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The IEC-based term “Equipment Protection Levels (EPLs)“ refers to a disciplined process for identifying and selecting equipment for installation in hazardous (classified) locations. This disciplined process involves special equipment markings, an optional comprehensive risk assessment after area classification, and a selection criteria to identify the equipment that can be installed in hazardous (classified)...
Gas turbines often provide the power necessary for the process at production sites. These power systems are much different than the utility grid. Being smaller they are subject to large disturbances causing wide variations in turbine power over short periods of time. These power swings can have negative effects on some types of turbines designed to have low emission of nitrogen oxides. Such turbines...
When properly employed, oil mist lubrication offers many benefits to the operation of electric motors with rolling element bearings. Cooler operating temperatures, increased reliability, and decreased maintenance issues are some of the achievable advantages associated with this system. However, there are also a host of concerns associated with its use. The costs of installing and operating a mist...
The U.S. Department of Energy (DOE) must review efficiency standards every five years and make recommendations on changes. This paper will provide an update on current rules under study for 1 through 500 HP AC induction motors. The DOE is evaluating raising motor efficiency above premium levels by one to three NEMA efficiency bands. The motor industry feels that a better solution is to standardize...
The grounding of electrical systems has become commonplace with little or no thought given to the consequences of indiscriminate grounding. The study of the history of application of electricity with respect to grounding reveals that early procedures that solved the problem at hand resulted in dangerous and hazardous electrical conditions years later. Lessons that Edison learned and have been forgotten...
Modern motor protection relays are capable of long term failure monitoring and diagnostics based on information collected by a powerful data acquisition system. This includes predicting life time of motors. This paper presents an advanced algorithm capable of performing such tasks. It is applicable to different types of rotating electric machines depending on their design. The components are: stator...
Electrical equipment used in cold weather regions are subjected to different environmental conditions than most standard approvals cover. There are two main areas of concern for products used in cold weather — safety and function. For Class I classified locations the ability of the equipment to maintain its explosion protection properties at low temperatures is of major importance. Low temperatures...
Almost 56% of the total primary energy used (about 100 Quads in 2010) in USA is wasted. 40% of the total energy is used to generate electricity with an overall efficiency of about 32% (or 1/3rd). The transportation sector uses about 27% (1/4th) with an overall efficiency of 25%. The industrial/ commercial sector uses 47% with an overall efficiency of 55%. Energy Efficiency has been a topic of great...
Many low-voltage (LV) adjustable speed drives (ASD's) have a built-in ground-fault function that is not capable of detecting a low-level ground fault and may require the use of a suitable supplemental protection relay for reliable detection. While high resistance grounding (HRG) has become the norm, over recent decades, in many industrial facilities the surge in application of ASD's has challenged...
As part of a factory acceptance test program for high voltage motors, end users sometimes specify a black-out test. This is a traditional offline inspection where the stator is placed in complete darkness, each phase is energized to 115% of rated line-to-neutral voltage, and both ends of the stator are observed to determine the presence, location and severity of endwinding surface partial discharges...
The incremental efficiency improvements achieved with induction motors have been mostly accomplished by adding material to the designs of the prior efficiency level. In order to achieve levels beyond NEMA Premium (or beyond lE3), it has been recognized that a different technology must be employed. The working groups for IEC efficiency levels have stated that inverter-fed permanent-magnet motors are...
The manufacturer assessment during the design stage inception for potential resonances near any predicted operating force as well as the overall system amplitude response is essential to ensure the proper field operation. Using a model that takes into account the magnetic and mechanical loads it is possible to optimize the design and improve reliability, minimize resonances and reduce vibration amplitudes...
National Electrical Manufacturers Association (NEMA) Type 7 explosion-proof enclosures are widely regarded for their robust construction and dependable operation. These enclosures are sustained without the additional safety systems required to ensure operation of a purged and pressurized piece of equipment. Similarly, NEMA Type 7 enclosures are maintained without the costly component inventory which...
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...
Directly coupled converter-fed electric motors for oil & gas applications, especially for pipeline and process compressors, have become more common in recent years due to increased efficiency and precise process control. The pipeline industry is demanding more Megawatts at higher speeds, which means large high-speed electric motors are used in applications directly coupled to high-speed centrifugal...
As a result of major revamp and several expansion projects to a 30-year old world-class petrochemical refinery, the total refinery power demand increased from 67MVA to 100MVA with a corresponding lagging power factor decrease from 93% to 89% at the 34.5kV system. The refinery has a secondary selective system and gets its power from utility company via two main power transformers. Each transformer...
Electrical infrastructure equipment in the petrochemical and/or oil and gas industry in North America is generally 40 or more years old. The life and reliability of electrical equipment in this age range can be compromised due to operating conditions such as exposure to moisture and chemicals, loading, temperature, vibration, and mechanical stress over the life of the equipment. Electrical equipment...
Within the engineering industry it is a known fact that there are a multitude of cases where the individual components test satisfactorily however when the parts are combined, the net sum performance is not as good as the individual parts. Static and dynamic compatibility of the individual drive system component should be matched together in order to achieve a satisfactory system performance. This...
Engineering, in its variety of disciplines, has always been to overcome challenges. The present overriding challenge is to maximize energy efficiency and reduce energy usage. A significant stage in accomplishing this challenge is the emphasis on the installation of premium efficient motors compliant with National Electrical Manufacturers Association (NEMA) Standard MG1-2011 table 12-12 Premium Efficiency...
Over the years, there has been a significant evolution in power semiconductor devices from small, low power devices to very high capacity semiconductor devices. As a result, multi-megawatt range adjustable speed drive systems are gaining acceptance in the global onshore and offshore oil and gas industry. Adjustable speed drives are used on liquefied natural gas compressor trains, gas pipeline compressors...
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