DOCUMENT RESUME ED 269 643 CE 044 494 TITLE Electrical Power Station Theory. A Course of Technical Information for Electrical Power Station Wireman Apprentices. Revised Edition. INSTITUTION Lane Community Coll., Eugene, Oreg. SPONS AGENCY Oregon State Dept. of Education, Salem. PUB DATE 86 NOTE 195p.; For related documents, see CE 044 493 and CE 044 496. PUB TYPE Guides Classroom Use reterials (For Learner) (051) EDRS PRICE MF01/PC08 Plus Postage. DESCRIPTORS *Apprenticeships; Electric Circuits; Electric Motors; Electronics; *Equipment Maintenance; Industrial Education; Instructional Materials; Postsecondary Education IDENTIFIERS *Electric Power Generation ABSTRACT This third-year course for electricalpower station wirer apprent4,:es is a foundation for the study ofall aspects of installation and maintenance e. power station equipment.It also provides a good technical backgroundas well as the general knowledge essential to power station operator trainees. Thecourse is intended to be equivalent to a classroom :ourse requiringa minimum of 5 hours of class attendance each week for 36 weeks. Theseven units consist of one to six lessons each. Unit topics includecare and maintenance of electric motors and generators, insulating materialsfor electrical machinery, electrical drawings, switchesand circuit breakers, protective devices and relays, insulating oil,system voltage regulation and power capacitors, and control electronics. Each lesson provides a brief rationale for the contentto be learned, lists directions, cites the required reference,lists check-up questions, and provides information sheets. (YLB) **************1******************************************************** * Reproductions supplied by EDRS are the best thatcan be made * * from the original document. * ***************************************************A***************,-*** "PERMISSION TO REPRODUCE THIS U.S DEPARTMENT OF EDUCATION MATERIAL Ht.S BEEN GRANTED BY of Educational Research end Improvement RONAL RESOURCES INFORMATION CENTER IERICI ITIV Thisdocument has been rprcduc,d es received from the person or orgenizahon originating it ID Minor changes have been made to improve reproduction is ,siity TO THE EDUCATIONAL RESOURCES Points &view or OP wins Milted in th's doCu. INFORMATION CENTER (ERIC)." TOM do not necessanly represent official S, OERI position or policy ge d r s e d, ELECTRICAL POWER STATION THEORY A Course of Technical Information for Electrical rower Station Wireman Apprentices T ACKNOWLEDGEMENT This project was developed under a subcontract from the Oregon Department of Education by Apprenticeship program at Lane Community College, Eugene, Oregon. STATEMENT OF ASSURANCE It is the policy of the Oregon Department of Education that no personbe subjected to discrimination on the basis of race, national origin, religion, sex, handicap or marital status in any program, service oractivity for which the Oregon Department of Education is responsible. TT PREFACE This third-year course for electrical power station wireman apprentices is a foundation for the study of all aspects of installation and maintenance of power station equipment. It does not cover in detail all the devices utilized in design, construction, or operation. It is felt that manufac- turers' literature on specific equipment will serve as an adequate source for such details. To assure maximum continuity of electrical service with minimum damage to life and property, the equipment in our modern electrical power systems has become more and more sophisticated. Substations frequently become com- plex nerve centers and may be found in large and small systems, in power company and industrial installations. Wide usage of electrical energy and high demand for reliable operation have created a need for trained personnel who are qualified to be directly responsible for the installation, operation, and maintenance of equipment. Power Jtation operator trainees will also find that this basic course provides a good technical background as well as the general knowledge so essential to understand the work performed on the job. The course is intended to be equivalent to a classroom course requiring a minimum of five hours of class attendance each week for 36 weeks of the year. TTT CONTENTS TITLE PAGE I ACKNOWLEDGEMENT AND STATEMENT OF ASSURANCE II PREFACE III UNIT I: A. CARE AND MAINTENANCE OF ELECTRICAL MOTORS A GENERATORS 1-10 B. INSULATING MATERIALS FOR ELECTRICAL MACHINERY... ... 11-12 UNIT II ELECTRICAL DRAWINGS Circuit Diagrams Used in Controller Work 14-15 One-Line Diagrams 23 Elementary Diagrams and Control Schematics 36 Wiring (Connection) Diagrams 58 Electrical Print Reading 65 Schematics for Motor-Operated Disconnects Sectionalizing Station 69 UNIT III SWITCHES AND CIRCUIT BREAKERS Fundamentals of Circuit Interruption 74 Circuit Breaker Mechanisms 81 Maintenance of Circuit Breakers 97 UNIT IV PROTECTIVE DEVICES AND RELAYS Protective Relays 103 UNIT V INSULATING OIL Transformer Oil Care and Mairicenance 135 UNIT VI SUSTEM VOLTAGE REGULATION AND POWER CAPACITORS A-C Voltage Regulators 137 Step Voltage Regulators 146 Power Capacitors 157 (more) ELECTRICAL POWFR STATION THEORY UNIT I A. CARF AND MAINTENANCE OF ELECTRICAL MOTORS AND GENERATORS B. INSULATING MATERIALS FOR ELECTRICAL MACHINERY INFORMATION SHEET NO. 1 CARE AND MAINTENANCE OF ELECTRIC&L MOTORS ANDGENERATORS Motors and generators ordinarily found in power stationsart.! substations do not demand extraordinary care to keep them operatingefficiently. Like all machines, they should receive planned attention. A rehular system of examining, adjusting, and servicing will certainly paydividends. It is highly desirable that you know how to tell when a motor or genera- ta%r has failed or needs some minor repair oradjustment. All types of motors and corresponding generators have many elements in commonfor which mainte- nance work is fairly uniform item for item. Too often motor maintenance is considered ahandyman's job that almost anyone can do without experience or craining. This concert has led to many failures, expensive production delays, high repair costs, unnecessary motor replacements, broken shafts, poor working tools, and employee injuries. No one would expect an rotomobile to runyear-after-year without proper inspec- tion or to run with just any kind of oil in the crankcase; yetthis is the kind of treatment that many electric motors receive. Heie are some important rules for preventive maintenanceof rotating equipment: Keep it clean. Keep it properly lubricated. Don't wait for a motor to smoke or squeak before oiling or other maintenance. Don't continuously overload. Correct poor conditions before motor fails. Remember an ounce of prevention is better than apound of cure. REMEMBER, it is cheaper to take care of motors than to replacethem. A simple lubrication job will sometimes clear up symptoms ofdistress which are taken for much more serious troble. When an apparently good motor starts to act up, look first at the lubrication. ENEMIES OF AN ELECTRIC MOTOR Dust Excessive oil Moisture Condition of insulation Friction Misalignment Vibration Overload Lai,: of lubrication 2 Dust Dust is probably motor enemy number one. It is eternally getting into the motors and settles on housings, windings, frame, slip rings, commutators, and bearings. On windings, dust acts as an added layer of heat insulation. Dust stops the ventilation ports. It acts as an abrasive and insulator on slip rings, commutators, and bearings. On windings, dust acts as an added layer of heat insulation and impairs ventilation. It acts as an abrasive and insulator on slip rings and commutator; inside a bearing it will ruin it. The time to eliminate dust inside a motor is before it has had a chance to unite with moisture or oil. Thus, it is necessary to wipe off motors and to blow the dust out of the winding at regular intervals. Compressed air up to about forty pounds of pressure may be used. This air should be dry and must not contain grit or metal. Excessive Oil Oil inside bearings is the life blood of motors. Oil outside of bear- ings is poison to electric motors. Dust plus oil forms gum. Gum nr oil on a commutator au....8 for poor operation. The faces of the brushes become glazed, and harmful sparking follows. Gum or oil on the windings is even more harmful. Once the winding is thoroughly soaked with dirty oil, the motor is in danger of a turn out or breakdown. Oil plus dust on windings limits the ventilation and holds stray metallic particles, thus further lowering the insulation values. When oil and dust have been allowed to build up on a motor insulation, it can be removed by use of scrapers, rags, or a solvent such as electrolene. Solvents should be used with caution and care taken not to soak the insula- tion or it may be softened. When through cleaning, dry the windings and apply a coat of insulating varnish if necessary. The room should be vtnti- late(' when washing a motor. It is imperative that oil be kept away from windings. Wipe off stray oil; don't lubricate sleeve bearings while the motor is running or overfill them with oil. Moisture An ideal operating location for a motor is a dry place.Since this is often impractical the best practice is to dry a motor as quickly as possible after it gets wet. This is important for two reasons. First, it takes time for moisture to soak in and soften the insulation. Thus, if the moisture can be removed in a hurry, little damage will be done. Second, water that is left on the insulation surface will absorb harmful compounds from the air, such as alkalies and salts, and may thus become a destructive agent. 3 Every effort should be made to keep water fromdripping, splashing, or flooding a motor. A motor may be dried out by - a. Placing it in an oven. b. Circulating current through the windings with motorblocked. c. Using a fan to force hot air through the windings. G. Cover motor with a tarpaulin leaving a hole atthe top and then heat the inside with resistors or light bulbs. e. Any combination of the above. Occasional megger readings should be taken duringdrying. Maximum temperature should normally be below the boiling pointof water.