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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
Power plant based objective type question answer?
objectives of the power engineer in a plant is to monitor that the plant is operating efficiently and and repairing as necessary
What types of motors are used in escalator?
slip ring induction moters is used due to its high starting torq
Difference between 89s51 and 89c51?
Difference Between the 89C51 Micro-controllers and 89S51
Following are the main differences between 89S51/S52 and 89C51/C52
- In S series the main difference is that you can program the "S" verison through ISP (in application) or using very simple programmers, while the "C" version still needs "full" parallel programmer . Where ISP stands for In System Programming
- 89s51 has more new feature than 89c51 such as Watchdog Timer
- s 51 is more cheaper than c 51 . if you want to use the application for longtime better use c 51 .
History of diesel power plant?
in 1913, Rudolph Diesel proposed a new type of internal combustion engine that had more pressure. This raised the temperature of the gas in the cylinder. This, then, allowed a lower grade of fuel to be used instead of highly combustible gasoline.
In parallel circuit the current through the resistors are different in values depending upon the values of resistors. But the sum of the currents across all the resistors will be equal to the current through the sourcgsvg bdjasuhafyuhda
What is the meaning of electricity cutoff?
An electricity cutoff is when the electricity is turned off. Different than a power outage, this usually occurs when someone does not pay their bill on time.
What is a sinusoidal AC waveform?
Its actually a sine function graph. It illustrates the variation of voltage and current with time. Yeah voltage varies every second in your house, only reason you cant detect it is the high frequency( >60 hz) at which they are transmitted.
Efficiency is measured as the ratio of power output to power input. In this case the power input of the generator is 240V * 25A = 6000 VA however the stated losses are 900 W so the power output is 6000 - 900 = 5100W. Then the efficiency would be 5100/6000 = 0.85 or 85% efficient.
If temperature increases than the resistance increase or decreases?
If temperature increases the resistance will also increase. This is why a light bulb is a non ohmic conductor. As the light bulb filament gets hotter its resistance will increase.
Additional Comments
It depends upon the material involved. In general, for pure metal conductors an increase in temperature will cause their resistance to increase. For insulators, an increase in temperature will cause their resistance to decrease -which is why excessive temperature is often the main reason why insulation fails. Alloys can be manufactured that will maintain a relatively constant resistance over a wide range of temperatures.
Temperature affects resistance indirectly. What is actually being affected is the material's resistivity. Resistivity is one of the factors that determines resistance.
The resistance of any given material can be calculated over wide range of temperatures, using the temperature coefficient of resistance for that material.
Full-form Of MMF: MAGNETO MOTIVE FORCE
Definition Of MMF ( Magneto motive Force ): Just as electromotive force ( emf ) is necessary to pass current in electric circuit, magneto motive force ( mmf ) is necessary to establish flux in the magnetic circuit. Magneto motive force is the multiplication of current flowing through the coil and the number of turns of the coil.
Unit of magneto motive force ( mmf ) is ampere turn.
Thus, it should be understood that the magneto motive force can be increased by increasing the number of turns in the coil or by increasing the current flowing through the coil or by increasing both.
CommentThe unit of measurement of magnetomotive force is actually the ampere, although it is frequently spoken as 'ampere turn' to prevent its confusion with electric current.
First of all, the overhead lines are cheaper because they are bare, while underground cables are armoured and insulated, hence explaining the higher price. Overhead cables come of course with accessories like poles and insulators (mostly porcelain). For shorter distance, underground cables are preferred as the cost of pole erection does not exist.
It's also worth pointing out that the cost of excavating a trench is more expensive than erecting an overhead line, and this cost escalates dramatically with higher voltage systems. For example, a 132-kV double-circuit underground line is between 5 and 8 times the cost of an overhead tower line, whereas an 11-kV single-circuit underground line is up to twice the cost of a wooden-pole overhead line.
Another name for cycle per second is?
The metric unit of frequency is the hertz (Hz), which is one cycle per second. It is named for German physicist Heinrich Rudolf Hertz (1857-1894).
Why do you not use silver for conducting electricity?
For electrical conductivity silver has not much advantage copper is much cheaper. The electrical conductivity advantage for silver is in the ratio 63.0 to 59.6.
Silver 18.50 USD/oz
Copper 3.8 USD/lb
Note the different units for the comparison.
Different kinds of splices and joints?
The four types of splices and joints are the Western Union splice, tap splice or tap joint, fixture splices or fixture joints, and rattail joint. The most common among the four wire splices is the Western Union splice.
Starting current of 160 kw motor with star delta starting?
Assuming the Motor is IE1 Efficiency and 4 Poles, the in rush current will be 1183 A
What is the total kWh of electricity generated in US?
4 159 514 Giga watt Hours annually (X1000 = MWH x1000 again =KWH) or 475GWH aveage daily output Interestingly if you wanted to generate this amount of power using solar thermal power stations at todays prices, it would cost $4.75 Trillion dollars! This sounds like an awful lot until you look at the Iraq War which has so far cost $3 trillion. So if the budget for Iraq had been invested in Solar, there would be at least 63% of US electricity coming from the sun, but probably more with economies of scale and technological improvements.
What is the amperage of the European electrical power systems versus that of North America?
In Europe, 230 V is the normal domestic supply whereas in the US it is 120 V. For an appliance of a certain power rating, the current taken will be inversely related to the voltage, by Ohm's Law, ie power = volts x amps. So the current at 230 V will be in the ratio 120/230 of that taken at 120 V
You get more voltage with higher speed and more amperage with more turns of wire.
Also by adding more coils of wire carrying current around the iron core
Motors and generators.
Motors may be electrically powered or spring powered. When steam or fuel powered they are usually referred to as engines.
Generators may be motor or engine driven, water driven or wind driven, and even animal driven.
Waterwheels, turbines and windmills would also be rotating machines.
There are rotating machines that cycle over and back, as opposed to a continuous rotation; an example is the rotary solenoid.
What is a flange isolation kit?
It's a gasket and non-conducting bolts/nuts that join two pipes and prevent electric current from passing between them. It's typically used to prevent corrosion.
Previously when transmitters were configured for 0-20mA signal it was very difficult to identify an open circuit at 0mA,hence to supersede this defect it was decided to configure the transmitter as 4-20mA signal,so that if there is open signal it can be easily identified.
What is one and half breaker system in electrical lines?
One and half breaker system is an improvement on the double breaker system to effect saving in the number of circuit breakers. For every 2 circuits, 1 spare breaker is provided: Two feeders are fed from two buses via their associated circuit breakers and these two feeders are coupled by a third circuit breaker which is called tie breaker. During failure of any of the two feeder breakers, the power is fed via the breaker of the second feeder and main breaker (tie breaker).
Define Velocity of propagation for co-axial cable?
The velocity factor is the speed at which an RF signal travels through a material compared to the speed the same signal travels through a vacuum. The velocity of propagation is inversely proportional to the dielectric constant. Lowering the constant increases the velocity.
Generally, the higher the velocity factor, the lower the loss through a coaxial cable.
General Rules for Coaxial Cable
D = diameter of insulation under the shield
d = diameter of inner conductor.
Velocity Factor, Velocity of Propagation, Vp
The higher the velocity factor, the lower the loss through the cable.
Raising the D/d has no effect on Vp
Raising the dielectric constant lowers Vp
Capacitance
Raising the D/d ratio lowers capacitance
Raising the dielectric constant raises capacitance
Impedance Raising the D/d radio raises impedance
Raising the dielectric constant lowers impedance
Attenuation or Loss
Raising the D/d ratio lowers attenuation
Raising the dielectric constant raises attenuation
So in simpler terms the larger amount of dielectric between the center conductor and sheath equals less loss in RF. Trunk cables have less loss than feeder legs.
What are the kinds of electric charge?
The kinds of electric charge are positive charge and negative charge
