May be next to
Sunday, June 29, 2008
Saturday, June 28, 2008
Saturday, June 21, 2008
Marking 60th birthday of world's first digital computer, here are some photos of the earliest computers of the world
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It took 52 minutes to compute a mathematical problem. Here is the modern computer.
Great revolution in computers................................................
Friday, June 20, 2008
Friday, June 13, 2008
Electricals - Current Transformer
Central to all of the AC power transducers is the measurement of current. This is accomplished using a current transformer (CT), a "donut" shaped device through which is threaded the wire whose current is to be measured.
A current transformer is designed to produce either an alternating current or alternating voltage proportional to the current being measured. The CTs used with the Wattnode transducers produce a 333 mV alternating voltage when the rated current is measured (either 30A, or 50A). The OSI power transducers employ CT's that produce 5V output at rated value.
All of the 15 CT's employed in the energy monitoring system are "split core." This allows the CT to be opened, installed, and closed, without disconnecting the circuit to which they are attached.
Electricals - Energy Meter Test.
Energy meter test equipment is used to test energy meters that measure the correct amount of energy recorded, usually in kilowatt-hours or cubic feet of natural gas consumption.
An energy meter is a device that measures the amount of energy supplied to a residence or business. These are customers of either an electric or natural has or oil supply company.
Energy utilities record these values measured by energy revenue meters to generate an invoice for the energy consumer. In the case of electricity, energy meter test equipment can also record other variables including the time of day (hence the term "time-of-use meters") when the energy was consumed.
Modern electricity meters operate by continuously measuring the instantaneous voltage (volts) and current (amperes) and finding the product of these to give instantaneous electrical power (watts) which is then integrated against time to give energy used (joules, kilowatthours etc). These electricity meters fall into two basic categories, electromechanical and electronic.
Electricity meter test equipment is used to determine the accuracy of energy meters that automatically record the time for any given number of revolutions (up to 99) of an electricity meter. The number of revolutions which it is desired to count is set on the dials. Each revolution of the meter element transmits an impulse to the counting mechanism through the medium of a photoelectric cell. A stopwatch is started by the first impulse after closing a starting switch and is stopped when the predetermined number of revolutions has been completed.
Energy meter test equipment are also used to test electronic meters which enable data processing for complex tariffing purpose, mainly two-way communication for remote energy meter reading and intelligent load control for efficient energy use.
In spite of Energy meter test equipment being used to maintain the accuracy of these energy meters, there is still a certain level of mistrust in using intelligent metering widely in many countries. In order to overcome these major disadvantages, energy meter test equipment is integrated in intelligent electricity meters for daily examination of correct operation.
Electricals- Power Quality Analyzer
A power quality anayzer is used to measure electric power signals to determine the load's ability to function properly with that electric power. Without the proper electric power, an electrical device (or load) may malfunction, fail prematurely or not operate at all. There are many ways in which electric power can be of poor quality and many more causes of such poor quality power.
Power quality analyzer technology tracks several electrical parameters, which include AC voltage, AC current, and frequency. Electrical parameters include demand and peak demand. Electrical demand is the actual amount of power that the monitored system uses. Peak electrical demand is the maximum amount of electric power that can be used. Typically, power parameters are measured in watts (W), volt amperes (VA), and volt ampere reactives (VAR). Watts are units of electrical power that indicate the rate of energy produced or consumed by an electrical device. Volt amperes equal the current flowing in a circuit multiplied by the voltage of that circuit. Volt ampere reactives identify the reactive component of volt amperes.
Power quality analyzers detect mystery disturbances: those upsets to a process or sensitive equipment operation that don't seem to correspond to any identifiable source of power disturbance. Such things as ground loops, high speed transients, lightning, and common mode electrical noise come to mind. Many of these events are here and gone in such a short time frame that they are not easily identified, except with a power disturbance analyzer using highspeed wave shape or event capture.
A power quality analyzer can also detect repetitive, cyclical disturbances both within and outside of a facility. These problems will be repetitive and cyclical in nature, definitely power-related, and line-to-line. Examples include voltage sags and surges, momentary interruptions by circuit breaker operations, and power interruptions.
A power quality analyzer can also measure harmonic distortion, a disturbance related to the integer multiples of the fundamental power frequency (60 Hz). WIt is widely recognized that this area is a subset of the power related area, since harmonic currents and voltages are recurring. However, there may need to be special tactics in searching out these problems and identifying our solution alternatives.
Thursday, June 12, 2008
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