Laser sensor for detection of SF6 leaks in high powerinsulated switchgear systems

A novel photoacoustic spectrometer (PA) has been developed for in-situ detection of SF₆ leaks in low concentrations. The developed system is equipped with a sound alarm system and has been tested in the laboratory for very minute SF₆ leaks. This newly developed SF₆ detection device utilizes a high quality factor resonant photoacoustic cell and continuous wave (CW) line tunable CO₂ laser at 10.55 μm wavelength. Whenever SF₆ is detected an acoustic signal is generated and no signal appears from ambient air if there is no leakage of SF₆. An electret microphone is used for the detection of these acoustic signals. The system is capable of detecting leaks of the order of 3.5 ppbv (parts per billion by volume) concentration. This device has been proved to have significant applications to industrial organizations that have electric power gas insulated systems (GIS). It could be also applied for other applications such as monitoring of environmental pollutants with minimal adjustments     

Speed control of a three-phase induction motor based on robust optimal preview control theory

A synthesized method for speed control of a three-phase induction motor (IM) based on optimal preview control system theory is implemented in this article. An IM model comprises three-input variables and three-output variables that coincide with the synchronous reference frame that is implemented using the vector method. The input variables of this model are the stator angular frequency and the two components of the stator space voltage vector, whereas the output variables are the rotor angular speed and the two components of the stator space flux linkage. The objective of the synthesized control system is to achieve motor speed control, field orientation control, and constant flux control. A novel error system is derived and introduced into the control law to increase the robustness of the system. The preview feed-forward controller, which includes the desired and disturbance signals, is used to improve the transient response of the system. A space vector pulse-width modulation (PWM) control technique for voltage source-fed IM is prepared for microprocessor-based control. Spectral analysis of the output voltage is evaluated to predict the effect of the proposed space vector modulation technique on the dynamic performance of the IM. The optimal preview controlled system is implemented, and its applicability and robustness are demonstrated by computer simulation and experimental results.     

A power line data communication interface using spread spectrumtechnology in home automation

Building automation technology is rapidly developing towards more reliable communication systems, devices that control electronic equipment. This equipment, if controlled, leads to efficient energy management, and savings on the monthly electricity bill. Power line communication (PLC) has been one of the dreams of the electronics industry for decades, especially for building automation. It is the purpose of this paper to demonstrate communication methods among electronic control devices through an AC power line carrier within the buildings for more efficient energy control. The paper outlines methods of communication over a power line, namely the X-10 and CE bus. It also introduces the spread spectrum technology as to increase speed to 100-150 times faster than the X-10 system. The power line carrier has tremendous applications in the field of building automation. The paper presents an attempt to realize a smart house concept, so called, in which all home electronic devices from a coffee maker to a water heater microwave to chaos robots will be utilized by an intelligent network whenever one wishes to do so. The designed system may be applied very profitably to help in energy management for both customer and utility     

Base load fuel consumption with radiant boiler simulation

The authors demonstrated by means of simulation software that the boiler design setpoint was critical to fuel consumption and optimum output megawatts. The software simulated a Babcock and Wilcox Carolina-type radiant boiler unit with defined characteristics. The process simulation was based on a dynamic model of the boiler and associated plant components. A systematic approach was developed to study many cases of the relationship between the drum pressure and the output megawatts for typical loads. The relationship between the steam flow and the output megawatts is discussed. The cases were studied by maintaining a constant fuel flow and operating under several steam throttle conditions. This radiant boiler was most efficient with respect to throttle conditions when operated at 1005°F and 2400 PSIA, the design setpoint     

Estimation of lightning impulse insulation strength of two seriesdielectrics using the least square technique

In this paper, the least square (LS) estimation technique was used to estimate the total critical flashover (CFO) for combinations of two insulating materials from the experimental data obtained. This method had acceptable accuracy when applied to the total population of the two-component combinations but lost some accuracy for some of the sub-sets of the two materials