Louie J. Powell

The impact of system grounding practices on generator fault damage

Industry has recently become sensitized to the problem of severe generator damage due to stator ground faults. To prevent this damage, it has been suggested that the practices employed for neutral grounding should be changed. This paper provides an analytical perspective on this problem and suggests that the real issue is the manner in which the neutral of the generator itself is grounded.

Influence of Third Harmonic Circulating Currents in Selecting Neutral Grounding Devices

It has long been recognized that third harmonic currents can and often do appear in the neutral of industrial generators. This paper will review the causes of such currents and the effects these currents have in the power system. The common methods of neutral grounding will be discussed with regard to circulating harmonic currents.

Grounding and ground fault protection of multiple generator installations on medium-voltage industrial and commercial power systems - Part 3: Protection Methods Working Group Report

This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material.

Current Transformer Burden and Saturation

A tutorial review of the steady-state and transient behavior of current transformers used with power system relays and meters is presented. ANSI accuracy standards are discussed and consideration is given to the significance of burden and saturation in the application of protective relays.

An industrial view of utility cogeneration protection requirements

Most electric utilities have adopted a set of standardized requirements for protection at the interface with a cogenerating industrial system. Typical utility requirements are reviewed, the basis for their formulation is explained, and practical ways for the industrial cogenerator to satisfy them are suggested. The discussion covers engineering planning, fault detection, islanding, dead circuit pickup, and manual synchronization. >

Grounding and ground fault protection of multiple generator installations on medium-voltage industrial and commercial power systems - Part 1: The problem defined Working Group Report

This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material.

Grounding and ground fault protection of multiple generator installations on medium-voltage industrial and commercial systems-Part 2: Grounding Methods Working Group report

This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material.

Grounding and ground fault protection of multiple generator installations on medium-voltage industrial and commercial power systems - Part 4: Conclusion and Bibliography Working Group Report

This paper discusses typical grounding practices and ground fault protection methods for medium-voltage generator stators, highlighting their merits and drawbacks. Particular attention is given to applications of multiple generators connected to a single bus. The paper also provides an overview of the generator damage mechanism during stator ground faults. Problem areas associated with each type of grounding are identified and solutions are discussed. The paper also provides a list of references on the topic. The paper is intended as a guide to aid engineers in selecting adequate grounding and ground fault protection schemes for medium-voltage industrial and commercial generators for new installations, for evaluating existing systems, and for future expansion of facilities, to minimize generator damage from stator ground faults. These topics are presented in four separate parts, Parts 1-4. Part 1 covers scope, introduction, user examples of stator ground failure, and theoretical basis for the problem. Part 2 discusses various grounding methods used in industrial applications. Part 3 describes protection methods for the various types of grounding and Part 4 provides a conclusion and bibliography of additional resource material.

Risks From Utility Supply Disruption

This article elaborates on the properly required protection and how its operation will prevent the undesired consequences to the ICG owner, the utility, and the general public. This article also discusses actions that take place when the utility supply is disrupted, creating an islanding condition and states reasons why protection required by regulatory agencies, local utilities, and documents such as IEEE Standard 1547 IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems are required of an individual ICG. Consequences of not having the protection in place can damage the generator and/or its prime mover plus be a hazard to public safety. Examples of these consequences are given. This article will provide a clearer understanding to ICG owners of why they are required to have specified protective equipment in place.

Application of Protective Relays on a Large Industrial-Utility Tie with Industrial Cogeneration

The recent emphasis on the simultaneous production of electric power and steam within the confines of the industrial plant, often utilizing waste products from the industrial process as fuel, has resulted in renewed interest in the problems of applying protective relaying at the interface between the cogenerating industrial facility and the electric utility. This paper will review the considerations that must be taken into account at the consumer-utility interconnection and will suggest protective practices for these tie points.