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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
Will you produce a 3 phase voltage if you rotate a 3 phase motor physically at its specified rpm?
yes
How can input impedance is made purely capacitive or inductive or zero or infinite?
By using a matching network, or filter (active or passive).
To find the resistance in a circuit, use the equation R = V/I, where R is the resistence in ohms, V is the voltage, and I is the current in amps. Therefore, your equation is R = 120/0.6. Therefore, the resistance is 200 ohms.
Hope this helps
What is US voltage and Ecuador voltage?
US Voltage is 120 V @ 60 Hz.
Ecuador Voltage is 120 V @ 60 Hz.
They're compatible, the plugs are also the same.
What is the reason for a positive ground system?
Modern vehicle ignition systems use a negative ground system.
The reason some older vehicles used a positive ground system was because their manufacturers did not realize that metal erosion caused by sparking causes the center electrodes of the engine's spark plugs to be eaten away by the sparks if that electrode is connected to the negative side of the ignition coil's high tension output.
Such erosion can quickly make the spark-gap too large, causing late ignition problems which can seriously reduce the power output of the engine.
So, when using a positive ground system: a) the spark plugs had to have their spark-gaps adjusted every one or two thousand miles and b) the lifetime of the plugs was only around 5,000 miles or less.
Explanation
It is a fact of physics that, after millions of sparks, due to metal erosion there will be less metal on the electrode that is connected to the negative side of a dc (direct current) ignition coil.
So the center electrode of a spark plug will not erode away due to sparking if it is connected to the positive side of the ignition coil's high tension circuit and will erode away if is connected to the negative side.
As the spark plug's outer casing is much larger in area than its center electrode, if it is connected to the negative side of the ignition coil's high tension output, the erosion of the outer casing caused by sparking is hardly noticeable and this fact has the additional benefit that the spark-gaps of the plugs hardly ever need to be adjusted during their lifetime which, nowadays, can be well over 20,000 miles.
Relationship between field current speed and induced voltage in excited dc generator?
The equation is
Ea = PNw(phi)/(pi) (see formated at http://www.sitmo.com/gg/latex/latex2png.2.php?z=100&eq=E_a%3D\frac{PNw\phi}{\pi})
where Ea is the induced voltage, P the number of poles of the machine, w the electric frequency in rad/s, (phi) the magnetic flux.
referecen:
A. E. Fitzgerald et. al. Electric Machinery, 6th edition. McGraw-Hill.
Circuit of soft switching technique using zvzct in buck converter?
yes, zvzct is used to reduce the power dissipation and improve the efficiency of the circuit
How can you get the largest voltage difference?
There is no such thing as a 'voltage difference'! 'Voltage' means 'potential difference', so what you appear to be asking is "How do you get the largest potential difference difference?'!
Potential difference is caused by the separation of charges between two points. The greater the amount of charge separation, the greater the potential difference.
Does the Prius use regenerative breaking?
Yes.
Energy generated during regenerative braking recharges the traction battery and is later used to power the car.
The Prius also has friction brakes (disk/drum), which are used at very low speeds or for hard braking.
And it's braking, not breaking.
What are the advantages of series circuit?
The advantage of series is it uses less current than parallel
A lot of points are factored when a utility decides to choose 50 or 60 hertz, sometimes it may even been a political rather than a technical one. We have seen various types of wars on measurements types of units used or have been an interested but an innocent invitee in format wars in electronics like 8 track v/s cassette, v2000 (an excellent system) V/s the betamax (also with some notable features) and the vhs. Now we are also extended into the video disc formats. However if we were to look closely many of us will agree that 60hz is a good choice. All inductors and motors could be smaller, and the benefits will encompass a wide array of electrical and electronic goods to which the changes will almost be transparent. But it should be noted that most critical and large capital intensive plants and machinery, including certain medical equipment, will not take too kindly to such a change, which, besides straying from the critical specs, or worse still may give up altogether, unless expensive time consuming replacement or an equally complicated and efficient cycle converter is installed before the system is connected to the mains.
As a historical note, 60Hz was originally chosen in the US to help market AC power systems to customers. The ploy was that a clock could run using a synchronous AC motor and at 60Hz, the gear mechanism would be greatly simplified. Then the job of keeping accurate time fell to the electricity company by maintaining a constant frequency. Prior to this, many different frequencies had been tried.
As regards 50 Hz in India it is descendant of the British Imperial system. Technically speaking operating 50 Hz versus 60 Hz would not make much difference but, to achieve it, either the prime movers - for example steam turbines, gas turbines and diesel engines - would need to be able to tolerate a 20% increase in speed or the alternators they drive - which produce the electricity - would need to be completely rebuilt with extra poles and windings so that they could continue to run at the same rotational speed. The costs of doing such re-engineering would be enormous and could not be justified as "economically worthwhile" from the point of view of actual necessity, quite apart from the severe problems which would be caused to assuring operational continuity of service whilst such changes were made.
Further, for any load equipment - machines, appliances, etc. - that have reactive components (capacitors/inductors), the effects of a frequency change from 50 Hz to 60 Hz on such impedances would not be trivial and would significantly alter their in-circuit behaviour. This means changes would have to be made to the sizes all such reactive components to achieve the same effects at the higher frequency. Doing that would be yet another enormous cost of conversion from 50 Hz to 60 Hz which could not be justified as economically worthwhile.
KVA is a measurement of power; kV is a measurement of voltage. You're asking "What is the power for voltage?", which makes no sense. Power = Voltage times current.
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This test provides data for determining the regulation, efficiency and heating under load conditions and is employed only when two similar transformersare available. One transformer is loaded on the other and both are connected to the supply. The power taken from the supply is necessary for supplying the losses of both transformers and the negligibly small loss in the control circuit. The primaries of the two transformers are connected in parallel across the same a.c supply. With the switch open, the wattmeter reads the core loss for the two transformers. The secondaries are so connected that their potentials are in opposition to each other.
It depends on the periodic time of the supply which, in turn, is determined by the supply frequency. So, work out the periodic time of a 50 or 60-Hz waveform, and go from there.
If current is 3 amperes and resistance is 1.5 ohms, then voltage is 4.5 volts. (Ohm's law: voltage equals amperes times resistance) Power is volts times amperes, or 13.5 watts. A watt is a joule per second, so suppling 13.5 watts for 4.5 seconds produces 60.75 joules.
What is Coefficient of coupling?
It is a measure of how close is a coupling between two coils it gives an idea of wat portion of the flux produced by one coil links with the other coil
If there is less voltage across a resistor, there will also be less current.
As for the second question, I assume you mean two resistors in series. If the voltage or potential difference across one decreases, then the other one must increase, due to Kirchhof's Voltage Law: the total voltage across the two resistors must be equal to the voltage across the battery, which is usually assumed to be constant.
AnswerYou can think of voltage drops in terms of a water radiator central heating system. In order to drive water around all the radiators, there must be a difference in pressure across the entire system. But for water to flow through each, individual, radiator, there must also be a difference in pressure across its input and output orifices. The sum of these individual pressure difference must equal the pressure difference across the entire system.
If you now equate a pressure difference across an individual radiator with the voltage drop across a resistor, then the sum of the voltage drops across each resistor must equal the voltage across the entire circuit.
You should also realise that voltage does not 'slow down' current -it affects its magnitude (in amperes)
From copper and manganin which has higher resistance?
The question is actually wrong, they can both have the same resistance if configured differently, the real question should be which has a higher resistivity which is the electrical resistance found in a standard amount of each material. In this case Manganin has a higher resistivity than copper.
What is the application of a B-H curve?
A saturation (B-H) curve, shows the limitations that a magnetic field can reach in a given material's cross-section or area. Larger fields require more area and volume.
Ferromagnetic-cores are examples of how this sets a minimum limit on the size of a motor, generator, or transformer.
