Development of a single phase prepaid Electrical Energy Meter using 89S8252 microcontroller architecture
The Electricity Company implements the `Prepaid Electrical Energy Meter (PEM)' scheme among the electricity consumers to meet the objectives of: (i) collecting advance money and (ii) motivating the customers to make conservative use of electricity. The 2nd objective can be effectively achieved with an indoor type PEM fitted with 7-segment bright display unit. The meter designer aims, using appropriate hardware modules and software routines, to guide the PEM for cycling through the following steps: (i) deduct cost of every 0.01kwhr energy consumed, (ii) display balance, (iii) check balance, (iv) disconnect load at zero balance, (v) issue alarm signal to engage correct prepaid card, (vi) read the prepaid card, (vii) zeroing the prepaid card, (viii) update balance, (ix) save balance in nonvolatile EEPROM at power failure, and (x) retrieve balance from EEPROM at power resumption. This paper has described, based on extensive experiments on real hardware using AT89S8252-ADE7755-AT90S2313 chip set, the implementation methodology of a PEM with bright display unit. A prototype meter has been built, tested and found to work as per standard specifications.
Prepaid energy meters network via power system communication
This paper presents a new idea of designing a prepaid energy meters that has the ability of being connected to a unified centre (Energy Company). The process of connecting the meters to a unified centre can facilitate the security, control and maintenance purposes. The mentioned network is economical because it is established using the existing power lines instead of constructing a new wired or wireless network. The data are transmitted over this network using Power Line Communication (PLC) technology. A special device is used to inject the data to the network and captures them from the network; this device is the power line communication modem. A simple design of the network is done using two computers and two modems (PLM) plus a program code. By using a modem the program can take the measured data from the meter then send them to the computer server and vice versa. The designed network makes the energy company able to access any prepaid energy meter in the unified area and control the measurements of this meter; and as a result, stealing of electricity can be prevented. Also company can communicate with the consumer by sending text messages such as a serial number for recharging the energy or alarm the consumer before the whole amount of electricity is totally consumed. Moreover, this network offers the ability of controlling the supply of energy such as switch “On” or “Off” of the electricity supply.
HYPERGOLIC REACTION MECHANISMS OF CATALYTICALLY PROMOTED FUELS WITH ROCKET GRADE HYDROGEN PEROXIDE
Abstract The coupling of the physical and chemical processes controlling the ignition delays (τ ign ) of hypergolic propellants complicates the direct analysis of the transient ignition processes. The transport properties of both the propellants and the ambient gas, and the heat of vaporization and reaction affect τ ign and must be considered experimentally. Furthermore, since hypergolic ignition occurs, by definition, on contact, the mechanics of initial contact and subsequent mixing can affect τ ign and must also be considered. Experimental results from a study of the hypergolic ignition of a catalytically promoted fuel with rocket grade hydrogen peroxide (RGHP) are presented. Statistical analysis of the experimental data was conducted to evaluate the relative effects of RGHP concentration, initial ambient pressure, and the ambient gas on τ ign . At RGHP concentrations of less than 92% in water, stable ignition was difficult to achieve. At sufficiently high Lewis number, an oscillatory ignition process is observed. A phenomenological model comprising mixing, RGHP decomposition, fuel heating and vaporization, and auto-ignition is presented and compared to the experimental results.