The response of stranded cables to exciting forces produced by wind is studied here, and details of an analytical and experimental study of cable self-damping are presented.

Mathematical Analysis of Transmission Line Vibration

A phenomenological transmission line corona model is proposed in this paper which accommodates the diverse aspects of steady-state and transient power and energy losses and change in capacitance. Single phase line sections have been represented by a nonlinear model circuit which changes its state depending on the present and the previous values of the voltage. Propagation with corona is simulated by cascading identical model circuits and the nonlinear transmission line equations are solved by a finite difference method. The charge-potential characteristics of line sections and the nonlinear propagation characteristics of voltage surges computed numerically from our model conform with available experimental data in the literature.

A Nonlinear Circuit Model for Transmission Lines in Corona

With the application of surge tests to high voltage electrical apparatus, the question of the measurement of high-surge voltages has become a subject of prime importance. It is accordingly desired in Part I to show the practical work done in the laboratory at Sharon to calibrate the measuring devices, and in Part II to study the more interesting fundamental relationships that affect the operation and accuracy of these measuring devices. The methods of voltage measurement used are the resistance potentiometer, capacity potentiometer, and sphere gap. The potentiometers serve as dividers of the high-surge voltages for measurement at the cathode-ray oscillograph. The resistance potentiometer is a fundamental standard but requires consideration of its limitations for very rapid phenomena. In cases where these can be compensated for or are negligible, the resistance potentiometer method is very desirable. The capacity potentiometer is a secondary standard which can be calibrated. If corona and oscillations can be eliminated, it is a very desirable method of measurement, inasmuch as it is less subject to distorting the wave shape of the surge. The sphere gap is useful as a secondary standard for occasional check measurements, and it is of interest that formulas derived from smaller gaps still hold, as indicated by the check between the calculated curve for the 200-cm sphere gap and the calibration points with the resistance potentiometer.

The Measurement of High-Surge Voltages

Wind Tunnel Investigation of Conductor Vibration with Use of Rigid Models [includes discussion]

This paper presents a method to calculate the corona power loss and the ground level electric field values for single- and three-phase power transmission lines. The charge simulation technique is applied in which the surface charge on the stressed conductor(s) as well as the space charges around each conductor are represented by a discrete set of unknown infinite line charges. Satisfying the properly chosen boundary conditions at the transmission line conductors results in a system of linear algebraic equations whose solution evaluates the unknown line charges. The emission of ions from a conductor surface is assumed to take place when the magnitude of the charge simulating its surface charge exceeds an onset value based on the predetermined onset field values for both positive and negative half cycles. The simulation space line charges are displaced back and forth to the conductor by the action of the electric field whose magnitude and direction depends on the simulation charges in the conductor and in the surrounding space. Recombination process takes place whenever charges of opposite polarities meet together. The calculated corona power loss for single- and three-phase power transmission lines agreed satisfactorily with those reported earlier.

http://iopscience.iop.org/article/10.1088/0022-3727/27/12/019/pdf

A charge simulation based method for calculating corona loss on AC power transmission lines

Corona loss measurements were obtained on conductors of three different diameters; namely, 1.125 in., 1.49 in. and 2.0 in. Voltages up to 600-kv. line voltage were used in these measurements. Various surface conditions of the 1.125-in. cable were studied. These measurements include tests on the new cable as received, the cable as washed, scratch brushed, buffed and dragged. The aging of the dragged cable was observed for seven months. Data were obtained on the daily variation of loss. The effects of configuration and transposition were studied on No. 22 wire. A description of the modifications in the high-voltage wattmeter for these high-voltage measurements is reported.

Corona Loss Measurements for the Design of Transmission Lines to Operate at Voltages Between 220 Kv. and 330 Kv.

A qualitative analysis of the nature of the space charge created about a conductor in corona, particularly with respect to relative magnitudes and polarities, rather than actual quantitative measurement, is described here. This work was the principal work on corona during the past year in the Ryan High-Voltage Laboratory. In tests with the arrangements of a wire and a plane, and of a wire and a cylinder, a decided rectifying effect was discernible in the space about the conductor in corona, in that that region was built up to a unidirectional potential above ground, the magnitude and polarity of this potential depending on the voltage applied. In both of these set-ups, this net rectification, which is evidently caused by some differential action entering into the ionization process, was of a positive sign at the start of corona, but changed over to negative as the voltage was raised. In a test made on two 1.1-in. diameter, parallel concentric strand copper conductors, 1O ft. apart, the space between them was found to have assumed a potential above ground when the conductors were in corona, the sign of this charge being negative at first, and then positive as the voltage increased. Tests were also carried out on a single brush, and on a rod fitted with ``artificial'' brushes.

The Space Charge That Surrounds a Conductor in Corona

A description is given of the apparatus for the measurement of power as low as a fraction of a watt at power factors approaching zero and voltages as high as 175 kv to neutral A standard make of portable wattmeter was used having maximum ranges of 15 watts, 375, 75 and 150 volts and 20 per cent power factor To this wattmeter was adapted a three-megohm water column resistance multiplier In the original form of the wattmeter the origins of certain errors, due to capacitances chiefly, were studied and methods for their elimination were subsequently determined Integrity tests were developed by which the values of error powers were obtained and used as guides in making subsequent adjustments for the reduction of such errors to zero These integrity tests were checked by using the wattmeter for the measurement of known amounts of power Reconnaissance studies were made of the voltage-corona power loss relations for rope laid copper, 091-in, lock wire smooth copper, 091-in and concentric strand aluminum, 1006-in diameter transmission line conductors in rain and fair weather at differing degrees of humidity, temperatures, and barometric pressures, from ``initial'' to ``full'' corona formation This class of studies was extended to corona loss values as offered by a wide variation of the ``surface roughness'' of conductors subjected to high voltages The losses for a single brush were measured and the shielding effect of groups of brushes was studied Losses to single strings of insulators under different conditions were determined

Power Measurements at High Voltages and Low Power Factors

Corona loss measurements were made on seven different conductor specimens. The losses were measured directly, on a three-phase line 700 ft. long, by means of three single-phase high-voltage wattmeters. The object of the test was to obtain data for the choice of conductor to be used on a 220-kv. 60-cycle line. The results show the effect of weathering of conductors, the comparison of conductors of two different diameters, the effect of size of strands and the method of stranding and also the effect on new conductors of the change in surface conditions caused by rain and washing.

Corona Loss Measurements on a 220-Kv. 60-Cycle Three-Phase Experimental Line

A sequel to an earlier paper by Carroll and Cozzens concerning corona loss measurements for the design of transmission lines, this paper presents data resulting from comparative tests on 6 different designs of 1.4-in. conductor, the size selected for a 275-kv transmission line from Boulder Dam to Los Angeles. Data covers 3-phase, single-phase, and rain tests, and adds materially to the corona loss data previously reported.

Joseph S. Carroll

Papers

Corona Loss Measurements for the Design of Transmission Lines to Operate at Voltages Between 220 Kv. and 330 Kv.

The Space Charge That Surrounds a Conductor in Corona

Power Measurements at High Voltages and Low Power Factors

Corona Loss Measurements on a 220-Kv. 60-Cycle Three-Phase Experimental Line

Corona Losses From Conductors of 1.4-Inch Diameter