Constant Resistive Load Research Articles

Load test on superconducting transformer and fault current limiting devices for electric power system

A superconducting fault current limiting transformer has been investigated to find out its feasibility. In general, the following two types of superconducting fault-current limiters could be expected: noninductive two-port and four-port devices based on superconductive-to-normal state transition. The authors have investigated the transient phenomena in the transformer and then designed a 10 kVA superconducting fault current limiting transformer. First of all, in order to understand performances during quenching in the main coils of the transformer at power system faults, no-load and short-circuit tests in the auxiliary coils were performed. With the same test for the main coils and four windings, exciting conductance, susceptance and leakage impedance were estimated. Under a constant resistive load, actual load tests and sudden short-circuit tests were carried out. Test results are presented. >

Resistive signal line wiring net designs in multichip modules

To approximate the frequency dependence of the characteristic impedance and signal attenuation of a DC resistive transmission line, formulas with one pole and one zero on the negative real axis are proposed. The algebraic time-domain solutions for the near-end and far-end voltages of this line, which is driven by a constant resistance source, are derived. The far end of this line is either open-circuited or terminated by a constant resistance load. Nomographs to guide the multichip module (MCM) wiring net designs are developed and presented. Their application is illustrated by an MCM-D address bus wiring net design example.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Grating lobes in the scattering patterns of edge-loaded strips

The scattering patterns from perfectly conducting strips with constant resistive edge loads have periodic grating lobes that rise above the reduced relative sidelobe levels. These grating lobes are a function of the resistive load width and seriously limit scattering sidelobe reduction. Neither tapering the resistivity of the load nor adding more resistive loads of the same width will further reduce the maximum sidelobe level. Equations for predicting the size and location of the grating lobes are derived. In addition, optimum edge loads that produce the smallest maximum sidelobe level are derived.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Lithium batteries utilizing SOCl 2[sbnd]SO 2Cl 2 mixed electrolytes

The performance of C-size commercial cells containing mixtures of SOCl 2 SO 2Cl 2 mixed depolarizers with 1.0 and 1.8 M LiAlCl 4 has been compared with that of Li/SOCl 2 cells as a function of discharge temperature. Fresh cells as well as those stored at 70 °C were discharged at constant resistive loads equivalent to 1 and 10 mA/cm 2 at 25, 0 and −30 °C. Cell capacity, voltage regulation and start-up characteristics were found to depend on storage, SOCl 2/SO 2Cl 2 ratio and LiAlCl 4 concentration. The mixed depolarizer cells had superior performance at the lower discharge temperatures and after storage. The behavior of metal phthalocyanine catalysts was evaluated in 1.8 M LiAlCl 460/40 SO 2Cl 2/SOCl 2 electrolyte at 10 mA/cm 2 at 25 °C after storage at 70 °C. The NiPc and CuPc catalysts improved overall cell performance.

The Relationship of Torque, Velocity, and Power with Constant Resistive Load During Sagittal Trunk Movement

Strength and fitness studies have been used to determine the predictability of back pain episodes. Tests have demonstrated that isometric strength displays little prognostic value in the development of low-back pain. Static isometric tests have achieved widespread usage due to the simplicity and safety of protocols, the readily available technology, and the low administrative costs. Dynamic lifting models have, however, predicted significantly higher spinal loads than those derived from static models. The objectives of this study were twofold: to investigate the relationship of the torque, velocity, and power to the resistive load during trunk flexion and extension, and to develop predictive models for these relationships for the subject's performance of the 10th, 50th, and 90th percentile distribution. The results of the study found that the flexion/extension torque had a positive linear correlation with the set resistance; the velocity displayed a negative linear correlation, while power had a quadratic relationship with the resistance.

Harmonic analysis of a capacitor‐filtered rectifier with line impedance

AbstractAlthough the amount of harmonics generated from home electronic equipment such as televisions is small, the number of sets is large and they are used at the same time. Therefore, the harmonics generated from the power supplies of the electronic equipment is a cause of harmonic interference in the power distribution systems [1, 2]. In this paper, the input current of a capacitor‐filtered rectifier used widely as a power supply for electronic equipment is calculated with the impedance of the distribution system taken into consideration. As a result, an accurate expression became possible for the capacitor‐filtered rectifier current which had been treated by means of an approximate equation in the case where a line impedance, particularly inductance, exists [1, 2]. Also, an accurate prediction became possible for the current waveforms and harmonic behaviors according to the variations of the circuit parameters. The results computed as the parameters are varied indicate that the diode current path width, current waveforms and harmonic distributions, are strongly dependent on the inductance variation. The load circuits of a constant‐resistance type and of a constant‐power type were studied. As the inductance is increased, the harmonics are decreased whereas the amplitude and the average power of the fundamental wave are also decreased in the case of a constant resistance load. On the other hand, in the case of a constant power load, the amplitude of the fundamental wave tends to increase as the inductance is increased. When several of the capacitor‐filtered rectifiers are connected in parallel to a power distribution system, the amplitude of the harmonic cannot be evaluated by a linear sum of the harmonic contents of individual rectifiers.

The technology of the Li/Cl2 in SO2Cl2 cell system IV. high temperature performance, storability, and safety characteristics

Tests were conducted to determine the performance, storability, and safety characteristics for specially designed Li/Cl2 in SO2Cl2 (Li/CSC) cells at temperatures as high as 150° C. Discharge tests at 150° C showed that practical Li/CSC D cells yield energy densities of 0.75 to 0.91 Wh cm−3 for constant resistive loads of 3.0 to 75.0 ohms, respectively. Further, the performance results obtained for cells stored at 150° C and either discharged at 25° C or discharged at 150° C showed little loss in realized capacity but exhibited a noted loss in rate capability. These cells have been subjected to abusive conditions such as short circuit, forced overdischarge, incineration, puncture, and shock sensitivity testing following prolonged discharge at both ambient and elevated temperatures. Safety/hazard testing has also included specific combinations of the above abusive conditions. The results relative to the safe, efficient use of the cells at elevated as well as room temperatures will be discussed.

Effects of added inspiratory loads on load detection thresholds.

To examine the effects of continuously added background inspiratory loads on the difference thresholds for resistive (delta R50) and elastic load detection (delta E50), 12 healthy subjects were studied. The results showed that, whereas the addition of a constant background elastic load significantly altered delta R50, the addition of a constant background resistive load did not significantly affect delta E 50. These results can be explained on the basis that the addition of a constant elastic load alters the total sensory information a midbreath, where resistive load detection occurs, but the addition of a constant resistive load does not affect elastic load detection, which occurs at the end of the breath where flow-dependent information is minimal.

Pulse-forming networks with time-varying or nonlinear resistive loads

High-power pulse-forming networks (PFN) have been in use for some time. The networks are usually designed using techniques that assume a desired pulse shape and a constant resistive load. High-power gaseous discharge devices have created a need for high-power pulse generation operating into time-varying resistive loads or nonlinear resistive loads. Although some work has been done in designing a PFN with a time-varying load, little has been done for the nonlinear loads in general. In this paper a study of the effects of a type-varying or nonlinear load on a PFN is presented using simulation techniques. The resultant output pulse is compared to the desired pulse using different error functions, such as mean-square error and absolute error. The sensitivity of the error function with respect to the parameters of the PFN is determined. A criterion is developed for the adjustment of the parameters of a PFN to improve the pulse delivered to a time-varying or nonlinear resistive load. The form of the desired pulse, the error function, and the type of resistive load can be varied to obtain a specific adjustment criterion. In one case, applying the technique to a given PFN resulted in a 46.4-percent improvement in mean-square error.

Operation of self-excited generators for windmill application

The paper deals with the operation of self-controlled wound-field generators for small-scale wind-power application in which the output is connected to a constant-resistance load and the field is connected in plain shunt or series. It is shown that, with this configuration, a fairly good natural match can be obtained between the power/speed characteristics of the generator and the windmill, particularly when the magnetic circuit of the generator goes fairly hard into saturation at higher speeds and field currents. Test results are included and indicate that an external d.c. source would often be necessary to initiate ‘build-up’ in a practical system.

Stepped Voltage Dc/Ac Inverter --Part I: Analysis

A DC/AC inverter whose voltage is constructed from discrete low level DC sources to form a stepped sine-wave-like output is introduced. The criterion of optimal approximation of the stepped waveform to a sinewave was the minimum mean square error. The internal resistance of the generated source voltage is time varying since the total series resistance changes with the wave shape. When a constant resistive load is connected to such a load, the load voltage shape does not follow the source voltage and the optimal approximation to a sinewave of the two voltages will depend on two different switching policies: one adaptive to the source voltage and the other adaptive to the load voltage'. The inverter operation for both cases is analysed, and the main harmonic voltage and power, harmonic spectrum and distortion are obtained. The proposed inverter has superior properties characterized by its low distortion and high efficiency.

A Simple Combining System for Two High-Power HF Transmitters

A symmetrical, linear, four-wire system in a special hybrid configuration provides a simple method for combining the balanced output of two transmitters operating on the same frequency and feeding the combined output power to a common balanced load. Due to its simplicity of operation, economy of construction, power capability, and broad-band characteristics, this combiner provides significant advantages over the conventional lumped-constant combiners that are commonly used for combining high-power transmitters. It provides complete protection in the event of failure of either transmitter without affecting the input impedance or operation of the other; and, given a constant resistive load equal to Z4/2, it will take power at any frequency up to about 30 MHz. If symmetry is realized in practice, the two tuning adjustments may be mechanically coupled to reduce the operating controls to one. An analysis of the system demonstrates that the distributed voltages and currents for two 50-kW transmitters fall well within practical limits, and that with careful design, it is applicable for combining the outputs of transmitters as large as are presently being built. Such a combiner has been constructed for two high-frequency, 50-kW, broadcast transmitters at the Radio Free Europe transmitter plant near Biblis, Germany, and its performance characteristics confinn the theoretical expectations.

The input impedance of rectifier modulators

It is shown how the input impedance of a rectifier modulator of series, shunt or ring type can be calculated, and a large number of cases are tabulated, assuming (a) that the terminating impedances, while being as frequency selective as desired, are nevertheless purely resistive at all modulation-product frequencies where they are not zero or infinite, and(b) that the rectifiers have a square-wave variation of resistance with time. It is clearly shown that in all cases except one (i.e. a ring modulator with constant-resistance load) the input impedance-defined as the ratio of the input voltage to the input current at the applied signal frequency-has the peculiar property of being dependent on the nature and magnitude of the signal-source impedance from which it is being measured.