Digital Protective Relays: Problems and Solutions

Digital (microprocessor-based) protection relays (DPR) are dominating the global market today, essentially pushing all other types of relays out of the picture. These devices play a vital role in power operations for fields ranging from manufacturing, transportation, and communication to banking and healthcare.

Digital Protective Relays: Problems and Solutions offers a unique focus on the problems and disadvantages associated with their use, a crucial aspect that goes largely unexamined. While there is already a massive amount of literature documenting the benefits of using digital relays, devices as sophisticated as DPR obviously have faults and drawbacks that need to be understood. This book covers these, delving into the less familiar inner workings of DPR to fill a critical literary void and help decision makers and specialists in the field of protection relays find their way out of the informational vacuum. The book provides vital information to assist them in evaluating relay producers' claims and then choose the right product.

Tearing away the informational "curtain" that exists today, this book:

Describes construction of functional modules of existing relays
Analyzes drawbacks and problems of digital relays
Details specific technical problems and their solutions
Assesses dangers of intentional destructive electromagnetic intrusions
Discusses alternative (non-microprocessor-based) protection relays, and problems related to international standards
Focusing on practical solutions, this book explains how to correctly choose digital relays and ensure their proper use while avoiding the many problems they can present. The author avoids mathematics and theory in favor of more practical, tangible information not easily found elsewhere. Setting itself apart from other books on the subject, this volume shines a light into the long hidden "black box" of information on DPRs, giving users a valuable tool to help them anticipate possible problems, something sorely lacking in the literature.

Basic Components of Digital Protective Relays

Semiconducting Materials and the p-n Junction

The Principle behind Transistors

Some Transistor Kinds

General Modes of the Bipolar Transistor

Transistor Devices in Switching Mode

Thyristors

Optocouplers

Electromagnetic Relays

Design and Functional Modules of Digital Protective Relays

Overall Structure and Design of Digital Protective Relays (DPRs)

Analog Input Modules

Output Relay Modules

Digital (Logic) Input Modules

Central Processing Units (CPU)

Internal Power Supplies

Problems with the Reliability of Digital Protective Relays

Reliability Myth

The Real State of Affairs with DPR Reliability

What to Do with All These Problems?

"Intellectualization" of Protective Relays: Good Intentions or the Road to Hell?

Logic Inputs in Digital Protective Relays

Reliability of Logic Inputs in DPRs

Increasing Noise Immunity of the Logical Inputs in DPRs

Problems with Output Electromechanical Relays

The Analysis of Actual Operating Conditions of the Output Relays in Digital Protective Relays

Analysis of the International Standards and Technical Specifications

Improvement of DPR Output Circuits

Problems with External Power Supplies

Electromagnetic Disturbances in the Power Network

Applying Uninterrupted Power Supply

Other Problems in the AC Network

Problems in DC Networks

Testing Digital Protective Relays

Problems with DPR Testing

New View on the Problem

Modern Test Systems for Digital Protective Relays

Modern RPTS Problems

Offered Solutions

Digital Rate of Change of Frequency Relays, and Problems in Testing It

Electromagnetic Intrusions on Digital Protective Relays

Electromagnetic Vulnerability of DPRs

Lightning Strikes

Switching Processes and Electromagnetic Fields Generated by Operating Equipment

Issues with Control Cables Shielding

Distortion of Signals in the Current Transformer Circuits

Optical-Electronic Currents and Voltage Transformers

The Harmonics Impact on the Measured Current and Voltage on DPRs

The Quality of Voltage in the Supply Mains

Intentional Destructive Electromagnetic Impacts

Alternative (Nondigital) Protective Relays

Universal Overcurrent Protective Relays

Reed Switches Are New Perspective Elements for Protective Relays

Polarized and Memory Reed Switches

Power Reed Switches

Overcurrent Protective Relays with Reed Switches

Simple, Very-High-Speed Overcurrent Protection Relays

Reed-Based Devices For Overcurrent Protection of HV DC Equipment

The New-Generation Universal-Purpose Hybrid Reed: Solid-State Protective Relays

Problems with International Standards

The Basic International Standard on Electromechanical Relays (IEC 61810-1)

The International Standard on Solid-State Relays (IEC 62314-1)

The International Standard on Reed Switches (IEC 62246-1)

New Concepts for DPR Design

Index

Vladimir Gurevich is with the Israel Electric Corporation in Haifa, Israel.

RECENZII

Spune-ne opinia ta despre acest produs!

scrie o recenzie