Engineering Book from C.H.I.P.S.

Electric Relays
Principles and Applications
by Vladimir Gurevich

Electric Relays focuses on the operational and functional aspects rather than on theory and mathematics.


  • Provides a comprehensive survey of the entire range of electric relays with a focus on the practical aspects
  • Develops a deep understanding of the design, operation, and applications of relays and their major components
  • Covers the entire "world of electrical relays," from reed switch, solid-state, and high-voltage relays to distance, frequency, and microprocessor-based relays
  • Includes abundant illustrations, references, and a complete glossary of terms



  • Relays and Horses
  • From Oersted to Henry
  • Art Professor Samuel Morse
  • Edison's Relay
  • The First Industrial Relays

Magnetic Systems of Elecromagnetic Neutral Relays

  • Basic Components of Electromagnetic Relays
  • Hysteresis and Coercitive Force
  • Types of Magnetic Systems
  • Differences Between AC and DC Relays
  • Some Auxiliary Elements for Improving the Relay Operation
  • What Happens When a Relay is Energized
  • Windings of Relays: Types and Design Features

Contact Systems

  • Designs of Basic Types of Contacts
  • Silver, Gold, Platinum
  • Contacts with Two-Stage Commutation
  • What is the Purpose of ''Contact Pressure?''
  • Self-Cleaning Contacts
  • Self-Adjusting Contacts
  • When Power Does Not Equal Multiplication by Current and Voltage
  • Split Make-Before-Break. High-Frequency Contacts
  • Compensation for Shocks and Electro-Dynamic Forces in Contacts
  • Sparking Contacts and Their Control
  • High-Power Contact Systems
  • Mercury Displacement Relays

External Design of Relays

  • Environmental Impact on Relays
  • Wood and Cardboard: First Protection Shield for Relays
  • Is a Sealed Relay Always Better Than Open One?
  • Outlets, Terminal Sockets and ''Containers'' for Relays
  • Indicators of Operation and Test Buttons
  • Relays Which Do Not Look Like Relays at All

Reed Switches and Reed Switch Relays

  • Who invented the ''Reed Switch''?
  • Coruscation of Ideas and Constructions
  • High Power Reed Switches
  • Membrane Reed Switches
  • Mercury Reed Switches
  • High-Voltage Reed Switches
  • Reed Switches with Liquid Filling
  • Polarized and Memory Reed Switches
  • Reed Switch Relays
  • Mercury Reed Switch Relays
  • Winding-Free Relays

High-Voltage Relays

  • What is a ''High-Voltage Relay?''
  • Open Relays for High-Voltage Switching
  • Vacuum and Gas-Filled High-Voltage Low Power Relays
  • High Power Vacuum Relays and Contactors
  • High-Voltage Reed Relays
  • High-Voltage Interface Relays

Electronic Relays

  • Was it Thomas A. Edison Who Invented a Vacuum Light Lamp?
  • Lee De Forest Radio Valve: From its First Appearance Until Today
  • How a Vacuum Tube Works?
  • Relays with Vacuum Valves
  • Gas-Tubes with Relay Characteristics
  • Power Mercury Valves
  • Electron-Beam Switching Tubes
  • Semiconductor Relays
  • Optoelectronic Relays
  • Super-Power Electronic Relays
  • Hybrid Relays

Time Relays

  • Electromagnetic Time-Delay Relays
  • Capacitor Time-Delay Relays
  • Relays with Clockwork
  • Pneumatic and Hydraulic Time-Delay Relays
  • Electronic Time-Delay Relays
  • Attachments to Standard Electromagnetic Relays
  • Microprocessor Based Time-Delay Relays
  • Accelerated (Forced) Relays

Thermal Relays

  • Relays Based on a Bimetallic Thermal Element
  • Protective Thermal Relays
  • Automatic Circuit Breakers with Thermal Elements
  • Dilatometer Relays
  • Manometric Thermal Relays
  • Mercury Thermal Relays
  • Thermal Relays with Reed Switches
  • Semiconductor Thermal Elements and Thermal Relays

Protective Current and Voltage Relays

  • What are ''Protective Relays''
  • Current and Voltage Transformers
  • Instantaneous Current and Voltage Relays
  • Current Relays with an Independent ''Time-Delays'
  • Current Relays with Dependent Time-Delay
  • Harmonic and Voltage Restraint Relays
  • Pulse Current Relays

Power and Power-Directional Relays

  • Induction-Type Relays
  • Characteristics of Power Direction Relays
  • Electro-Dynamic-Type Relays
  • Electronic Analogs of Power Direction Relays

Differential Relays

  • Principles of Differential Protection
  • High-Impedance Differential Relays
  • Biased Differential Relays
  • Electromagnetic Percentage Differential Relays
  • Induction-Type Differential Relays
  • Harmonic Restraint Differential Relays
  • Pilot-Wire Differential Relays

Distance Relays

  • Principles and Basic Characteristics of Distance Protection
  • System Swing
  • Principles of Distance Relays Construction
  • Why do Distance Relays Need ''Memory?''
  • Distance Relays with Higher Performance
  • Electronic Analogs of Impedance Relays

Frequency Relays

  • Why is it Necessary to Control Frequency in Electric Networks?
  • Charles Steinmetz: Inventor of the Frequency Relay
  • Induction Frequency Relays
  • Resonance Relays
  • Electronic Frequency Relays

Microprocessor-Based Relays: Prospects and Challenges

  • Is It a Relay at All?
  • Advantages of Microprocessor-Based ''Relays'
  • Disadvantages of Microprocessor-Based ''Relays''

Special Relays

  • Polarized Relays
  • Latching Relays
  • Sequence Relays
  • Rotary Relays
  • Moving-Coil Relays
  • Amplifier-Driven Relays
  • Magneto-Hydro-Dynamic Relays
  • Annunciator Target Relays
  • Flashing-Light Relays
  • Buchholz Relays
  • Safety Relays
  • Ground Fault Relays
  • Supervision Relays
  • Hydraulic-Magnetic Circuit Breakers


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Electric Relays
Principles and Applications
by Vladimir Gurevich

2005 704 pages $175.95 + shipping
Texas residents please add 6.75 % sales tax

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