IEEE Transactions on Industry Applications

Chapter 7 of a forthcoming book, Recommended Methods for Calculating AC Short-Circuit Currents in Industrial and Commercial Power Systems (IEEE Violet Book) is discussed. The book will be one of the IEEE Standards Board ``Color Book'' series of Recommended Practices prepared by the Industrial Power Systems Department of the IEEE Industry Applications Society. (It is being developed under IEEE Proj... View full abstract»

A low voltage equipment ground fault protection system for solidly grounded radial systems is described. The protection provides primary protection for source substation buses. It is capable of providing selective operation with downstream ground fault trip devices or phase-overcurrent devices set to detect ground faults. It also provides source transformer protection for phase-to-ground through f... View full abstract»

Recommendations are developed for selecting and connecting three single-phase transformers as a neutral-deriving transformer bank to ground a 480 V low-voltage power system supplied from a delta-connected source transformer. Assumptions made are that the system has no 277 V loads, and that the bank is used solely as a source of ground fault current. View full abstract»

Running overcurrent protection for motors rated 600 V or less is available in a variety of devices. Thermal overload relays, thermal protectors, magnetic and solid-state overload relays, multifunction solid-state motor protectors, and even short-circuit protective devices selected according to certain rules of the National Electrical Code (NEC) can provide varying degrees of protection. Selection ... View full abstract»

Increasing costs of unscheduled production downtime in manufacturing industries, coupled with high costs for repair of electrical distribution equipment, dictate that planned electrical maintenance and testing play an important role in the industrial manufacturing process. Subject matter important to performing a planned electrical maintenance and testing program of medium voltage industrial cable... View full abstract»

A new commutation circuit, especially suitable for pulsewidth-modulated (PWM) inverters, is described. The circuit does not require precharging of a commutation capacitor and is therefore ready for commutation at any time. This results in a very flexible and possibly programmable commutation control. Further-more, during PWM operation, the number of commutations per cycle can be halved when compar... View full abstract»

A description is given of a number of new circuit techniques, useful primarily in the control hardware of inverter drives using ``sub-harmonic''- or ``triangulation''-based pulsewidth modulation algorithms. Most aspects of such a system are covered. These include generation of the ``reference'' and ``carrier'' waveforms, carrier merging (including an asynchronous/synchronous carrier transition), o... View full abstract»

A variety of means have been used in the past for assessing the quality of pulsewidth modulated (PWM) inverter output voltages. A further analysis is given of the performance of such voltage sequences. The analysis is primarily computer-based, but experimental data are also included. In this case the discussion is clarified by the introduction of a new performance measure, based on the crest facto... View full abstract»

When a ``modified' McMurray inverter is used to drive 400-V cage induction machines from a nominal 560-V dc supply using pulsewidth modulation techniques, the voltage stresses the thyristor elements must withstand become severe. With a view to predicting these stresses accurately, the analysis of the inverter commutation interval-and the implementation in practice of commutation circuitry-is revie... View full abstract»

A rotating reference frame controller for ac machines which enables smooth four-quadrant drive operation with good torgue control bandwidth is described. The advantages which result from the control of stator magnetomotive force (MMF) in a rotor reference frame are illustrated with regard to synchronous and induction motors. The application of this method to a cycloconverter synchronous motor driv... View full abstract»

A dynamic model for simulation of the transient interaction between radially oriented permanent magnet-type synchronous machines and their corresponding transistorized current source power conditioners is presented. Some key machine parameters used in this dynamic model were obtained from finite element field solutions. This dynamic model was used to obtain the transient interaction between a 15-h... View full abstract»

The problem with lightning on distribution systems is defined. Lightning physics as it relates to distribution systems is discussed, and the background of line design based on direct strokes is explained. The historical evolution of lightning protection of distribution lines is covered with emphasis on present methods and designs. State of the art protective designs are explained and future method... View full abstract»

The application of metal-oxide surge arresters on underground systems, and their advantages at the riser pole and system-open points, is shown for arresters now available as well as those anticipated based on current technology. Improvements in protective margins are shown for each type of arrester discussed, with both livefront and deadfront applications addressed. View full abstract»

Rapidly evolving technology has made a broad variety of control system solutions available to industry. Most recently, microprocessors have formed the leading edge of the technology growth. The capability inherent in the present generation microprocessors will not only change the appearance of control plant-equipment, it will in fact change the methods for implementing wide control. The use of mic... View full abstract»

Reserve Mining Company's (Silver Bay,MN) distributed process control system is described. Primary emphasis is on how the system has evolved since the plant startup in July 1980, following completion of Reserve's on-land tailings disposal and quality improvement programs. Control concept changes and startup problems are discussed. Hindsight is utilized to determine areas of underdesign and overdesi... View full abstract»