Richard L. Doughty

Testing update on protective clothing and equipment for electric arc exposure

Even though significant progress has been made in understanding and quantifying the hazards to personnel from electric arcs, additional testing is required to better estimate the incident energy produced by electric arcs on the many different types of electric power distribution systems. Additional arc testing has indicated that placing a three phase arc in a specific cubic box increased the incident energy by a factor of 3 compared to the same arc exposure in open air. Peak noise levels during the three-phase electric arc tests were found to be at levels sufficient to cause traumatic ear damage. Leather work gloves were found to provide protection for hands exceeding that of a Class 2 FR clothing system, but less than that of a Class 1 FR clothing system. Of all the head protective systems evaluated, hoods with 80 mil gold-coated polycarbonate windows were found to be the most protective.

The safety benefits of arc resistant metalclad medium voltage switchgear

One cause of serious injuries to electrical workers in the petrochemical industry is flash burns from arcing faults in medium voltage metalclad switchgear. First introduced in Europe, arc resistant switchgear designs are now being marketed in North America to eliminate this potential cause of injuries by containing the arc byproducts and venting the gases in a safe manner. This paper discusses current worker safety regulations, the arcing fault process, standards governing arc resistant switchgear, switchgear design, application and cost/benefit considerations. One manufacturers experience testing a new arc resistant switchgear design is included.<<ETX>>

Maintaining safe electrical work practices in a competitive environment

It is pointed out that worldwide competitive pressures have forced engineering and construction organizations to face increased workloads using fewer experienced personnel. Significant organizational and individual effort is required to maintain high standards of electrical safety in this climate. In addition, there is recent increased recognition of hazards from electrical high energy sources. The efforts of one corporation to maintain electrical safety performance are described. Basic electrical hazards are reviewed, and a flow-chart method of categorizing hazardous electrical tasks is presented. A matrix is provided to select appropriate personal protective equipment and identify procedural requirements.<<ETX>>The efforts of one corporation to maintain electrical safety performance are described. Basic electrical hazards are reviewed and a flow chart method of categorizing hazardous electrical tasks is presented. A matrix is provided to select appropriate personal protective equipment and identify procedural requirements.<<ETX>>

Introduction to IEEE 841-2001, IEEE standard for petroleum and chemical industry-severe duty totally enclosed fan-cooled (TEFC) squirrel-cage induction motors-up to and including 370 KW (500 HP)

IEEE 841-1994, IEEE Standard for petroleum and chemical industry severe duty totally enclosed fan-cooled (TEFC) squirrel-cage induction motors- up to and including 500 hp, issued in 1994, has been updated and improved. The scope includes three-phase severe duty TEFC squirrel-cage induction motors with antifriction bearings in sizes up to and including 370 kW (500 hp) and motor rated voltages of 200 V, 230 V, 460 V, 575 V, 2300 V and 4000 V at 60 Hertz. Changes to the standard are reviewed in detail. Requirements are identified that improve motor reliability and increase motor life.

The impact of efficiency on the economics of new motor purchase, motor repair, and motor replacement

As the cost of energy increases and energy resources become scarce, it is essential that the impact of efficiency be factored into economics decisions concerning new electric motor purchase, motor repair and motor replacement. Cash flow analysis techniques are applied to these decisions and simplified guidelines are presented to help users justify the purchase of premium efficiency motors.<<ETX>>

Safe application of totally enclosed motors in hazardous Class I, Division 2 locations

The authors discuss the role of motor internal, as well as external, surface temperature in determining if totally enclosed motors are safe for use in Class 1, Division 2 locations. The implications of using adjustable speed drives with TE motors are discussed. Recommendations are proposed for changes to the National Electrical Code (NEC), user application criteria, and additional nameplate information to be provided by the motor manufacturer.<<ETX>>

Electrical studies for an industrial gas turbine cogeneration facility

Electrical studies are required to assure the proper integration of a gas-turbine cogeneration facility into an existing industrial-plant electrical system and the connected utility grid. Details of such a study are presented, including boundary-limit definition for the system model, individual component modeling, load-flow and short-circuit studies, stability studies, and simulation of online isolation from the electric utility during system undervoltage or underfrequency conditions. The impact of such studies on the design process and plant system reliability is discussed. >

Motor terminal box explosions due to faults

Explosion of motor terminal boxes due to electrical faults in the terminal box or the motor is more frequent than generally recognised. Several case studies of actual terminal box explosions are presented, and potential safety hazards to personnel are identified. Industry standards governing motor terminal box construction are reviewed, and design alternatives to reduce potential hazards are explored.<<ETX>>

Cost effective motor surge capability

The use of surge capacitors to protect medium voltage induction motor windings from steep-fronted power surges has long been an accepted industry practice. Claims have been made that motor reliability would be improved without the use of surge capacitors if added interturn insulation were incorporated within the motor winding. This paper explores the surge-withstand ability of motors and the surge standards that have emerged. It presents a survey of industry practices and studies related to current motor applications, and provides the motor user with an economic evaluation to arrive at a cost-effective selection of motors with or without external surge protection.

Optimum electrical system design for a modern chlor-alkali plant

Development of the electrical distribution systems for a modern chlor-alkali plant is described starting from the conceptual design stage and continuing through final equipment design. Emphasis is placed on the electrical utility interface, main plant substation, 13.8 kV distribution system, rectifier design and control, and DC bus design. Load flow, voltage regulation, and harmonic studies are discussed.<<ETX>>