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Protective relays
Protective relays,1922

Protective relays
Their theory, design, and practical operation
By Victor H. Todd
McGraw-Hill book company, Inc. , 1922






In preparing a work of this nature, it will be realized that the subject is so broad and varied in its scope as to preclude an author's intimate personal knowledge of each and every system described. Attempt has been made to cover the subject the first principles of Protective Relays to the protection of high tension net-works, the object being to make the work of value not only to the operator and tester who has a fair knowledge of electricity and is seeking more information, but also to the designer of the system who may find many points not previously
taken into consideration in his calculations.
Consequently, many reliable sources of information were freely consulted and in several instances, passages were quoted verbatim a booklet entitled "Performance of Instrument
Transformers" and "Protective Relays" which in turn was reprinted an article by Mr. L. N. Crichton in The Electric Journal. Full credit is hereby given to the Westinghouse Electric & Manufacturing Company for such excerpts; also to the American Institute of Electrical Engineers for several paragraphs quoted its June, 1919, Proceedings.
Some of this material has been published in the form of articles by the author in Power, Power Plant Engineering, Electrical Record and Southern Engineer, and thanks are hereby given to their editors for permission to use the text and electro-types for illustrations.
The author also wishes to extend his thanks and appreciation to Mr. F. A. Annett, Associate Editor of Power, for personal interest and assistance in the preparation of the work; to Mr. L. N. Crichton, Relay Engineer of the Westinghouse Electric & Manufacturing Company, and writer of several articles which much valuable information was obtained, who kindly read this manuscript, and offered many helpful  suggestions and constructive criticisms; and to officials of the Westinghouse Electric & Manufacturing Company, the General Electric Company and the Condit Electric Company, for valuable assistance in procuring photographs for illustrations.

Contents

Prefacev
Chapter I
What are Protective Relays
Early SystemsFire RisksInsulated FusesObjectionsAutomatic SwitchesDefinitionReasons for RelaysRequirements SavingsPrinciples of OperationNomenclature.
Chapter II
Circuit Breakers and Releases
ClassesPrinciples of OperationAdjustmentShunt-trip AttachmentUnderload ReleaseUndervoltage ReleaseOvervoltage ReleaseWhy Releases are not Always Sufficient.
Chapter III
Trip Circuits and Time Delays
Object of TripTrip Circuit SourcesShunt TripAuxiliary ContactsCircuit Opening or Series TripObjectionsTransfer RelaysTime DelaysClassificationsInverse-time LimitDefinite TimeInverse-definite TimeHow Time Delays are Obtained.
Chapter IV
Plunger-type Protective Relays
Various FormsAdjustmentsMore FormsDefinite-time Relay Bellows-typeObjectionsSimple System Typical A.C. Plunger-typeIllustration of SettingRelays Required More Bellows TypesOil Dashpot TypesLimitationsDefinite-timeTripping Sources.
Chapter V
D.C. Power-directional Relays
Necessity of this TypeD'Arsonval TypeUsed as Excess-current RelayPolarized TypeMoving Iron TypeBusbar Types.
Chapter VI
Applications of D.C. Power-directional Relays
Limitations to UseStorage Battery ProtectionOther Methods Standby BatteriesFailure of Prime MoversLoss of Field ProtectionParallel Feeders on D.C.Ring System on D.C.Wider ApplicationsUndercurrent ProtectionOvervoltage ProtectionUndervoltage Protection.
Chapter VII
Induction-type Current Relays
DevelopmentTypical RelaySettingsTorque CompensatorTime DelaysContinuity of Trip IndicatorInduction vs.  Solenoid-plunger RelaysRelay ContactsLoad on TransformerRelay Specifications.
Chapter VIII
A.C. Power-directional Relays
Early developmentMost Common UseOverload and Reverse-current RelaysObjections and FailingsLatest DevelopmentsThe Contactor SwitchThe Torque CompensatorStray Field EffectOther TypesDifferential Power-directional Relay
Chapter IX
Characteristics op A.C. Disturbances
Important PointsEffects of OverloadNature of Short-circuits on Transmission LinesCalculation of the Short-circuit Currentnator and Transformer ConstantsEffect of Low VoltageEffect of Unbalanced Short-circuitsCharacteristics of Relays.
Chapter X
Instrument Transformers and Groupings
Current and Voltage TransformersInherent ErrorsRatio EirorMagnetization of CoreEffect of Secondary LoadOther Sources of ErrorSingle-phase GroupingsTwo-phase GroupingsNecessity for Three Transformers on Three-phaseAdvantages of the Z-connectionOpening of SecondaryVoltage  TransformersVarious ErrorsPolyphase GroupingsLoad on TransformersUse of Both Current and Potential Transformers
Connections to Watt RelayStar-delta  ConnectionDetermining Phase Rotation.
Chapter XI
Protection op Motors, Transformers, Generators and Lines
Protection of MotorsSettingsTwo-phase ProtectionThree-phase ProtectionProtection of Synchronous 
MotorsProtection of Rotary ConvertersTransformer ProtectionProtection in BanksPower-directional Relay ProtectionOther Differential MethodsPolyphase Transformer ProtectionsProtecting Three-phase Star-delta BanksProtection of GeneratorsProtection by Power-directional RelaysProtection of Single LinesProtection
Against Grounds.
Chapter XII
Protection of Parallel Feeders
ObjectsVarious MethodsInverse-time-limit DiscriminationBalanced Protection SystemDifferential Balance Relay ProtectionSplit-conductor SystemThe Pilot Wire SystemProtection by Power-directional RelaysCross-connected Power-directional RelaysDifferential Power-directional or Double-contact RelaysDisadvantages of Cross-connected Systems.
Chapter XIII
Protection op Radial Ring and Network Systems
Simple Radial SystemSelecting the Proper RelayLimit of  DivisionsThe Ring SystemTime SettingsParallel Feeders on RingRings with More than One SourceProtection of  NetworksThe Under voltage and Excess-current System.
Chapter XIV
Miscellaneous Relays
Over and UndervoltageUndercurrentOverload TelegraphReversed PhasesService-restoring RelaysInteresting  OscillogramsBell-ringing RelaysD.C. Temperature RelaysA.C. Temperature RelaysRelay SwitchesTransfer RelaysHigh-tension RelaysTiming Relays with a Cycle CounterPrinciple of Cycle CounterTiming a Circuit-closing RelayTiming a Circuit-opening RelayTiming the Breaker or Oil Switch
Typical Layout.
Chapter XV
Testing Direct-current Relays
Ground-testingTesting Relay SwitchesVarious Loads and Testing SourcesTesting Millivolt-type RelaysTesting Plunger-type RelaysTesting Time-limit RelaysCurves and TablesConclusions.
Chapter XVI
Testing nating-current Relays
Reasons for TestingRelays Requiring Current OnlySourcesRheostatsPhantom LoadsStandardsCurrent Transformers Trip CircuitsTiming the RelayAn Actual TestThe Cycle CounterMaking the AdjustmentAdditional PrecautionsTesting Voltage RelaysPower-directional RelaysReverse-phase RelaysTemperature RelaysConclusion.
Chapter XVII
Locating Faults in Feeders and Wiring
Most Common FaultsApparatus RequiredTesting for Opens, Shorts or GroundsAccurately Locating the Short-circuitLocalizing a GroundCalculating the LocationTwo-ammeter MethodThe Fault LocalizerL and N Power BridgeBurning out the Fault.
Index

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