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Most people understand that electricity is essential to our everyday life, both at home and on the job. Perhaps because it has become such a familiar part of our daily life that many of us don't give much thought to how much our work and other activities depend on a reliable source of electricity. More importantly, we tend to overlook, ignore, or just don't understand the hazards electricity poses...
This paper was written to share the experience acquired in the specification of surge suppressors (snubbers) for protection against switching transients' overvoltage resulting primarily in dry-type transformers failures in some plants in Brazil and North America. This paper will also explain about the snubber ratings (damping resistor, surge capacitor and surge arrester), the assembly special cares,...
Many pulp and paper operations use hardware-based Continuous Emissions Monitoring systems (CEMS) to track boiler emissions. This hardware approach uses pumps, filters and analyzing instruments to draw emissions from the combustion equipment and measure their levels. Using hardware can be costly and time consuming as it requires daily deployments of calibration gases to confirm the system is providing...
Continuity of electrical power supply to continuous processes is vital to overall success in an industrial setting. It is therefore critically important to evaluate accurately the degree to which transformer insulation has been exposed to high temperatures and the degree of service aging which has occurred, even at normal temperatures. Concentration of carbon oxides dissolved in the oil is one marker...
The arc flash task tables were introduced in the 2000 edition of NFPA 70E(1). They have remained basically unchanged since then. The 2015 edition of NFPA 70E(2) presents arc flash task tables that follow a “clean sheet” approach and do not resemble the previous edition's tables at all. This paper covers the new Table Method in detail, as well as some of the thought process behind it.
Electrical System Preventive and Predictive Maintenance methodologies have experienced growth due to new available technologies. This paper will review the historical and current approaches to electrical equipment maintenance, and also provide available technologies which support the future modes of equipment maintenance. Low Voltage and Medium Voltage systems will be reviewed. The need for improved...
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. The paper describes 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;...
Stator current signature analysis on induction motors is a proven method for diagnosing rotor squirrel cage winding defects and air gap eccentricity problems. With this technology, specific frequency current components can be identified as an indication of cage winding defects as well as a non-uniform gap between the stator and rotor. Because this data is generally collected periodically, it is important...
Given today's slow economic growth, reduced plant engineering and maintenance staffing and tight capital budget constraints, understanding how best to propose, plan, execute and allocate limited resources for successful process control system migrations is imperative for manufacturers seeking to maintain or increase productivity and efficiencies. Unfortunately, there is little published data on best...
Modern day manufacturing practices are focusing on maximizing production while actively pursuing ways to mitigate potential failures in their products. With rotating machinery, part of this pursuit requires qualification checkpoints during manufacturing processes. For motor stators, it is essential to perform in-process insulation testing to ensure the dielectric integrity of the system is maintained...
This paper describes power and efficiency measurement in motor and variable frequency drive systems. The paper first presents an overview of existing international standards relating to motor and variable frequency drives systems and then discusses some of the challenges involved in measuring the power from the pulse-width modulated source. Differences in power measurements due to different power...
Building company-wide safety programs to overcome the challenges of multiple plants, multiple regions, differing standards and differing technologies in the forest products industry.
It is better than 20-years since the newer cable field-testing methods of Very Low Frequency (VLF), Tan Delta, and field partial discharge testing have been introduced to the field-testing arena. Over time these technologies have matured, spawned a new testing industry, IEEE standards, technical committees, and a plethora of technical papers. How has this affected the cable manufacturer and what is...
The U.S. Department of Energy issued new efficiency regulations in May of 2014 for integral horsepower motors effective June 2016. This paper will provide an update on these new regulations for 1 through 500 HP low voltage AC induction motors. The scope of coverage has been expanded to cover more configurations that in previous regulations. Also 56 frame enclosed motors are covered.
For Forest Products based industries, the significant benefits of pre-emptive arc-flash protection and online condition monitoring of electrical equipment are not well known. This paper provides a summary the research surrounding the development and testing of new advanced sensor technologies for this purpose. More extensive and detailed measurements, regarding significant defects leading to an arc...
Motor current signature analysis (MCSA) has become an essential part of the preventive maintenance program for monitoring the condition of the rotor cage in medium voltage induction motors in the pulp and paper industry. However, many cases of false indications due to interference from the motor or load have been reported. False indications can result in unnecessary inspection and outage costs (false...
The application of differential protection has been shown to be effective in many applications within the Forest Product based industries. However, there are some aspects of differential protection which need special consideration. Some differential configurations may be harmful to the systems to which they were installed to protect. This paper will cover a few of the basics surrounding typical differential...
In pulp and paper plants, power transformers play a critical role in process continuity. These transformers are subject to internal short circuits, external short circuits and abnormal operating conditions. The following protection challenges to power transformers will be explored, and methods to improve the protection provided: • Remanence in a current transformer (CT) may cause misoperation of phase...
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