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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
Why moving iron or hot wire types meters can be used for measuring both AC and DC quantites?
Hot Wire
hot wire is a resistive device ir drop is the same regardless of frequency
hot wire can measure power true power regardless of frequency or phase angle
two wires for power current and voltage both to convert to a measured temperature integration speed depending on the mass of the wire(s)
hot wire can be a bimetal spiral connected directly to the pointer on the scale
Moving Iron:
the moving iron has a spring connected to an iron bar in a coil
dc or ac will cause the iron to be magnetized the amount of current will increase the deflection
normal 50hz 60hz and dc differences are very small
the iron will have induced eddy currents causing higher frequency to have less deflection 400hz on airplanes for lighter transformers... need a different calibration
see "Wigginton voltage tester" simplest moving iron i know of
one moving part, the iron
well 2 if you count the little compass on top to tell dc polarity
large solid core so different for 60Hz then dc by perhaps 10%
Basic construction of zener diode?
A zener diode has a heavily doped p-n junction allowing electrons to tunnel from the valence band of the p-type material to the conduction band of the n-type material, such that the reverse voltage is "clamped" to a known value, called the zener voltage.
Why transformer action takes place in a DC circuit?
A: A transformer is a PASSIVE ac component applying dc to it the wires resistance would be the only limiter for current flow. Usually a common transformer will burn up fast or slowly depends on power applied
What is a circuit with more than one path to flow?
All the branch circuits in your house are parallel. They have a constant voltage applied to any device plugged into an outlet. If you thought about an analogy for a parallel circuit, imagine that the rails on each side of rungs represented the hot and neutral wires of a typical household branch circuit. The rungs would be the loads connected in parallel. Each "load" draws the current needed to operate the specific device. The sum of all the currents for the "loads" is equal to the total current being supplied through the circuit.
Using Ohm's law what is the formula to find amperage in a circuit?
Take your circuit voltage and the power of the appliances and divide.E is voltage I is amperage and P is power or wattage. P=ExI Example. 3500 watt heater draws ? Amps on 220Volts I=P/E I= 3500w/220v I= 15.9Amps
In general, electrical circuits refer to the pathways or routes that are used to deliver electric power onto the power grid and out to the site where a customer actually uses it. It's possible to say the electric power grid is a large electrical circuit. It is. We can use terms like wire or lines or conductors when we talk about the power grid. You already know that there are transformers, circuit breakers (disconnects), fuses and other "stuff" in the circuits. An electrical circuit could be any subsystem of the larger whole. The electrical circuits in a residential structure could be all the wiring from the meter and breaker panel to all locations in the home. The electrical circuits of your home can be described this way. An electrical circuit could be a subsystem of a piece of equipment that helps an observer differentiate it from another subsystem. In a TV, for example, the video circuits are electrical circuits that are separate from the audio circuits. Each is a distince electrical circuit in this light, and someone like, say, a repair technician will be looking in the audio circuits to see why your TV has no sound rather than in the video section. The two electrical circuits are distinct in this light. We could go on, but this may cover the basics acceptably.
How is a regular light bulb different from an energy-saving light bulb?
By "regular" I think you mean a traditional filament (hot wire) bulb. That works by an electric current heating up the wire so that there is visible radiation from it. The problem with that is there is far more radiation (heat (ie infra red), even some ultraviolet) which the eye cannot see, so all that other energy is wasted. So-called energy saving bulbs rely on energy transitions within carefully selected atoms so that it can be arranged that most of the photons are in the visible part of the spectrum.
What are the components of a generator set?
Generator set, also known as genset, typically consists of components such as engine, alternator, control panel, fuel system, cooling system, exhaust system, battery and starting system, voltage regulator, control and protection devices, base frame and enclosure, etc. These components work together to generate electrical power and provide backup or primary power supply in different applications.
What is the difference between a simple circuit and a parallel circuit?
A parallel circuit is different in many ways from a series circuit:
1. In parallel, the voltage across all the devices connected is the same.
2. If a fault occurs in any device connected in parallel combo, then it has no effect on the operation of the other device.
3. In series circuit the current flowing through all the devices is the same while in case of the parallel one the voltage across all the devices is same.
How Do you Convert 15v DC to 5v DC?
There are several ways. the most simplest is by using a single rectifying diode that only lets current pass in one direction. This is called a half wave rectifying circuit. You only get half the power also.
The second is by a full wave, or bridge rectifier which consists of 4 rectifying diodes which can usually be bought as a single package with 4 pins which are identified for correct connection. This allows the alternating cycle current to pass alternatively to the output pins in a push-push mode and maintains most of the current flow that you put into it.
The result is a very jerky or spikey DC current usually higher than the rated AC voltage. To smooth the spikes, extra circuitry is needed such as capacitors and maybe some smoothing coils but is way too detailed and varied for printing here.
Type in your browser "Rectifier Circuits" and you will find a smorgasborg of results where some will give a more comprehensive explanation of how AC is converted to DC.
Regards
Who has the right of way when four cars stop at a four way intersection at the same time?
This does actually happen, no one should ever say things never happen, so when it does, cars traveling north and south go first, then cars driving east and west go next. If a driver is turning left, he or she must yield. Also its important to know that the person to your right has the "right" of way.
Can electricity flow in open circuit?
No
AnswerThe answer is YES! For example, if you connect a capacitor (which comprises two metal 'plates' separated by a dielectric or insulator), in series with an AC supply, then a continuous current will flow. If you connect the capacitor in series with a DC supply, then a current will flow for a short period, before the capacitor becomes fully charged.
Why the output voltage drop when the load current is increase?
As the load current increases the losses in the circuit increases (I2R loss) and speed of the generator decreases so the voltage falls a little. and this voltage fall can be adjusted by increasing the speed of the generator and Iron losses are taken as constant losses.
Why does one bulb make the others go out in a series circuit?
because current in parellel divides unlike in series if one fails all will fails
AnswerThe parallel circuit's load current doesn't 'divide'. It's the other way around! Each branch draws an individual current which then 'combine' to form the circuit's load current. However, the reason that the remaining lamps connected in parallel always work, even if one fails, is because each branch of a parallel circuit is subjected to a common supply voltage.
What is the relationship between capacitors in series and resistors in series?
resistor isdefined as the opposing the current flow in a circuit. capacitor is defined as the store the electric field in one forth of the cycle and the another quarter cycle stored energy will be released
The temperature of the sun's corona reaches at least one million degrees and possibly more. This is strange because the surface of the sun has temperatures of five thousand degrees. The corona is much farther away and logically should be cooler.
The total resistance is 5 ohms. Scroll down to related links and look at "Parallel Resistance Calculator".
Can 60hertz transformer use at 50hertz power?
As long as they're the same voltage, yes it will, but probably not for long. A lot depends on what type of appliance you're using. For instance, if it's an electric stove, you'd probably be OK, but if it has a clock, expect it to run slow. And even that too, dependfs on what type of electric stove it is. The problem is that at the lower frequency, the device has to draw more power in able to do the same amount of work that it would at 60 Hz. Because of that, some motors, electronically controlled devices and the like, tend to overheat as a result. For a window fan, it's probably no big problem (although I'd keep an eye on it until I knew for sure) but for something that's `frequency dependent', like a refrigerator compressor, I'd think you'd just be asking for problems. Usually during the day, voltages and frequency of the U.S. system varies in both frequency and voltage. A `brown-out' usually happens when the voltage falls below 80 volts, as compared to the nominal 117 volts. But too, so does the frequency. Tis is mainly because of industrial usage during the day, along with air conditioners and the like. Late at night though, it's usually closest to where it's supposed to be. Does it work? Will it work? Yes. The question is: For how long.
What is no load current in transformer?
I'm not sure that it is correct to say a transformer limits current under no load (maybe it is, depending on your application).
A step down transformer converts a high voltage at the primary to a lower voltage at the secondary. Under no load conditions, the secondary will be an open circuit. Since The primary current relative to the secondary current will be Np/Ns (the turns ratio, primary to secondary), and the primary voltage relative to the secondary is Ns/Np, the apparent resistance at the primary due to an open at the secondary will be (Np/Ns)^2*(open circuit). Since an open circuit is typically approximated as an infinite resistance, resistance is infinite. The turns ratio in this idealized example doesn't really matter, hence the transformer doesn't really matter (only the fact that a no load means an open secondary matters).
How can be three phase transformers connected in parallel?
It is common to pull parallel conductors to a transformer when the expected current is high enough. It can become difficult to pull 400A and larger wire so you can use 2,3 or 4 sets of smaller parallel wires to accomplish the current.
= =
Transformers are frequently connected in parallel with each other in order to increase the amount of apparent power (expressed in volt amperes) they can supply to a load.
What is meant by parasitic capacitor?
Parasitic capacitance is the unwanted capacitance between:
1. A signal line and other signal line.
2. A signal line and earth.
3. A signal line and power supply line.
Not that, I remember all (even most) of the effects, let me answer you with whatever I remember:
1. Unwanted coupling between two different signals, resulting in "crosstalk" between two signals. One signal interferes with other and other interferes with one.
2. attenuation / distortion of high frequency signals which have high impedance / limited current capability.
3. Ringing (unwanted oscillations) rising edge and falling edge of the signals rectangular / square wave.
Advantages of transistors over triode?
Transistors are sometimes referred to as semiconductor triodes.
OK, but to answer the question:
Vacuum-tube triodes need some hundreds of milliwatts to watts just to light the filament/heater. This is wasted power that can appear as waste heat in the circuit, and reduces the electrical efficiency of the vacuum-tube triode. Triodes also have limited lifetimes, commonly due to the filament/heater burning out, or losing its electron emission. Transistors have no such limitations and are (i) much more efficient, (ii) can run at much lower power, and (iii) have very long lifetimes.
Vaccuum-tube triodes cannot be made much smaller than around 10 mm/half an inch in diameter, and maybe the same length. Transistors can be made at the nanometre scale, so transistor electronics are much more compact. Imagine putting together a USB memory chip with (at least) 32,000,000,000 triodes!
Conventional triodes are able to operate to about 5 GHz (5000 MHz). Some special valves can work at higher frequencies, about around 100 GHz is the limit. Such valves are large, expensive, and have high noise figures. Low-noise, small, cheap transistors exist that can easily work past 100 HGz.
The emitter bypass capacitor, in a typical common emitter configuration, increases gain as a function of frequency, making a high pass filter. Removing the capacitor will remove the gain component due to frequency, and the amplifier will degrade to its DC characteristics.
Are the voltages across all branches of a parallel circuit the same?
In a parallel circuit, all the branches are joined together at their start and again at their end by a conductor (usually wire).
Now, the surface of a conductor (ideally) is an equipotential surface. That is, any point of its surface has the same electric potential.
And since the voltage across each branch equals the difference in electric potentials between its start and its end, and these potentials are the same for every branch, it follows that the voltages across each branch must be equal to each other.
