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In the United States, medium-voltage power distribution typically uses withdrawable circuit breaker switchgear. Withdrawable breakers allow for regular maintenance and provide an easily visible confirmation of circuit isolation but at a cost — having removable parts and the act of inserting and withdrawing breakers could result in the possibility of causing arc flash incidents. Modern fixed circuit...
In addition to controlling the voltage and current input signals, modern adjustable speed drives (ASD) or variable frequency drives (VFDs) also provide some motor protection functions. However, they fail to provide a biased thermal overload protection (BTP) that must reflect the motor heating due to overload, change in the ambient temperature, loss of cooling etc. A separate motor protection (SMP)...
AC induction motors operating on a variable frequency drive (VFD) have different operating characteristics from those operating on sine wave power and may benefit from specific design considerations. However, many applications will operate successfully using a readily available standard motor, which may offer the best overall value to the end-user. Today, many sine wave motor specifications include...
Traditionally, totally enclosed air-to-air cooled (TEAAC) motors have used tubular heat exchangers as means to dissipate internal heat. Today, many tubular heat exchangers used in TEAAC are optimized to achieve high heat transfer rates but are ultimately limited by the air flow configuration inside the motor that uses one part counter flow and one part parallel flow. This leads to poor heat exchanger...
More than ever Oil & Gas companies are looking for ways to increase their productivity and energy efficiency. To realize these goals electrification of the drive trains is essential. These solutions make use of variable speed drives to control speed and torque of the gas compressors and pumps which leads to a higher degree of process optimization. For loads with power requirements higher than...
An Oil and Gas Company's Arc Flash Electrical Safe Operations Program is a corporate initiative to prevent electrical arc flash injuries. The program implements the company general instruction — Electrical Arc Flash Hazard Mitigation, which provides minimum safe work requirements for protection of personnel in the workplace against electrical arc flash hazards in accordance with NFPA 70E. The program...
With literally hundreds of electric motor manufacturers from which to choose, sorting through options to find the best value can be a daunting task. This paper draws on the author's forty-plus years of experience to share practical methods for comparing motors before purchase. Interwoven into the paper are suggestions and techniques for improving designs of motors already in service. Areas of interest...
Partial discharge (PD) testing has long been an important tool for assessing the condition of the high voltage insulation in motor and generator stator windings. In the past several years, many motors have been powered from inverters which facilitate variable speed motor operation. The most common drive used today is the voltage-source, pulse width modulation (VS-PWM) type. VS-PWM drives rated up...
This paper will discuss the effects of implementing a specialized holistic lighting design, using high mast lights and the latest light fixture technology versus conventional lighting design methods throughout a new industrial petroleum processing facility. It is a case study that will examine the topics of engineering justification for the design decision, the final design outcomes, and the financial...
The Petroleum and Chemical industry continues to test the boundaries of project and system size to deliver bigger facilities, at less cost, and in a shorter timeframe. The effect is an increased pressure on systems, engineering capabilities, and disciplines that are dependent on others for information to deliver on a reduced schedule. This paper will present two key ideas for electrical system design...
There have been many discussions on the importance of balanced power supply for both best performance and for lower vibration during operation of industrial motors in petrochemical duty and related installations. Results of tests that were conducted on several low voltage IEEE 841 motors to observe the effect on vibration due to unbalanced power supply. Various increments of voltage imbalance from...
The current usage of the term “hybrid electric power”, when referring to electrical networks installed on offshore and marine assets refers to the coupling of energy transformation systems (ETS) that utilize different technologies to exchange energy with the electrical network. An ETS is composed of an energy transformation device (ETD) and if necessary an energy converter that is utilized to match...
This paper will discuss the many different ways to ground medium voltage generators. Single source as well as multiple source units, either unit connected or bus connected will be shown with preferred grounding schemes.
Typically, in offshore platforms, small reciprocating engine generators supply essential loads. At times, it may be necessary to energize a large transformer from these generators. Transformer energization draws high magnetizing current from the generators for several seconds and can have an adverse effect on the system voltage. This paper describes the voltage sag analysis of the energization of...
Current differential principle is a well-known principle used for protection of transformers, motors, generators, buses, and any other type of power equipment with input and output current measurements. Further the principle is used in developing percent differential protection which can be programmed to the desired sensitivity for detecting in-zone faults, and security during external faults. This...
Solid rotors can be adapted to synchronous motors of 5 MW and over in applications with high inertia loads. The eddy currents induced in the solid pole are used for starting of the motor and their paths are changed depending on the design of the rotor shape unlike the synchronous motors with damper windings or cages. In this paper, the starting characteristic of a 7 MW solid salient pole synchronous...
Many medium voltage power cables connecting substations, switchgear, and large pump motors in pipeline pumping stations are over 25 years old. The reliability of the station can be compromised by medium voltage cable failures. Factors identified that affect station reliability include cable age, original cable installation practices, craft work, weather exposure, length, and increasing electrical...
The IECEx Conformity Assessment (CA) System is operated under the direction of the International Electrotechnical Commission (IEC). It comprises four separate schemes that provide international services to industries involved with explosive atmospheres (Ex) applications. These services include the certification of Ex equipment, the certification of Ex service facilities, and the certification of Ex...
When generators or motors are started via variable frequency drive (VFD), the initial frequency is very low, on the order of few hertz, and can be low for a considerable amount of time or even permanently. It is not well recognized in the industry about consequences of the low frequency for the currents transformers (CTs) performance and how this affects the protection performance as well. First of...
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