Warnings Page 3

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7 Introduction This manual contains operation and maintenance information for a series of 400-Hertz generator sets manufactured by Hobart Brothers Company, Power Systems Division, Troy, Ohio 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 May 31/94 Revised Introduction Page 1

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9 Table of Contents SUBJECT CHAPTER/SECTION PAGE Chapter 1. Description / Operation Section 1. Description General Orientation Special Features a. Roll-Out Feature (Tow Tractor -Mounted Unit) i b. Protective Monitor c. Pull-out Trays d. Voltage Regulator e. Test Circuitry f. Electric Governor Identification Canopy Optional Equipment a. Trailer b. Transformer-Rectifier c. Truck d. Second Output and Control Box e. Quick Start Kit Engine, Generator, and Controls Assembly a. Basic Engine b. Engine Manufacturer s Equipment c. Hobart Engine Equipment d. Generator e. Control Box Assembly f. Engine Control Panel g. Voltage Regulator h. Power Module Panel Assembly Test Box a. Description b. Theory of Operation Dual Output Units (Specifications , 6824A-4 and 6824A-8) May 31/94 Revised Table of Contents Page 1

10 SUBJECT CHAPTER/SECTION PAGE Section 2. Preparation For Use, Storage, Or Shipping Preparation for Use a. General b. Inspection/Check c. Installing Output Cables Preparation for Storage General Temporary Storage Long Time Storage (Over 30 Days) Preparation for Shipment (Tractor- Mounted Units Only) Section 3. Operation General Operating the Generator Set a. Pre-start Inspection b. Normal Engine Starting Procedures c. Cold Weather Engine Starting Procedures d. Preparation for Power Delivery (Normal Automatic Voltage Control) e. Power Delivery (Automatic Voltage Control) f. Preparation for Power Delivery (Manual Voltage Control) g. Power Delivery (Manual Voltage Control) h. Discontinue Power Delivery i. Stopping the Engine Test Box Operation Transformer-Rectifier Operation a. Direct Current Power Delivery b. Simultaneous 28.5-V DC and 115-V AC Power Delivery No. 2 Output Operation (Specifications , 6824A-4 and 6824A-8) a. Power Delivery b. Discontinue Power Delivery Trailer Operation a. Towing b. Parking Table of Contents Page 2 May 31/94 Revised

11 SUBJECT CHAPTER/SECTION PAGE Chapter 2. Service Section 1. Maintenance General Operation of Roll-Out Feature (For Tractor-Mounted Units Only) a. Roll Generator-Set Out for Service b. Roll Generator-Set In to Normal Position Inspection Lubrication a. General b. Generator c. Generator Controls d. Engine e. Starter Air Cleaner Service a. Cartridge Removal b. Cartridge Installation Engine Fuel Quality Fuel Filter Engine Cooling System a. General b. Radiator Cap c. Warm Weather Operation d. Cold Weather Operation e. Draining the Cooling System f. Cleaning the Cooling System g. Cleaning the Radiator Core h. Filling the Cooling System Generator Maintenance a. Cleaning b. Adjustment Drive Belts a. Checking Belt Tension b. Belt Adjustment Trailer, Truck and Battery Maintenance Service Helps a. Wiring b. Control Box Trays c. Generator Exciter d. Engine Control Panel May 31/94 Revised Table of Contents Page 3

12 SUBJECT CHAPTER/SECTION PAGE Section 2. Inspection / Check General Engine a. Fuel (See Fig. 1 for time schedules) b. Lubrication c. C. Coolant d. V-Belts e. Exhaust System Electrical System (12-V DC) a. Lights b. Fuses c. Wiring and Connections Electrical System (115-V AC) a. Monitoring Instruments b. Indicating Lights c. Protective Modules d. Wiring and Connections Trailer and Truck Section 3. Adjustment / Test General Test Panels a. Generator Set Removed from Tractor b. Generator Set in Tow Tractor Generator Set Test a. Pre-operational Test Procedures b. Operational Test Procedures Generator Set Adjustment a. Generator Adjustment b. Generator Control Adjustments c. Basic Engine Adjustments d. Engine Accessories Adjustment e. Electric Governor System Adjustment Generator and Exciter Test Diode Test Additional Test for Dual Output Unit Table of Contents Page 4 May 31/94 Revised

13 SUBJECT CHAPTER/SECTION PAGE Chapter 3. Troubleshooting Procedures 1 1 Section 1. Troubleshooting General a. Troubleshooting b. Description c. Use of the Troubleshooting Chart Equipment for Troubleshooting Safety Parts Replacement Test Values Check Connections and Leads Electric Governor Trouble Shooting Engine Trouble Shooting Procedures a. General Illustrations Chapter 4. Illustrated Parts List Section 1. Introduction General Purpose Arrangement Explanation of Parts List a. Contents b. Parts List Form Section 2. Manufacturer s Codes Explanation of Manufacturer s 4-2 (Vendor) Code List Section 3. Parts List Explanation of Parts List Arrangement Symbols and Abbreviations Section 4. Numerical Index Explanation of Numerical Index Chapter 5. Optional Equipment Chapter 6. Manufacturer s Literature Unusual Service Conditions May 31/94 Revised Table of Contents Page 5

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15 Chapter 1. Description / Operation Section 1. Description 1. General The basic generator sets (see Fig. 1) covered by the manual are identified by Series No. 6824and Series No. 6824A. 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 6824A 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. 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 (or towed) aircraft for operation of the aircraft s electrical equipment when the on-board generators 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 assemblies in which they appear. Some of the main features are mentioned here and described briefly as follows. a. Roll-Out Feature (Tow Tractor-Mounted Unit) For a generator set mounted on a tow tractor 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, Section 4-3.) May 31/94 Revised 1-1 Page 1

16 The set is secured in mounted position by two retaining brackets attached at the front of the unit (See 2-1, Fig. 2). The removal of two screws from the brackets allows the set to be rolled out approximately 38 inches, where a stop-bar on the main frame contacts a stop-block in the left track to prevent further outward travel. b. Protective Monitor A single, solid-state device (4, Fig. 8) receives signals from all of the fault sensing units in the generator output circuit and functions to cause the load to be disconnected from the generator if an abnormal condition of voltage, frequency, or load develops. c. 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 disconnecting a single quick-disconnect connector and tripping two safety latches. d. Voltage Regulator A solid-state, adjustable voltage regulator (Fig. 10) 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. e. Test Circuitry A receptacle connector (19, Fig. 9) with wiring to various test points throughout the electrical circuitry 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. f. Electric 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. 4. Identification Generator sets are identified by their Specification number, which consists of a 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 number 6824A-2 identifies a machine designed for mounting on a tow tractor. The following identification chart identifies in greater detail the machines covered by this manual. SPECIFICATION No , 6824A-1, and 6824A , 6824A-2, and 6824A , 6824A-3, and 6824A , 6824A-4, and 6824A-8 CHARACTERISTICS Designed for trailer or truck mounting. 12-V DC electrical power and fuel to be supplied from facilities on trailer or truck. Designed for mounting on a tow tractor. 12-V DC electrical power and fuel to be supplied by tow tractor. Furnished with roll-out tracks for mounting on tow tractor. Designed for stationary mounting. Equipped with two 12-V batteries and fuel tank. Dual output unit for trailer or truck mounting. 12-V DC electrical power and fuel to be supplied from facilities on trailer or truck. Generator Set Identification Chart 1-1 May 31/94 Revised Page 2

17 1. Canopy 6. Mounting frame 2. Lifting eye 7. Engine fan exhaust deflectors 3. Windows 8. Engine exhaust pipe 4. Output receptacle cover 9. Radiator cap access cover 5. Output cable horn Generator Set Figure 1 May 31/94 Revised 1-1 Page 3

18 PHYSICAL Length (stationary units) Width Height (overall) Weight (approximately) 82 inches ( mm) 36 inches (914.4mm) 43 inches (1092.2mm) 3300 pounds ( kg) GENERATOR CAPABILITIES Output power rating 60 KVA Output voltage 115/200 VAC Rated load capacity 173 A Frequency/cycles per second 400 Hz Output Kilowatts 48 KW Power factor 0.8 PF Duty cycle 100% Operating speed 2000 RPM Overload capacity (125% of rated load) 216 A Output cable size 2/0 GENERATOR PROTECTIVE SYSTEM Overvoltage relay Undervoltage relay Overfrequency relay Underfrequency relay Undervoltage time delay Overload relay Trips 130 V to 134 V; resets 125 V Trips 93 V to 102 V; resets 110 V Trips 415 Hz to 425 Hz; resets 410 Hz Trips 375 Hz to 385 Hz; resets 385 Hz 4 to 12 seconds, depending upon adjustment Trips at 125% rated load in less than 5 minutes ENGINE Manufacturer Perkins Engines, Inc. Model T Type In-line, 6-cylinder, 4-cycle diesel Displacement 354 cu. in. (5.8 liters) Compression ratio 16:1 Firing order Number of main bearings 7 Horsepower at 2000 RPM 107 Governed speed 2000 RPM + / - 4.5% Idle speed / - 25 RPM Electrical system 12 volt Oil Capacity (W/Filter) 15 Quarts (14 liters) Oil Capacity (W/O Filter) 14 Quarts (13.6 liters) Coolant capacity (approx.) 20 quarts (19 liters) Fuel Diesel oil conformint to ASTM Specification D T, No. 1-D and 2-D MIL-L-2104B Specifications and Capabilities Figure May 31/94 Revised Page 4

19 5. Canopy A sheet metal enclosure, identified as a canopy (1, Fig. 1), provides protection for the engine, generator 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. 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. All generator sets in this Series except the tractor-mounted unit are equipped with a canopy having doors on both sides. Tractor-mounted units have two large removable panels on the right side mainly because the right side of the machine is not accessible when mounted on a tow tractor, and secondly because the thick doors would not allow mounting in the limited space available on the tractor. Panel mounted instruments may be observed through two Plexiglass windows in the left rear door which covers the control box and engine control panel. The 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. 6. Optional Equipment Several items of optional equipment are available for units covered in this manual. 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 (T-R) is available for use with the generator set. This T-R receives 115/200-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 generator set mounting 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. This option is for -1, -2 and -3 generator set specification numbers if a second output is desired for a machine purchased before dual output machines (-4 specification numbers) were available, or if a second output is desired for a tractor-mount or stationary unit. e. Quick Start Kit (See Section 1-3, Para. 2C) May 31/94 Revised 1-1 Page 5

20 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, threephase 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 Perkins 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 Perkins Shop Manual (Chapter 6). (1) Electronic stop control. (2) Fuel filter. (3) Reverse-flow, engine cooling fan to blow air outward through the radiator. 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. This fast response results in very close frequency control. Refer to the Barber-Colman instruction book in Chapter 6 for a detailed description. A brief description is given below: 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. b. Control unit The control unit (5, 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 12-V DC battery system. c. Actuator The actuator (12, Fig. 3) 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. (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 1-1 May 31/94 Revised Page 6

21 1. Mounting frame 7. Voltage regulator 13. Output cable terminal board 2. Generator 8. Air cleaner 14. Engine control panel 3. Power module 9. Lifting yoke 15. Cable horn and clamp 4. Control box 10. Engine 16. Radiator 5. Governor control box 11. Engine exhaust pipe 17. Oil pressure switch 6. Starting fluid container * 12. Governor actuator * Optional Generator Set Components Figure 3 May 31/94 Revised 1-1 Page 7

22 (3) Engine protective devices a. High coolant temperature switch 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 (99 degrees C), this normally closed switch opens and actuates the fuel valve solenoid which shuts down the engine. 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 (18, Fig. 3). If the pressure in the lube oil system falls to 10 psi (69 kpa), this switch opens and actuates the fuel valve solenoid which shuts down the engine. (4) Air cleaner The diesel-engine air cleaner (Fig. 4) is a dry-cartridge type. It is equipped with a moisture eliminator and a service indicator. The indicator functions to signal the operator when the cartridge needs changing. A red cylindrical flag (2) is forced upward in a glass enclosed viewing chamber (1) when air pressure within the air cleaner housing drops below the outside air 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 (unlocked) by pushing the reset button (3) located on the bottom of the indicator. NOTE: The service indicator is mounted on the engine control panel and connected to the air cleaner by a rubber hose. The indicator flag is visible only when the engine is running, or when the flag is locked in WARNING position. Air Cleaner and Service Indicator Figure May 31/94 Revised Page 8

23 (5) Exhaust system The exhaust system consists of a special noise reducing muffler (3, Fig. 5) which is connected by a pipe (2) to a conventional exhaust manifold (1). Baffles in the tail pipe outlet direct exhaust and noise downward. Noise Reduction Exhaust System Figure 5 (6) Radiator The radiator (16, Fig. 3) is a tube type with bolted-on, top and bottom tanks which permit disassembly for cleaning and repair. 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 (Fig. 6) is a sheet metal enclosure which houses and provides mounting facilities 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. May 31/94 Revised 1-1 Page 9

24 Control Box Figure 6 (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 (2) are connected in series in the generator exciter DC field circuit. A variable resistor (1) is connected in series between the manual control rectifier (14) and rheostat (13). Its purpose is to adjust the DC voltage to the rheostat and thus determine the voltage range through which the rheostat can control generator output voltage. b. Generator output monitors (meters) The generator output is monitored by three instruments; a frequency meter (10), a voltmeter (9), and an ammeter (7). The frequency meter is a resonant-reed type, and indicates the frequency of the generator output alternating current in the range of 380 to 420 Hz (cycles per second). The voltmeter indicates the generator output voltage in each phase-to-neutral (A-N, B-N and C-N) or phase-to-phase (A-B, B-C and C-A) as selected by the meter selector switch (6) and the line selector switch (5). (These switches will be described below.) The voltmeter has a 3-1/2-inch face and the scale is graduated 0 to 300 V. The ammeter is also 3-1/2-inch size and is graduated 0 to 500 A. The amperage value in each of the three phases may be read on the ammeter by selecting the desired phase with switch (6). Three ammeter current transformers (Ref. 4, Fig. 11) lower the output 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 May 31/94 Revised Page 10

25 c. Meter and line switches These switches provide a means of selecting and determining which phase of voltage and current is indicated on the voltmeter and ammeter and whether the voltage is line-to-neutral or line-to-line. The meter switch (6) is a four-position, rotary type. A nameplate (4), located under the switch knob, is marked and lettered to indicate the three functional positions of the meter switch. (When the knob is pointing straight down, the switch is OFF.) The line switch (5) is a twoposition, toggle switch used to select either line-to-neutral or lineto-line voltage to the voltmeter. The nameplate is also marked to indicate the position of this switch. d. Receptacle connector An Amphenol connector (12) provides a means of quickly disconnecting all wires to control box components. e. Tray The tray (15) slides in and out on nylon rollers. It is secured in place by a twist-lock, screw fastener (8). f. Manual voltage control When the automatic manual switch (11) is placed in MANUAL position, AC power is supplied to the rectifier (14) rather than to the automatic voltage regulator. The DC output of the rectifier is routed to the exciter field through a rheostat (13). The generator output voltage is thereby manually controlled by adjustment of the rheostat. g. Excitation-deenergization relay The purpose of this relay (3) is to allow automatic excitation to be connected to the exciter field only when engine speed is being controlled by the electric governor. (2) Protective relay tray (see Figure 8) The bottom tray in the control box is identified as the protective relay tray and contains electrical and safety devices designed to protect the aircraft electrical system against damage which could result from overvoltage, undervoltage, overfrequency, or underfrequency. The tray also contains devices for protection and control of the generator output electrical system. a. Sensing modules The voltage sensing module (5) and frequency sensing module (6) are connected to generator output leads between the generator and load contactor. These solid-state modules sense any abnormal condition of voltage or frequency and signal the solid-state circuitry of the memory and time delay module (4) to open the load contactor and disconnect output to the aircraft. Trip values are adjustable, however, adjustments should be made ONLY under laboratory conditions. A solid-state overload signaling device (Ref. 7, Fig 11) is also connected to the protective monitor module and performs a function similar to the voltage and frequency sensing modules. Trip values for protective circuits are as follows: Overvoltage trips at 130 V to 134 V Undervoltage trips at 102 V or below Overfrequency trips at 415 Hz to 425 Hz Underfrequency trips at 390 Hz to 395 Hz Undervoltage time delay (adjustable) Overload circuit trips at any value over 125% rated load capacity. See Para 6,H, (3) for more specific and detailed information regarding overload device. May 31/94 Revised 1-1 Page 11

26 1. Resistor (50 ohm, 100 watt) 9. Voltmeter 2. Resistor (25 ohm, 100 watt) 10. Frequency meter 3. Excitation-deenergization relay 11. Automatic-manual switch 4. Instruction plate 12. Receptacle connector 5. Line selector toggle switch 13. Manual voltage control rheostat 6. Meter selector rotary switch 14. Manual control rectifier 7. AC ammeter 15. Tray 8. Tray fastener Generator Control Tray Figure May 31/94 Revised Page 12

27 b. Memory and time delay module The memory and time delay module (4) is sometimes called the protective monitor module. It is a solid-state device with a hermetically-sealed, reed-type relay. The printed circuit board or card includes five memory circuits and a time delay circuit. Each circuit is connected to a corresponding sensing circuit in the sensing modules (5 and 6). All memory circuits are connected to the module relay coil, and any one of the circuits can energize the coil to open the relay contacts. Thus, when a sensing device energizes any one of the module circuits, the module relay is also energized to break the load contactor holding circuit and allow the load contactor to open. All circuits, except the undervoltage circuit, function immediately to open the load contactor. A time delay system is designed into the undervoltage circuit to prevent nuisance opening of the contactor under conditions of momentary undervoltage in the generator output. An undervoltage condition which continues uninterrupted for a period of 4 to 12 seconds (adjustable) will cause the time delay circuit to open the load contactor. Each of the five circuits is connected to a corresponding indicating light (10, 11, 13, 14 and 15) which is turned on when a fault occurs. The module relay will remain energized (OPEN) and the light will remain ON until the reset switch (7) is pushed to break the module 12-V DC circuit, and allow the relay to return to normal, CLOSED position. c. Indicating lights The function of these lights (10, 11, 13, 14 and 15) is to indicate, to the operator, the abnormal condition of overvoltage, underfrequency, etc., which caused the protective monitor system to function. Each of the five lights is connected to an actuating circuit within the memory and time delay module. When one of the circuits is activated, it turns on the applicable indicating light. The light will remain on until the reset switch (7) is pushed. All lamps in indicating lights may be tested by pressing switch (8). d. Plug-interlock relay The function of the plug interlock relay (1) is to cause the output load contactor to open in the event the cable plug connector becomes accidentally disconnected from the aircraft during power delivery, or if an attempt is made to deliver power when the output cable is not connected to the aircraft. Twentyeight-volt, direct current for operation of the relay is supplied from the aircraft either through an on-board transformerrectifier, or from a twenty-eight-volt, electrical system. Connection from the aircraft to the interlock relay is made through terminals E and F on the output cable plug connector. e. Test-bank switch A spst, toggle switch (18) provides a means of by-passing the interlock relay (1) when supplying power to a load bank or to an aircraft not equipped with a plug interlock system. f. Resistor A 100-ohm, 25-watt resistor (21) is connected in series with the plug interlock relay to protect the relay in the event that phase C contacts in the load contactor should fail to close when the generator ON switch is operated. g. Fuse-interlock relay The function of the fuse-interlock relay (2) is to interrupt the load contactor holding coil circuit and remove the load in case of a blown fuse (17) in the protective relay coil circuit. h. Connector A twenty-six contact connector (19) provides a quick-disconnect facility for all wiring to tray electrical components so that the complete tray assembly may be removed quickly and easily. May 31/94 Revised 1-1 Page 13

28 1. Plug-interlock relay 12. Tray fastener 2. Fuse-interlock relay 13. Overfrequency indicating light 3. Auxiliary underfrequency relay 14. Undervoltage indicating light 4. Memory and time delay module 15. Overvoltage indicating light 5. Over-undervoltage module 16. Load contactor circuit fuse (2-A) 6. Over-underfrequency module 17. Protective system fuse (2-A) 7. Reset switch 18. Test bank switch 8. Light test switch 19. Receptacle connector 9. Hole plug 20. Terminal board 10. Overload indicating light 21. Resistor (100 ohm, 25 watt) 11. Underfrequency indicating 22. Tray Protective Relay Tray Figure May 31/94 Revised Page 14

29 i. Auxiliary underfrequency relay The function of the auxiliary underfrequency relay (3) is to automatically open the excitation-deenergization relay and disconnect the voltage regulator anytime generator frequency drops to 380 Hz or below. This protects the voltage regulator (Fig. 10) and ballast resistors (2, Fig. 7) against overload which could be caused by very high voltage regulator output in its attempt to maintain voltage when the generator is operating at a speed which cannot produce normal voltage output. NOTE: If the auxiliary underfrequency relay is tripped, it will be necessary to momentarily place engine operating mode switch (5, Fig. 9) in BUILD-UP-VOLTAGE position to restore generator voltage. f. Engine Control Panel (See Fig. 9) This panel is mounted directly below the control box. In addition to engine controls and instruments, generator output controls are mounted here. A plexiglass window in the canopy rear door, slants outward at the bottom to form an opening for access to controls when the door is closed. (1) Engine instruments Engine operation is monitored by an ammeter (4), a coolant temperature gage (8), and an oil pressure gage (10). An hourmeter (6) records engine operating time. a. Ammeter The ammeter (4) indicates the direction and value of current flow in the 12-V DC electrical system. Its graduated range is from -60 A through 0 A, to +60 A. b. Temperature gage The temperature gage (8) is a mechanical type of unit construction. It consists of a panel mounted indicating mechanism which is connected by a capillary tube to a bulb mounted in the engine cooling system. The gage indicates engine coolant temperature in the range of 100 o F to 220 o F. c. Oil pressure gage and oil pressure switch The oil pressure gage (10) is a bourdon tube type and indicates engine lubricating oil pressure. It is graduated from 0 PSI to 75 PSI. An oil pressure switch is mounted in a tee fitting directly behind the gage. The switch connects 12-V DC power to the engine control system and to the generator 12-V DC control system when the engine is running. d. Hourmeter The hourmeter (6) is electrically driven from the 12-V DC battery system. The hourmeter measures and records engine running time and will record up to hours on five revolving drums. The hourmeter operates only when the engine is running and the oil pressure switch is closed. e. Fuel gage and blocking diodes An electric fuel gage (2, Fig. 9) accurately indicates the quantity of fuel oil in the tank provided for the generator set. A sending unit mounted in the trailer or truck mounted unit fuel tank supplies the signal to the gage. Twelve-volt DC operating power is supplied to the fuel gage from two sources. The gage functions when the engine is running, or when the instrument lights are ON. Since two power sources are connected to the fuel gage system, a blocking diode (18) is required in each power source circuit. One diode prevents energizing the motor-generator control circuit when panel lights are ON. Another diode prevents operation of the panel lights by the engine-generator circuit when the engine is running. To check fuel quantity when engine is stopped, use switch (3) to turn ON panel lights. May 31/94 Revised 1-1 Page 15