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This paper presents a novel digital technique for bus-bars protection. The technique is based on deriving a directional quantity proportional to the postfault current signal and the prefault voltage signal. The prefault current signal is also used to compensate the current signal during the current transformer (CT) saturation. The performance of the technique was investigated for a variety of operating conditions, for CT saturation, high fault resistance, source impedance, and for several bus-bar configurations. Results show that the technique is stable during early and severe CT saturations and it is able to offer very high accuracy and speed in fault detection.

This paper examines improvement of power system dynamics by use of unified power flow controllers, thyristor controlled phase shifting transformers and thyristor controlled series capacitors. Models suitable for incorporation in dynamic simulation programs for studying angle stability are analysed. A control strategy for the damping of electromechanical power oscillations using an energy function method is derived. The achieved control laws are shown to be effective both for the damping of large signal and small signal disturbances and are robust with respect to loading condition, fault location and network structure. Furthermore, the control inputs are easily attainable from locally measurable variables. The effectiveness of the controls are demonstrated for model power systems.

A reduced wall 138kV HPOF pipe-type cable having a 700 kcmil (355 mm2) compact round copper conductor and 348 mils (8.8 mm) of insulation and two types of joints have been developed for re-conductoring existing 69kV HPOF feeders utilizing 5 inch (127 mm) outside diameter pipes on the Florida Power & Light Company (FP& L) system. Laboratory test results on the cable and two joints, one employing hard paper and the other high density crepe paper tapes, are reported. The commercial cable installation is described. Test results are also given on an improved design reduced wall 138kV HPOF pipe-type cable having a 2000 kcmil (1015 mm2) compact segmental copper conductor and 379 mils (9.6 mm) of insulation and a high density crepe paper joint intended for re-conductoring a 69kV HPOF pipe-type feeder using the existing 6-5/8 inch (168 mm) outside diameter pipes. The cable and joint satisfactorily passed all requirements of AEIC CS2-82 (4th Edition) [4].

With a view to making a precise analysis on operation of protective relays in power systems for noise, a new noise testing equipment has been developed and installed for trial, which is capable of generating a wide band of noise with frequencies ranging from 1 kHz to 2 MHz and also of controlling conditions under which the noise is applied. A series of noise withstand capability tests were conducted with the aid of this testing equipment for some existing static relays. This paper deals with firstly the specifications and some features of the testing equipment and, secondly some findings on the noise withstand capability of protective relays through the test results.

This paper describes the computerized analysis which was conducted to ensure personnel safety and pipeline integrity during power system faults occuring near the Trans Quebec & Maritimes gas pipeline. The pipeline section considered was constructed in the vicinity of two Hydro-Quebec power substations and a number of high voltage transmission line structures. The effects of electromagnetic induction and through-earth conduction caused by currents originating from Hydro-Quebec facilities during ground fault conditions are examined and their impact on the gas pipeline are quantified.

A high-pressure gas-filled (HPGF) pipe-type cable system rated 69kV has been developed for operation at Prudhoe Bay, Alaska, which is at the North Slope above the Arctic Circle. A minimum ground ambient of -10°C is applicable to the major portion of the circuit which is buried. The cables installed in pipes across a 46 m (150 foot) long bridge, the terminal riser cables and the cable terminals experience a minimum air ambient of -48°C. The cable design for each of these ambient temperatures required special consideration with regard to the insulation structure and impregnant to be employed for the paper insulation. This paper describes the investigation of materials, cable models and prototype cables to achieve the physical and electrical properties required for the application. For the buried cable, a polybutene impregnant having a viscosity lower than normally employed for HPGF cable was used. For the cables exposed to the lower ambient air temperature, a phenylmethyl polysiloxane silicone fluid was selected as the impregnant. A transition joint between the polybutene and silicone impregnated cables was developed. Standard gas-filled terminals were modified for service at the low ambient air temperature. The successful completion of this R&D project has provided a rugged, reliable high voltage cable system suitable for transmitting power in an arctic environment.

An in - death analysis of fundamental Parameters Pertaining to Ultra-High-Speed Relay (UHSR) settings is carried out. The performance of the Independent Directional Detector (DD1) unit is analyzed in terms of the setting application values of current and voltage for a variety of faults and systems conditions. Relative underreach curves are presentes to show the influence of fault type and resistance on the unit detection range for a given setting. The paper describes a setting approach, based on the above analysis, as actually implemented in a 500 KV double circuit line, with a fuller utilization of the independent mode.

The development of the gapless metal oxide (ZnO) surge arrester has presented the arrester engineer with new materials and an opportunity for new designs. This situation arises because the gapless surge arrester is electrically active throughout its lifetime whereas its predecessor, the silicon carbide arrester, was electrically passive being electrically isolated with gap structures. The prime consideration is one of reliably estimating the lifetime of a gapless ZnO surge arrester under continuous ac stress while maintaining the capability not only to limit surge voltages but also to absorb energy inputs resulting from lightning or switching surges and temporary overvoltages. In this paper we establish a procedure for reliably estimating the lifetime of gapless metal oxide surge arresters for ac application by incorporating the device characteristics into design requirements. This method is illustrated for metal oxide surge arrester elements that exhibit a predictable linear resistive current versus time1/2 behavior as a function of applied voltage and temperature.

Processing of the fault transients for eliminating the unwanted signals, is essential. for the EHV system protection. The various components which perform this function, and the filters in particular, introduce a significant delay in the operation of the protective devices. The paper investigates the various sources of time delay, and presents a digital. time delay compensation scheme, together with some test results.

This paper proposes a new algorithm for an emergency control system which prevents transient instability by generator tripping. The algorithm is based on the energy function method, and it precisely can determine the amount of generation to be tripped. A prototype of the proposed system has been made, and it has been confirmed that the algorithm has been easily implemented in a micro-computer. Furthermore, test results show that the algorithm works well in an ATL (Artificial Transmission Line) System. This paper describes theoretical aspects of the algorithm, implementation and test results.

This paper describes the design and testing of a digital ultra high speed (UHS) travelling wave based protective relay. It shows how a prototype has been realized by a simple and fairly low cost (a few hundred dollars for parts) dedicated multi-microprocessor system. The paper presents also the results of the tests carried out on the prototype by using a microprocessor based complex waveform signal generator (CWSG) which displays the output of a mainframe computer-based electromagnetic transients program (EMTP) in real time. The relay showed good practical behaviour, especially with regard to the UHS feature and faulted phase selection and fault classification capability.

This paper summarizes a study of ground potential distribution during faults to the ground in the neighborhood of Itaipu Power Plant taking into account the influence of the different resistivities of river, river banks, dam and reservoir. This study enables the dimensioning of the cable facilities leaving the power plant. Selection of the critical configuration and fault location are discussed. Ground potential distribution is computed by Kimbark's "current ray technique". This method lends itself to the modeling complex horizontal and vertical variations of soil resistivities.

On an actual 550kV GIS (gas-insulated switchgear), the restriking surges of disconnecting switches at a high frequency of several MHz were successfully measured by employing two different methods. Further, by comparing the measured waveforms with waveforms obtained through calculations, it has been proved that restriking surge of disconnecting switches can be estimated by conducting calculations with considerably high accuracy. Also included, in this paper are certain suggestions regarding GIS simulation methods to be adopted for the calculations, while concurrently reported are the results of calculations on 111 circuit configurations at 10 different GIS's.

This paper describes the recently developed microprocessor-based stabilizing control equipment for survival of isolated mid-city power system having heavy load and large shunt capacitance (Underground cables) of TOKYO ELECTRIC POWER COMPANY (TEPCO). The active power balance and voltage stabilizing control scheme is realized by high-speed control of the 66KV load feeders, shunt reactors, shunt capacitors and 275KV & 154KV underground transmission cables dispersed in the power system.

Design of strength of station structures and clearances to accommodate forces and motions of strain bus during short circuit faults has been based on an energy method and a pendulum swing out model at Ontario Hydro. The energy method was developed some time ago to calculate the forces in a strain bus at the moment of zero motion following a fault. Several recent extensions of this approach are described in this paper. These include: (i) In-depth comparisons of predictions of peak tension, time of peak tension, and force on the structure with values from experiments on simple bus arrangements. (ii) Studies of insulator static and dynamic properties and incorporation of these values in the program. (iii) Extension of the theory to asymmetric faults and to four conductor busses. This method of calculation has recently been used in the probabilistic analysis of the uprating of Ontario Hydro's Middleport Transformer Station (TS) as well as a number of other design applications. This study demonstrates the overall accuracy of this relatively simple approach and its potential for application to more complex arrangements of strain bus. This paper and three companion papers present the probabilistic uprating process as applied to Middleport TS.

A computer oriented method to calculate the total accident probability of the HVDC grounding system is developed in this paper in order to evaluate the safety level of it. The method is derived step by step, from the basic statistical parameters, based on the peculiarity of the dc grounding electrode. A detailed computational procedure is illustrated by block diagram. The application of the proposed method is explicated in this paper with a simple numerical example.

Increasing levels of fault currents in the Ontario Hydro system have made the designs of some existing 230 kV strain bus station installations inadequate if conventional deterministic design techniques are employed. Uprating costs could be reduced by several million dollars per station, if a greater short-circuit capability for the existing strain bus and structures could be established using new probabilistic techniques. For this purpose, a multi-discipline task force from a variety of divisions within Ontario Hydro was created to evaluate 230 kV insulator string failure probabilities at Middleport Transformer Station (TS) and assess the impact of possible failures in terms of personnel safety, repair costs, outage costs, and system reliability. This paper and the three companion papers present an overview of the probabilistic uprating process as applied at Middleport TS. The study indicated that only marginal work (if any) is required to maintain adequate safety, reliability and cost criteria, assuming that currents are limited to within the existing 230 kV circuit breaker ratings.

This paper reviews the current status of distribution system reliability evaluation in Canadian utilities as determined by a study conducted for the Canadian Electrical Association [1]. The information was obtained by surveying the Canadian utility industry. Some of the results relating to the indices utilized and the use made of data collected by the responding utilities are conpared with current practice in the United States.

A method and a computer program for interpreting soil measurement data are presented. The method employs a statistical estimation of soil parameters from four pin or three pin measurements. The analysis provides (1) the best estimate of soil parameters, (2) the error of the parameters versus confidence level, (3) a pictorial view of how well the estimated soil model fits the measurements, and (4) the measurements which are not consistent (bad measurements). The methodology is applicable to data obtained with four or three pin method over a small or a large area. It performs best when applied to measurements taken at various locations of the area of interest. A computer program has been developed based on this methodology with the symbolic name SOMIP (SOil Measurements Interpretation Program). Implementation details are discussed in this paper. The performance of the methodology is compared with test model data. In addition, the experience gained in interpreting soil resistivity measurement with the program SOMIP is presented in this paper. Specifically, many sets of actual data, taken from four major utilities, has been analyzed and the results are presented and discussed.

This paper gives an analytical explanation of a voltage jump phenomenon noticed at the transformer terminal. In particular, it is proven that as a consequence of certain non-synchronous switching conditions, the voltage of the last disconnected transformer terminal will suddenly increase. Overvoltages as a consequence of non-synchronous switching are calculated and compared with measured voltage waveforms.

This paper provides background Information for analyzing step and touch potentials near transmission structures. A companion paper provides engineering evaluation for analyzing these potentials.

This paper provides engineering evaluation for analyzing step and touch potentials near transmission structures. A simplified approach useful for "ball park" estimates is shown along with the explanation of a rigorous approach necessary for a more thorough evaluation. A companion paper provides background information on many of the factors involved.

This paper deals with laboratory tests in order to qualify a new type of sheath voltage limiter (SVL) based on Zinc oxide non linear resistor (ZnO). The aim of the tests was to determine the maximum performance of the SVL and to investigate the possibility of ageing phenomena. The research was based on several years of field experience gained on silicon carbide (SiC) SVL. The high performance and the better reliability of the ZnO SVL, compared with the traditional SiC one, allow greater freedom in the project design of cable installations, making possible an increase in cable length and in the permissible short circuit current. The new SVL is now being installed to protect special bonding connections of high power cables.

Large phase-shifting transformers (PST's) are not common in the United States, consequently, little has been published concerning these unique transformers. This paper will discuss the application, design, testing, and protection of two parallel 1000 MVA 230kV PST's which were installed at the Plant Daniel substation of Mississippi Power Company (MPC) on the McKnight 50OkV interconnection with Gulf States Utilities (GSU). These units have been in operation since May, 1984 and have experienced no problems.

The paper enlightens the parallel development of the characteristic of the arresters and of the procedure to test their capability to discharge the energy during operation consequent to switching overvoltages, test called "long duration current impulse withstand (LDCIW) test". It is shown that the procedure for the LDCIW test prescribed in the current edition of IEC Publication 99-1 (1970) is strictly related to the peculiar features of active-gap arresters, and that is not necessary to adopt it also in the Draft of Standards for metal-oxide arresters (MOA) under preparation by IEC TC 37 "Surge Arresters". The main drawback of this procedure is that it requires a large number of different test circuits if a laboratory intends to be equipped for testing arrester sections of all classes and all rated voltages. An alternative test procedure for LDCIW tests on MOAs is described and analyzed, which is equivalent to that proposed in the mentioned Draft. It practically requires only one test circuit, and implies smaller tolerances on the energy stress on the arrester, so making the test more reproducible. It is finally shown that the alternative test procedure can be improved to test arresters against any kind of switching overvoltages, and not only to line discharge, as the current procedure.

Many approaches can be taken when evaluating the replacement of PCB-filled capacitors on overhead distribtion feeders. The Pennsylvania Power and Light Company (PP&L) utilized the opportunity to re-evaluate capacitor application techniques as well as capacitor placement. This paper summarizes a joint PP&L/Westinghouse effort to determine the value of a complete capacitor-engineering evaluation as compared with a strict one-for-one unit replacement. Examination of seven feeders yielded significant reduction in real line losses, formulating the justification for future capacitor application efforts.

This paper describes the suppression of the transient overvoltage caused by gas disconnector switching of a small capacitive charging current in a gas insulated switchgear substation. The overvoltage is suppressed by the insertion of a resistor with an appropriate value during the switching. A scale model gas disconnector with the resistor is developed. The overvoltage suppression effect and the charging current breaking capability of the gas disconnector are experimentally confirmed. A prototype ultra high voltage gas disconnector is trial manufactured and tested.

About ten years ago, an axial magnetic field electrode was developed for vacuum circuit breakers. Since then, through various improvements in its structure, this electrode has been refined for practical application in vacuum circuit breaker interrupters. The application has successfully covered not only medium-voltage circuit breakers, but also high-voltage (84kV), dc current and large-current circuit breakers. In this paper, our ten years' experience in this area are described.

This paper presents the most significant results of a comprehensive Transient Network Analyzer study evaluating approximately 2500 MVAr of 345 kV switched capacitor banks throughout central eastern and southeastern New York. The study evaluated various concerns associated with switched shunt capacitor applications. These concerns include transient overvoltages at the switched capacitor and other locations during normal and abnormal capacitor bank switchings. The paper evaluates surge arrester duties, switching device requirements, current limiting reactors, and design requirements to avoid possible severe overvoltages.

Planning of an HVDC transmission system embedded into an existing ac network may require unique control and converter equipment capability in order to satisfy stability requirements of the network. The planning and design of the Intermountain Power Project HVDC transmission system are based on unique control performance features for power transfers during terminal ac faults, rapid power recovery following fault clearing and utilization of exceptionally high transient overload capability of 2 per unit during the post-fault period to maintain system stability. The Department, in its efforts to meet the Western Systems Coordinating Council's (WSCC) reliability criteria, developed and incorporated into its HVDC specifications very rigorous reliability and availability requirements. One objective of this project was to attain the unusually low bipolar converter system outage frequency goal of one outage in five years to achieve a bipole performance rating equivalent to two ac circuits of similar capability. The reliability goals of this project have provided one of the impetus for revisions to the WSCC Reliability Criteria for System Design. The reliability goals and other features adopted for the Intermountain HVDC transmission system are discussed in this paper and study results are included to demonstrate the effectiveness of various controls implemented as stability enhancement techniques.

The paper presents a mathematical corona model and its use for transmission line modelling with corona and, if desired, with frequency dependence of its parameters. The corona model has been developed from macroscopical physical laws, reflecting relations between charge, electric field intensity and voltage. Space charges, their development and their displacement are taken into account. The parameters of the model are determined so that the simulated qv curves closely fit those available from measurements. The corona model is then used as an element of the discretized transmission line model. This consists either of longitudinal inductances or of travel delay modules. Modelling of frequency dependence is optional. The line equations are integrated using the trapezoidal rule, so that Norton equivalents are obtained for the two line ends for the purpose of interfacing with the external system. Thus the model is fully compatible with an Electro-Magnetic Transients Program (EMTP).

Developing the constants for small induction generator and synchronous generator application studies in Distribution System Generation (DSG) applications can quickly exceed time and budget constraints. The development of reliable constants for induction machines can be aided by suggested full-load calculations. If acquired data seem inconsistent, a method to adjust the constants using a small computer is discussed. Finally, constants for eleven example machines are presented. Synchronous generator constants may also be difficult to acquire especially if subtransient detail is needed. Excitation and governor control system data is rarely available when required. The paper discusses procedures to check the data and presents four examples.

The purpose of this paper is to evaluate the effectiveness of the capacitive series compensation of long lines from both the technical and economical points of view. It will be shown that the achieved increase in the transmission line capacity using this technique will be economically justified only for certain ranges of line length, line voltage and other design parameters. A procedure is also presented to find the optimal degree of series compensation and the location of the compensating condensers. The objective function for the optimization is considered to be the equivalent cost of the increase in the line maximum power limit minus the cost of the compensating condensers. Information is also given about the effect of different electrical and economical design parameters on the optimal compensation conditions.

This paper presents a statistical method to calculate the minimum safety distance for live-line maintenance. The method takes into account the complexity of the tower gap configuration and the presence of the lineman working at the line potential. It includes the inherent dispersion of the dielectric characteristics of the air gaps such as the probability of flashover and the times-to-flashover. Laboratory tests were also performed to corroborate the results of the study, checking not only the performance of the various live-line tools but also the effectiveness of the by-passing insulators protective device and the occurrence of broken insulators in the string.

A computer-based distribution SCADA (Supervisory Control and Data Acquisition) system and a geographical display system of distribution network diagrams have been developed by Tokyo Electric Power Company (TEPCO) and Toshiba Corporation. In this paper, development objects, system configuration, system functions and feeder switching algorithm of the distribution SCADA system, and system configuration, software and database of the geographical display system are described.

A new travelling wave digital protection scheme to be used as an ultra high speed (UHS) EHV/ UHV transmission line relay is presented in this paper. Some of the potential problems and limitations associated with other travelling wave schemes are avoided. Verification of the relay operating principles is presented through digital computer numerical simulation using an electromagnetic transients program (EMTP) in conjunction with simulation of the proposed algorithm. Parallel digital processing is incorporated through multi-microprocessor implementation. Hardware and software of a multiprocessor prototype are managed in a way to fit the algorithm requirements in as simple a construction as possible. The resulting scheme achieves significantly improved security and dependability, in addition to the main features: fault classification and UHS phase selection in selective-pole schemes with minimum communication between the protected ends.

The high frequency components in fault waveforms present undesirable effects to most fault location algorithms and as a consequence filtering of postfault signals, to remove the high frequency transients, is essential for accurate fault location. A fault location algorithm that derives from travelling wave principles can cope with high frequency transients since these basically depend on travelling wave phenomena. The development of such an algorithm is the objective of this paper. Using the telegraph equations as a line model, voltage and current samples taken at one end of a line within the first 5 ms of fault inception are used to generate instantaneous voltage and current profiles for the rest of the transmission line. The voltage and current estimation is based on the solution of the equations of the line model by the method of characteristics. Criteria functions involving any of the square of the voltage, the square of the current, or the product of the two are applied for determination of the fault position. Fault position is given by the peak variation in tangent to the above basic functions. The algorithm finds application in fault location on two and three-terminal networks at both transmission and distribution levels.

A basic approach for quantitative evaluation of "Stochastically Periodic" harmonics effects on electrical equipment is presented. The main contribution of this paper is in defining and explaining a mathematical method which enables the estimation of the additional losses and the loss of life caused by stochastically periodic current/voltage harmonics. A practical case of N identical converters, randomly operated, is analyzed. The suggested method is applied to determine admissible levels of randomly periodic voltage harmonics for power capacitors.

The combined use of dc and ac transmissions or so-called hybrid transmission was under study, employing both dc and ac systems to enable stable transmission of 10,000 MW of electric power generated by the BWR nuclear plant, scheduled to be built about 800 km away from the center of load. It was thus necessary to develop a hybrid power transmission control system, the hybrid power transmission system consisting of a high voltage dc transmission system (HVDC) and an ultrahigh voltage ac transmission system (UHVAC). It was also necessary to develop a control system for HVDC transmission which protects the BWR nuclear power plant from being influenced by any change in transmission mode that occurs as a result of faults on the UHVAC side when the entire power of the BWR plant is being sent by the HVDC transmission. This paper clarifies the requirements for the HVDC system control during hybrid transmission and also during dc transmission. The control method that satisfies these requirements was studied to develop a control algorithm. The adequacy of the HVDC control for hybrid transmission and for dc transmission was examined by digital simulation. Based on this analysis a BWR simulator, coordinated control equipment and HVDC control equipment were developed to conduct a dynamic characteristic test using a power system model. It was verified that ordinary control and transient control during hybrid transmission and dc transmission have the desired control characteristics.

Equivalent networks can be used in power system simulation to reduce simulation equipment or computer time and memory space. In this paper, an iterative method is developed for synthesizing one-port equivalent networks by the removal of poles corresponding to resonances of the driving-point impedance or admittance function. This results in networks formed by the series or parallel connection of modular RLC circuits. The RLC values are calculated using a parameter-optimization technique. Multi-port equivalent networks are first configured as ? or T forme composed of one-port network branches and the latters are then synthesized by the proposed method for one-port equivalent networks.

Transformers and reactors used in the electric power transmission systems show non-linear magnetization characteristics, the exact knowledge of which is essential to the study of system transient operation. This paper describes a measurement method for these characteristics, based on D.C. EXCITATION. During such excitation, only applied voltage and absorbed current are measured and recorded, to be afterwards numerically processed. This measurement requires only a very small power, usually lower than 0.01 p.u. of the tested unit rated power; it is very accurate and makes it possible to obtain magnetization characteristics up to currents higher than the rated current. Theoretical bases on which the measurements are grounded, practical considerations on their performing and a set or relevant results on power high voltage transformers and reactors are afterwards exposed. More, it is possible by a d.c. excitation to measure magnetization characteristics which cannot be otherwise determined.

The use of vacuum circult breakers In motor feeder applications (where motor terminal surge protection is not normally used) may require overvoltage surge protection within the switchgear to properly protect the motors. This need can be fulfilled by surge limiters designed for installation within the switchgear connected to the load side of the vacuum circuit breaker. This paper reviews the basic phenomena which cause vacuum switchgear related surges and dtscusses the need for surge limiters. This paper also describes the design of these surge limiters and provides information and performance data for their application.

Increased transformer winding losses are an important consideration in determining the overall impact of harmonic currents in a power system. Frequently, losses due to harmonic currents are assumed to vary with the square of frequency. The purpose of this paper is to compare winding loss calculations from a finite element method with measured losses in single phase distribution transformers and to test the principle of superposition of harmonic losses due to nonsinusoidal currents. The results confirm both the finite element method and the principle of superposition. Furthermore, it is shown that, due primarily to inaccuracy in measuring 60 Hz eddy current losses, application of the commonly accepted frequency squared rule can yield overly pessimistic loss predictions for typical power system harmonic frequencies.

This paper reviews the technical problems anticipated in the design construction and operation of HVDC converter stations in the voltage range ± 600-1200 kV. It is based on a literature review and discussions with experts from manufacturers and utilities. It concludes that 800 kV is a clearly feasible voltage step with existing knowledge, 1000 kV is practicable with further research effort, but that 1200 kV is unlikely to be economically feasible without a technological breakthrough. The principal problems identified are: 1) The behaviour of external insulation in bad weather, especially in polluted situations 2) Transformer insulation Controlled gas insulation 3) Surge arrester limitations Methods of controlling overvoltages.

The important considerations that lead to a specific HVDC valve design for a given application are often not well appreciated. In this paper, voltage and current stresses on HVDC valves are discussed in the context of their importance in relation to the capabilities and limitations of modern power thyristors. It is concluded that a better understanding of the stresses and their implications on valve design will lead to improved specification, design and testing of valves for HVDC.

The paper provides guidelines for performing switching surge field tests on EHV systems. Objectives for the field tests are identified. Requirements for the test plan, test procedures, instrumentation, and test documentation are analyzed. The paper is the result of initial work towards development of a more comprehensive guide on this topic.

Optical Static Wire has become a widely-used means of providing optical communication links along utility right-of-ways. Our initial concept consisted of a welded aluminum pipe, which provided physical and environmental protection for the optical fibers contained therein. This paper presents the results of the development of a helically channelled solid aluminum core construction for the positioning of loose buffered optical fibers. This second generation cable design eliminates many of the disadvantages encountered with the first generation design. The technical features of the loose buffer tube design and performance characteristics of the completed cable are discussed.

Previous papers have described a method for the detection of arcing fallen distribution primiary conductor faults using the electrical noise in feeder current above 2kHz. While this method provided improved detection of such faults, this high frequency signal often would not propagate past capacitor banks. In the present paper, we describe a technique for the identification of arcing high impedance faults using burst noise signals at frequencies near the power system fundamental and low order harmonics. Arcing generates non-synchronous burst noise signals which approximate white noise, providing a signal which can be differentiated from synchronous power system signals in the frequency bands of interest. The primary advantage of monitoring frequencies near the fundamental is that this arcing fault signal at low frequencies will exhibit little attenuation from capacitor banks or other sources. This paper provides preliminary results that arcing faults can be detected effectively using frequency components below 60 Hz or between low order harmonics of 60 Hz. The technique is demonstrated through analysis of analog signals recorded during numerouis staged utility downed conductor tests.

This paper discusses the breaking ability of an air blast circuit breaker (ABB) or SF6 gas circuit breaker (GCB), and the interrupting phenomena around current zero in the case where a resistor or capacitor is connected in parallel with its interrupter to improve the breaking ability. It has been clarified that the use of a parallel resistor for ABB, and that of a parallel capacitor for GCB are the most effective methods to improve the breaking abilities; the parallel resistor not only serves to reduce the rate of rise of the transient recovery voltage (rrrV), but also shifts the current from the interrupter to itself around the current zero, thus reducing the stress for interruption. The improvement of the breaking ability is achieved by reducing the initial average rrrV between zero and 1 microseconds (inherent value), when the parallel capacitor is used with the GCB.

This paper addresses the accuracy of 3-phase transformer loss testing with particular attention to the reliability of manufacturers' certified loss test results. Seven three-phase padmounts, one from each of seven different manufacturers, were used in a round-robin test program. In addition to their original production tests, each of the seven manufacturers performed loss tests on the entire group of transformers. The results of the program indicate an uncomfortably wide range of results.