General theory on Elecrical:-direct current: alternating current: three phase?

Question

voltage: current: watts: r.c.b: m.c.b: e.l.c.b:
multimeter: insulation tester: avometer

Answer 1

Direct current is considered as the constant flow of electrons in the single direction from low to high potential. This is typically in a conductor such as a wire, but can also be through semiconductors, insulators, or even through a vacuum as in electron or ion beams. In direct current, the electric charges flow in the same direction, distinguishing it from alternating current (AC).

An alternating current (AC) is an electrical current whose magnitude and direction vary cyclically, as opposed to direct current, whose direction remains constant. The usual waveform of an AC power circuit is a sine wave, as this results in the most efficient transmission of energy. However in certain applications different waveforms are used, such as triangular or square waves.

In electrical engineering, three-phase electric power systems have at least three conductors carrying voltage waveforms that are 2π/3 radians (120°,1/3 of a cycle) offset in time.

Voltage is the difference of electrical potential between two points of an electronic circuit, expressed in volts. It is a measure of the capacity (not the technical meaning) of an electric field to cause an electric current in an electrical conductor. Depending on the difference of electrical potential it is called extra low voltage, low voltage, high voltage or extra high voltage.

Electric current is by definition the flow of electric charge. The SI unit of electric current is the ampere (A), which is equal to a flow of one coulomb of charge per second.

The watt (symbol: W) is the SI derived unit of power, equal to one joule per second. A human climbing a flight of stairs is doing work at the rate of about 200 watts; a highly-trained athlete can work at up to approximately 2000 watts for brief periods. An automobile engine produces 25 000 watts (approximately 30 horsepower) while cruising. A typical household incandescent lightbulb uses 40 to 100 watts.

A multimeter or a multitester is an electronic measuring instrument that combines several functions in one unit. The most basic instruments include an ammeter, voltmeter, and ohmmeter. Analog multimeters are sometimes referred to as "volt-ohm-meters", abbreviated VOM.

An insulator is a material or object which contains no free electrons to permit the flow of electricity. When a voltage is placed across an insulator, no charge/current flows.

there are many types of testers but mainly a tester is used to know source of high voltage or about current etc..

The Avometer was a British brand multimeter (USA). It was often called an AVO and derived its name from the first letter of the words amperes, volts, ohms. The instrument had an accuracy of ±1% of FSD on DC ranges and ±2% on AC ranges. Its maximum current consumption was 50 μA (corresponding to 20,000 ohms per volt), which was sufficient (in most circuits) to reduce the voltage measurement error, caused by connection of the meter, to an acceptable level

hope this is what u r looki for and hope this helps u....

Answer 2

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