Electrical Engineering

There is really no advantage, the only purpose of having the variety is for motor manufacturer companies to be able to sell their product to customers if the building's electrical service is of a Delta of Wye configuration.

10MW is equal to 10,000,000 watts or 13,404 HP

Explain how energy losses can be minimised when converting it into forms for use by consumers:

Transformers help. Step-up Transformers convert a low voltage and a high current. The low current loses less energy over long distances. A step-down Transformer does the opposite and can likely be found somewhere down the street from you (in America they are the large green boxes that you are told never to touch).

Electricity is supplied to consumers through the National Grid at a very high voltage to reduce energy losses during transmission. Transformers are used to increase or decrease the voltage of the supply. Electricity is charged in units. One unit is equivalent to one kilowatt of electricity used for one hour.

Power stations are built in order to generate electricity.

There are four main stages:

*the fuel is burned to boil water to make steam.

*the steam makes a turbine spin.

*the spinning turbine turns a generator which produces electricity.

*the electricity goes to the transformers to produce the correct voltage.

The energy needed to boil the water comes from fossil fuels or nuclear fuels. Renewable energy resources such as wind and wave power may drive the generators directly.

The National Grid:

Electricity is transferred from power stations to consumers through the wires and cables of the National Grid. When a current flows through a wire some energy is lost as heat. The higher the current, the more heat is lost. To reduce these loses, the National Grid transmits electricity at a low current. This needs a high voltage.

Power stations produce electricity at 25,000V. Electricity is sent through the National Grid cables at 400,000V, 275,000V and 132,000V.

Step-up transformers are used at power stations to produce the very high voltages needed to transmit electicity through the National Grid power lines. These high voltages are too dangerous to use in the home, so step-down transformers are used locally to reduce the voltage to safe levels. The voltage of household electricity is about 230V.

energy transferred (kWh) = power (kW) x time (h)

Simply put, an electronic device that stores charge is a capacitor.

50 ohms...!

A multimeter is used to measure various parameters in an electrical circuit. It can be used to measure things like voltage, current, resistance, frequency, and more depending on the how advanced the meter is.

The digital aspect of the meter is easier to explain with respect to an analog meter. The old analog meters used built in analog circuits to detect the above parameters and display the measurement by moving a mechanical needle a certain distance based on the magnitude of the measurement. This distance could be correlated with the magnitude using formulae and a scale was printed on the face of the meter so you could tell what value the needle was pointing at.

Digital meters, however, take the analog signals and convert them to digital signals. These digital signals represent binary information that a micro-processor can read. The processor can be programmed to interpret the incoming data and then display in on the screen.

by noticing the polarity of theohmmeter a diode can be checked for continuity and blocking ability However it will not tell you how good or bad the device itself is

BY keeping the multimeter in diode mode and keeping properly the positive and negative terminals of the multimeter. If the diode is good multimeter will show a reading of 0.5 else there will be a short.

Because that is what a capacitor does, resist a change in voltage. It holds a certain amount of energy per charge (voltage), and to change that voltage requires current proportionally to the capacitance.

In an Induction motor synchronous speed is inversely proportion to No. of poles if we increase No. of poles speed will decrease they are derived through formula as under

P= 120*f/Ns

Where P= No. of Poles

f= Rated frequency

Ns= Synchronous speed of flux.

Simply put, the purpose of a resistor is to 'resist' the flow of current. Ohm's Law tells us that for a given voltage, the larger the resistance, or value of that resistor, the lower the current that will flow. Ohm's Law states that I (current) = E (voltage) / R (resistance)

- where current is measured in amps, voltage is measured in volts and resistance is measured in ohms.

A phase - Brown

B phase - purple

C phase - Yellow

Neutral - Gray

Note: Phase B of high leg delta must be colored in orange or tagged. In utility meter the high leg shall terminated in Phase C. This apply only in utility meters.

volt drop and potential difference are effectively the same thing, although the term volt drop is usually used in reference of what voltage has to occur for a diode to conduct, or what volt drop is expected across a long wire etc, potential difference is used to refer to the difference in voltage over a potential divider.

Yes

Your original question was in two parts:
1.) How many ohms in an open circuit? Infinite ohms (the meter will show no measurement).
2.) How many ohms in a short circuit? 0 ohms. There would be no measurable ohms as there would be no resistance in the altered circuit.

You are presumably referring to an 'R-L-C' circuit. At resonance, the load current is in phase with the supply voltage and, so, the power factor is unity.

This depends on the duty of the square wave - if it is 50%, then it will be 1/2 the peak. If it is 33.3%, then it will be 1/3 the peak.

One horsepower is equal to 746 watts.

You use a transducer in a wheatstone bridge. The wheatstone bridge allows you to find an unknown resistance.

The terms a.c. and d.c. stand for alternating current and direct current, respectively.

http://www.allaboutcircuits.com/vol_1/chpt_16/2.html

just read it once every thing will b clrd in your mind

1) (ex: for 360 degree--->10 cm on the paper).

2) Draw simple sinusoidale wave.

3) This wave has a period of 2*pi in rad or 360 in degree (it's a multiple of 2*pi in fact).

4) The next wave will be 120 degree distant from the first wave.

5) So you move 120 degree (or 10/3 cm) from the first starting point (having amplitude=0) of the first wave.

6) Draw the starting point (having amplitude=0) of the second wave at the distance mentioned in 5).

7) Then starting from the point in 6) draw the second wave similar to the first wave.

8) Same procedure for drawing the third wave (repeate procedure 4 till 7 but switch the first wave with the second and the second with the third).

9) The formulas are:

10) In fact when x=pi/2-----------> VL1=Vp=|Vmax|

x=pi/2 +2pi/3--> VL2=Vp=|Vmax|

2 basic types, Gas shielding, and flux shielding. Gas shielding comes from compressed tanks of inert gas such as argon. these gases are pumped through the welding hose and over the weld pool. The flux type protects the weld by covering it in a layer of slag that prevent it from being contaminated by the surrounding air.