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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. Index Terms--Generator ground fault protection, generator grounding, ground fault protection, grounding, stator iron damage.

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. Index Terms--Generator ground fault protection, generator grounding, ground fault protection, grounding, stator iron damage.

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. Index Terms--Generator ground fault protection, generator grounding, ground fault protection, grounding, stator iron damage.

Variable speed ac drives are finding their way into all types of industrial and commercial power system applications. Their application to the load (motor) generally is reasonably well selected - at least within heavy industry. However, there are many line (source) design parameters learned in the 1950's and 1960's which are now being frequently overlooked. This paper represents many years of experience doing power quality investigations. The authors combined this experience with recent technology and discuss some of the areas of concern which frequently result in serious performance or power quality problems. Finally, basic design guidelines are given to greatly minimize system problems - especially as newer technologies are intermixed with old.

This paper addresses electrical distribution system problems that affect the reliability of power to oil-field pump motors and support loads. An off-shore oil facility is used as an example. Field measurements at numerous platforms were conducted and subsequently analyzed to evaluate power quality concerns. A power system study was completed off-site to provide computer simulation of the electrical system under numerous operating conditions. Electrical considerations include fault current calculations, protective relay coordination, load flow, harmonic analysis, transient stability, and motor starting. The principal results of this work were a series of recommendations involving operations changes and/or adding conventionally available hardware borrowing from other industry experiences. Index Terms--Coordination, grounding, load flow, motor failures, motor starting, off-shore electrical distribution, power quality, transient stability.

Modern sodium chlorate or sodium hypochlorite-making processes (commonly known as “bleach”) take salt and water through an electrolytic process. The electrolytic process requires a significant amount of dc power. Bleach production plants, equipped with rectifiers, can generate potentially damaging harmonic currents if not mitigated or controlled. This paper presents a combination of harmonic mitigation methods applied at a large bleach production facility. The harmonic mitigation methods consisted of transformer phase shifting and multistage harmonic filter banks applied at 34.5 kV to satisfy IEEE Standard 519-1992 harmonic distortion limits at the point of common coupling. The authors faced several challenges with the harmonic filter design that included various operating conditions within the facility as well as numerous utility substation loading and capacitor combinations. [ABSTRACT FROM AUTHOR]

Switching transients associated with circuit breakers have been observed for many years. Recently, this phenomenon has been attributed to a significant number of transformer failures involving primary circuit-breaker switching. These transformer failures had common contributing factors such as the following: 1) primary vacuum or SF-6 breaker; 2) short cable or bus connection to transformer; and 3) application involving dry-type or cast-coil transformers and some liquid-filled ones. This paper will review these recent transformer failures due to primary circuit-breaker switching transients to show the severity of damage caused by the voltage surge and discuss the common contributing factors. Next, switching transient simulations in the electromagnetic transients program will give case studies which illustrate how breaker characteristics of current chopping and restrike combine with critical circuit characteristics to cause transformer failure. Design and installation considerations will be addressed, particularly the challenges of retrofitting a snubber to an existing facility with limited space. Finally, several techniques and equipment that have proven to successfully mitigate the breaker switching transients will be presented, including surge arresters, surge capacitors, snubbers, and these in combination. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]