PTC thermistor protects multiloaded power supplies

A PTC /Positive-Temperature-Coefficient/ thermistor placed in series with each branch load of a multiload circuit prevents power loss in parallel branches. This thermistor may be used in any circuit requiring current limiting or intended overload resetting

Westinghouse programs in pulsed homopolar power supplies

This document details Westinghouse's ongoing study of homopolar machines since 1929 with the major effort occurring in the early 1970's to the present. The effort has enabled Westinghouse to develop expertise in the technology required for the design, fabrication and testing of such machines. This includes electrical design, electromagnetic analysis, current collection, mechanical design, advanced cooling, stress analysis, transient rotor performance, bearing analysis and seal technology. Westinghouse is using this capability to explore the use of homopolar machines as pulsed power supplies for future systems in both military and commercial applications

Simplified power supplies for ion thrusters

The initial development and demonstration of power supplies with an order of magnitude reduction in parts count, leading to increased reliability at lower weight, while still maintaining thrust system performance are discussed. Two new self-regulating keeper power supply circuits were developed and tested. One supply comprises 14 parts and uses an input voltage range of 18 to 36 volts, the other operates from 200 to 400 volts and requires 22 components. A technique for controlling heater power is also demonstrated

Development of an AC-DC boost power factor correction

With rapid development in power semiconductor devices, the usage of power electronic systems has expanded to new and wide application range that include residential, commercial, aerospace and many others. Power electronic interfaces such as switch mode power supplies have proved to be superior over traditional linear power supplies. However, their non-linear behavior puts a question mark on their high efficiency. The current drawn by the switch mode power supplies from the line is distorted resulting in a high Total Harmonic Distortion and low Power Factor. Power Factor, the ratio between the real or average power and the apparent power forms a very essential parameter in power system. It is indicative of how effectively the real power of the system has been utilized. With the stringent requirements of power quality, power factor correction has been an active research topic in power electronics, and significant efforts have been made on the developments of the power factor correction converters. This project aims to develop a circuit for power factor correction using active filtering approach by implementing boost converters arranged in parallel. It shall be based on an optimized power sharing strategy to improve the current quality and at the same time reduce the switching losses. The simulation result shows that the power factor was improved when the power factor corrector circuit added to the inverter and the power factor corrector circuit switching with proportional-integral-derivative controller shows better power factor then using pulse width modulation switching mode

Extended operating range of the 30-cm ion thruster with simplified power processor requirements

A two grid 30 cm diameter mercury ion thruster was operated with only six power supplies over the baseline J series thruster power throttle range with negligible impact on thruster performance. An analysis of the functional model power processor showed that the component mass and parts count could be reduced considerably and the electrical efficiency increased slightly by only replacing power supplies with relays. The input power, output thrust, and specific impulse of the thruster were then extended, still using six supplies, from 2660 watts, 0.13 newtons, and 2980 seconds to 9130 watts, 0.37 newtons, and 3820 seconds, respectively. Increases in thrust and power density enable reductions in the number of thrusters and power processors required for most missions. Preliminary assessments of the impact of thruster operation at increased thrust and power density on the discharge characteristics, performance, and lifetime of the thruster were also made

Laser power conversion system analysis, volume 1

The orbit-to-orbit laser energy conversion system analysis established a mission model of satellites with various orbital parameters and average electrical power requirements ranging from 1 to 300 kW. The system analysis evaluated various conversion techniques, power system deployment parameters, power system electrical supplies and other critical supplies and other critical subsystems relative to various combinations of the mission model. The analysis show that the laser power system would not be competitive with current satellite power systems from weight, cost and development risk standpoints

Union Power, Minimum Wage Legislation, Endogenous Labor Supplies and Production

The objective of this work is to study the impact of the unions bargaining power on production and wages. We present a model where a competitive final good is produced through two substitutable intermediate goods, one produced by unskilled labor and the other by skilled labor. Potential workers decide at their cost to become skilled or unskilled and, thus, labor supplies are determined endogenously. We find that the reallocation of the labor supplies due to changes in the unskilled (or skilled) unions bargaining power may have a positive impact on the final goods production. At the same time, total labor earnings increase with the unskilled unions bargaining power if the final goods production increases too. We also show that the minimum wage legislation has e.ects similar to an increase in the bargaining power of the unskilled unions.skills, labor supplies, minimum wage, union power

Zener diode is starter for transistor regulated power supply

Zener diode in parallel with a silicon transistor supplies the starting current for a transistor-regulated power supply

Power supplies and accelerators

The paper is intended to provide an introduction to the magnets employed in a circular particle accelerator to bend and steer the charged-particle beam. These are the principal loads that power converter engineers will encounter and the basic concepts of the accelerator lattice are presented, without assuming any prior knowledge. The interface with the power converters is examined and the need to optimize the supply and the load together is highlighted