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Chipper motors in pulp and paper mill environment are of special design—the stability on impact loads is one important consideration. The power factor under normal operation will continuously swing due to varying loads. This paper describes the guesswork-free rigorous calculations of pull-out (out-of-step) power factor based on the parameter of an actual installation. Single phasing is rather a rare occurrence; however, such an event has been experienced in an installation due to overheating and arcing at the fuse clips in a NEMA E2 starter of a chipper motor. Discussions on the single-phase protection of synchronous motors and recommended settings are provided. [ABSTRACT FROM AUTHOR]

This paper demonstrates that, in a multi-voltage-level (medium and low voltages) distribution system, the incident energy can be reduced to 8 \cal/\cm^2 (hazard risk category 2) or even less, so that a personal protective equipment outfit of greater than two is not required. This is achieved with the current state-of-the-art equipment and protective devices. It is recognized that, in the existing distribution systems, not specifically designed with this objective, it may not be possible to reduce the arc-Flash hazard to this low level, unless major changes in the system design and protection are made. A typical industrial distribution system is analyzed, and tables and time-coordination plots are provided to support the analysis. Unit protection schemes and practical guidelines for arc-Flash reduction are provided. The methodology of IEEE 1584 is used for the analyses. Reducing HRC also reduces the fault damage to the equipment. [ABSTRACT FROM AUTHOR]

The industry is heading toward innovations in the electrical system designs, equipment, and protection to limit the arc flash hazard. This paper demonstrates that, in a multi-voltage-level (medium and low voltages) distribution system, the incident energy can be reduced to 8 \cal/cm^2 or even less [hazard risk category 2] so that a personal protective equipment outfit that is greater than two is not required. This can be achieved with the current state-of-the-art equipment and protective devices. This paper has two parts: part 1 is for the methodology, and part 2 is for the analysis. There are variations in the calculation results, depending upon the calculation methods. A new method for the calculation of the energy accumulation to account for the decaying nature of the short-circuit currents is presented. [ABSTRACT FROM AUTHOR]

Industrial distribution systems have been designed in the USA, considering prevalent standards, i.e., American National Standards Institute (ANSI), IEEE, National Electrical Code (NEC), Occupational Safety and Health Administration (OSHA), etc., and arc flash was not a consideration for designing electrical power systems in the industry. Functionality and economics were the important factors, and will always be so. However, the arc flash analysis and limiting the incident energy will usher a new parameter in system design. It can be demonstrated that in many current installations and new installations designed without considerations of limiting the arc flash energy, the hazard risk category exceeds the highest Class 4 personal protective equipment (PPE), i.e., an arc thermal performance exposure value (ATPV) of 40 cal/cm². This paper discusses typical industrial distribution systems at low-voltage and medium-voltage levels and demonstrates the impact of system design decisions and protection on the incident energy and arc flash hazard reduction. [ABSTRACT FROM AUTHOR]

Large capacitor banks at medium-voltage levels are finding applications and greater acceptability in industrial distribution systems. However, these can give rise to current and voltage transients, stress the switching devices and insulation systems, and can be detrimental to the sensitive loads, i.e., drive systems. The paper discusses the methodology of the analysis and control of the switching transients. The results of the Electromagnetic Transients Program (EMTP) simulation are presented where applicable. [ABSTRACT FROM AUTHOR]

Small generators connected through a large impedance and operating in synchronism with a weak utility system are more likely to pull out of step on a large perturbation, i.e., a fault in the utility's system. Under an incident impact, which will be distributed unevenly among various machines, every machine will be retarded or accelerated, and undergo damped or divergent oscillations. This paper demonstrates that the small machines are more vulnerable and may fall out of step. This may plunge the entire process plant into a complete power outage on system separation. A case study of two small generating units and the improvements in the transient stability by fast system separation and load shedding is demonstrated. [ABSTRACT FROM AUTHOR]

New topologies for harmonic mitigation and active filters have come a long way, and these address the line-harmonic control at the source. These mitigate some of the disadvantages of passive filters, however, for nonliner loads above 1 MW the passive filters are an economical choice. This paper discusses two types of filters: band pass filters and damped filters, which are commonly applied. The operation of these filters is described with respect to the design and system limitations. The operating constraints are then superimposed. The development of this approach shows that there are design limitations and large system changes or modifications can result in higher distortion or even damage to filters in extreme cases. The constraints and limitations that a designer faces in implementing an effective filter design with modern tools of harmonic analysis, measurements, and system analysis are discussed. The paper shows that in most distribution systems it is practical and economical to implement passive filter designs, provided the required safeguards are considered. [ABSTRACT FROM AUTHOR]