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Textile, Fiber, and Film Industry Technical Conference, 1997., IEEE 1997 Annual

Date 6-8 May 1997

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  • 1997 IEEE Annual Textile, Fiber and Film Industry Technical Conference

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    Freely Available from IEEE
  • An intuitive analysis of harmonic power flow in electrical distribution systems

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    Many have already written much about power quality and harmonics in particular. As nonlinear loads such as lighting ballasts, electronics and variable-speed motor drives become a larger percentage of the total power consumed, the resulting harmonic currents can damage equipment. Furthermore, the local effects of harmonics are most pronounced with higher source impedance from the power source. Unless continually monitored, the power quality can degrade as the power system changes until the situation is symptomatic-a nuisance at first followed by more costly damage. The focus of this paper is an explanation for these well documented harmonics. Presented is a procedure for identifying the source of harmonic currents in the power distribution system as measured at various feeders and loads. Also presented are explanations by example that show why some harmonics exist while others do not. Harmonic cancellation is explained along with the presentation of a tool for understanding and predicting the results View full abstract»

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  • Installation considerations for IGBT AC drives

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    In the last four years, adjustable speed AC drive (ASD) manufacturers have migrated from bipolar junction transistor (BJT) semiconductors to insulated gate bipolar transistors (IGBTs) as the preferred output switching device. The advantage of IGBTs over BJTs is that device rise and fall time switching capability is 5-10 times faster, resulting in lower device switching loss and a more efficient drive. However, for a similar motor cable length as the BJT drive, the faster output voltage risetime of the IGBT drive may increase the dielectric voltage stress on the motor and cable due to a phenomenon called reflected wave. Faster output dv/dt transitions of IGBT drives also increases the possibility for phenomenon such as increased common mode (CM) electrical noise. Electromagnetic interference (EMI) problems and increased capacitive cable charging current problems. Also, experience suggests any pulse width modulated (PWM) drive with a steep fronted output voltage wave form may increase motor shaft voltage and lead to a bearing current phenomenon known as fluting. This paper provides a basic understanding of these issues, as well as solutions, to insure a successful drive system installation View full abstract»

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  • The impact of power system disturbances on AC-coil contactors

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    This paper is concerned with the impact of voltage sags on the performance of AC-coil contactors in industrial power systems. Sags have been commonly characterized in terms of magnitude and duration. However several experiments are presented which show that sag magnitude and duration are insufficient to characterize contactor performance. The results of these experiments show that contactor drop out and recovery depend on point on wave occurrence of the event as well as duration. The effect of the contactor shading rings on contactor transient performance is discussed View full abstract»

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  • Updating old process control systems to DCS, or moving out of the stone age!

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    Updating old/existing control systems to computer based, digital control systems (DCS) is a complex undertaking. It is anything but a “conversion” to computerized controls. More often than not, in fact, guaranteed 100% of the time, the existing process must be adequately “redefined”. Years of process updates, modifications and midnight fixes take their toll on documentation. The quantum change in man-machine interfaces (MMI) also requires considerable finesse in not just technical issues, but interpersonal and interdepartmental relationships. In addition, once the advantages and the capabilities of the new technology are appreciated, an explosion in new applications will confront the project engineer. Techniques to deal with these, and other, issues are described based on actual experience with four polyester resin, chemical process lines and associated infrastructure. Examples of what must be done differently, and why, are given along with their rationale View full abstract»

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  • High resistance grounding and fault finding on three phase three wire (delta) power systems

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    A debate has existed in the textile industry for years concerning the grounding of low voltage power systems. Since reliability and continuity of service are important in the textile industry, some engineers prefer using an ungrounded power system. Most of these systems now utilize a high resistance grounded source. Here, the author shows that the use of high resistance grounded, low voltage power systems makes good sense in the textile industry. Design, construction, operation and maintenance factors for such resistance grounded systems are also discussed View full abstract»

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  • Retail competition and Duke Power Company

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    Retail competition means that the customer will be able to choose their electricity supplier, sometime in the future. The author begins with a brief overview of the retail competition pilot that is going on in New Hampshire. After that, the author provides an overview of what's happening across the United States with retail competition. The author discusses his company's position and some of the key issues that need to be adequately addressed before retail competition begins View full abstract»

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  • Effects of voltage sags on AC motor drives

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    Voltage sags are normally described by magnitude variation and duration. In addition to these quantities, sags are also characterized by unbalance (asymmetry), nonsinusoidal waveshapes, and phase angle shift (phase jump). These factors are important for determining the behavior of AC motor drives during sags. Voltage unbalance and phase angle shifts cause large unbalanced source currents to excessive voltage ripple in the DC-link, and reduced DC-link average voltage. The response of the motor and drive to these varies considerably. Experimental results clearly show the load dependent behavior of a typical drive. The ability of the drive to ride-through a voltage sag is dependent upon the energy storage capacity of the DC-link capacitor, the speed and inertia of the load, the power consumed by the load, and the trip point settings of the drive. The control system of the drive has a great impact on the behavior of the drive during the sag and after recovery. The trip point settings of many drives can by field-adjusted and greatly improve many nuisance trips resulting from minor voltage sags View full abstract»

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  • Power quality: a utility and industry perspective

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    The widespread use of electronics in everything from equipment in the home to the control of huge and costly industrial processes has raised the awareness of power quality, issues and concerns over the last few years. The definition of power quality or more specifically, a power quality disturbance, is generally accepted as any change in the power (voltage, current, or frequency) that interferes with normal operation of electrical equipment. It is the susceptibility of the end-use equipment that defines the necessary level of power quality. The intent of this paper is to present information on power quality issues as they affect end-use equipment. The goal of industrial customers is, of course, to stay competitive in the production of their particular product or service. One effective way of accomplishing this is to reduce downtime and thus production loss by limiting the effects of power disturbances. The goal of electric utilities is to maintain a healthy and effective relationship with customers while also promoting the use of electrical energy. It is essential that industrial customers and the utility work together to provide solutions to power quality problems. This paper defines power disturbances in industry accepted terms, examine the sources and effects of these disturbances (for both the utility and the industry), and explore economical solutions based on the compatibility of the equipment and the electrical environment View full abstract»

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  • The air circuit breaker-50 years of technology

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    The low voltage air circuit breaker, the work horse of industrial electrical power systems, is now 50 years old. It has been changed and refined over its history. This paper reviews the development up to the air breaker as it is offered by today's manufacturers View full abstract»

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  • Communication systems to monitor and control the production environment

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    Advances in microprocessor technology made it possible to include intelligence in devices for better control and diagnostics. Using communication networks permits the connection of such devices on a bus system. Such communication systems have to fulfil multiple requirements depending on the application. The use of an open system communication bus and a programmable data structure fulfil the needs of drives and remote I/O controls. Consideration has to be given to the transmission speed for monitoring and application dependent control functions View full abstract»

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  • Economic justification of process improvement and automation projects

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    Economic justification is the burden of proof for the necessity of process improvement and automation projects. Process improvement and automation projects are undertaken to achieve business objectives. The prospective project's financial return versus the hurdle rate, and its various forms, is the primary information required to make business decisions. This paper describes the steps required to determine the financial return for a prospective project while taking into account life cycle costs View full abstract»

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