Prafulla Pillai

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.

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.

Switching transient analysis and specifications for practical hybrid high resistance grounded generator applications An IEEE/IAS working group report #2

This paper reports on the continuing efforts of an IAS Working Group to investigate industry concerns with excessive stator fault-point burning damage in conjunction with various industrial generator grounding and ground fault protection practices. Previous working group efforts were reported in a series of papers discussing typical voltage bus connected industrial generator applications. These papers proposed a new method of grounding, called hybrid grounding, that offered the ability to limit damage while still providing the required level of ground fault current under all operating conditions. This new Working Group paper reports on the detailed design requirements for hybrid grounding. The paper reports the results of switching transient studies that formed the bases for recommended overvoltage protection. It also provides guidance in selection of equipment and fault protection required for hybrid grounding. The experience gained with several hybrid grounding applications is also reported.

Commissioning and maintenance testing of multifunction digital relays

Protective relay technology over the past twenty-five years has evolved from single-function electromechanical (E-M) relays to static (electronic) relays and finally to digital multifunction relays. A significant number of these multifunction digital relays are being installed on medium voltage electric power systems within industrial and commercial facilities. As was required in earlier E-M and static relay technologies, digital relays also require commissioning and relay setting verification. This paper discusses the unique challenges the user faces in testing and commissioning digital multifunction relays. It also explores the impact on maintenance testing of self-diagnostics, the digital relay¿s internal capability to check itself for failures.

Switching transient analysis and specifications for practical hybrid high resistance grounded generator applications An IEEE/IAS Working Group report #2

This paper reports on the continuing efforts of an IAS Working Group to investigate industry concerns with excessive stator fault-point burning damage in conjunction with various industrial generator grounding and ground fault protection practices. Previous working group efforts were reported in a series of papers discussing typical voltage bus connected industrial generator applications. These papers proposed a new method of grounding, called hybrid grounding, that offered the ability to limit damage while still providing the required level of ground fault current under all operating conditions. This new Working Group paper reports on the detailed design requirements for hybrid grounding. The paper reports the results of switching transient studies that formed the bases for recommended overvoltage protection. It also provides guidance in selection of equipment and fault protection required for hybrid grounding. The experience gained with several hybrid grounding applications is also reported.