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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
1TR equals how much amps in single phase?
To answer this question a three phase voltage must be given. I = W/E.
What are the similarities and differences between direct current and alternating current?
Both alternating current (AC) and direct current (DC) describe the nature of the current in terms of its direction. DC describes when the flow of electric charge goes in a constant direction whereas AC describes when the flow of electric charge constantly reverses; in other words, the electrodes of the power source constantly switch between positive and negative.
How do you distinguish between conventional and non conventional energy?
Conventional current represents the flow from positive to negative; following the direction that independent positively-charged particles would travel. (N.B: equal charges repel, opposite charges attract.) Non-conventional current represents the flow in the opposite direction (from negative to positive) and is the direction in which electrons would flow.
Why induction motor is called asynchronous motor?
as we know that a rotating magnetic field is created by the satator current,and so in the rotor there is induced current and there by the rotor developes a unidirectional torque. so since the rotor runs with a speed other than the synchronous speed of rotating magnetic field produced by stator current so it is called as asynchronous motor..
asynchronous -means not moving with synchronous speed
--------------------mrityunjay
(kiit university .
b.tech 2nd year student)
Wind turbines have been around for 124 years.
It has been around from 1888 - 2012.
Texas and California are the leaders in wind generation in the United States.
What are the difficulties that can occur in working relationships and how can you resolve them?
Working relationships establish imaginary boundaries that are put in place by social expectation. Because society has a specific criteria for working relationships, there is a stigma against cultivating something that is more meaningful.
As we know numerical relays use DIGITAL SIGNAL PROCESSOR as its computational hardware and based on microprocessor.
WORKING:
Analog input is feed into the anti aliasing filter which is a low pass filter.Output of this filter is feed into the sample and hold circuit , frequency of sampling should be twice of our highest frequency of interest(according to the nyquist criterion).if sampling frequency kept low than aliasing input may occur.
after the sampling, signal are feed into the multiplexer,where all the signal get multiplexed and we have a single signal.this signal is feed into the analog to digital converter.this digital signal is feed into the microprocessor and microprocessor generates control signal according to its input.
for example
if you are using N.R. for over-current protection than you should set a value of current in your program.if the value of current passes through the circuit is greater than the set value..than N.R. enables the circuit breaker and hence our system is protected..
Can you get 480 volts from 220 volt 3 phase?
An object that throws off only 480 volts of electricity is no more powerful than a static electric shock from carpet in winter. Tasers can shoot out probes that are 20,000 volts or more.
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A voltage level of 480 volts is the working three phase service voltage of commercial and industrial sites in the United States. The service is usually a wye connection so that the star point voltage of 277 can be used for building lighting.
In Canada the three phase system voltage for commercial and industrial is 347/600 volts
How do you know if a transformer is a step up transformer?
You will most likely see a 'step-up' transformer on neon signs. The next time you're at a restaurant or bar, look at their neon sign. You'll see a black box (4" x 4" x 6"w) connected to the sign (usually). This is the transformer, and it takes 120 volts AC and steps it up to 7500 to 10,000 volts AC. This excites the neon gas and causes it to glow.
AnswerA step-up transformer transforms voltage to a higher level. Like 120 volts to 277 volts.
AnswerIt is type of transformer which is used to step up the voltage from low to high value in order to make it applicable for high rated appliances.
Not only for high rated appliances but also for transmission in power distribution systems. It is critical in this role. Power distribution systems depend heavily on step-up transformers to generate the high voltages needed for more efficient long-distance power distribution. (And yes, there are step-down transformers at the other end to make the voltages more "user friendly" and less dangerous.)
Why is star delta running used?
Star delta starting is used to reduce the dip in voltage which can feed back to the primary line which makes other customers unhappy when their lights dim each time a high HP motor is started on the same circuit they are connected to. By starting in a wye connection there is less disruption of voltage on the system that the motor is connected to, by starting the motor at a lower voltage and hence lower inrush current. Some utility companies will not allow across the line starting on motors above 30 HP.
This type of motor starting circuit is used less and less, now that VFDs and Soft Starters are becoming cheaper to purchase and more readily available in lower HP ratings
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What three things are needed to make a complete electrical circuit?
The first part is that you need a power source. The second thing is that you need a load. The third thing is that you need the power cables.
What happens when resistance is varied in a circuit?
A resistor will not change its value, unless the voltage exceeds the designed power capacity of the resistor. As the voltage increases, the current will increase, if the current gets too high it will cause the temperature of the resistor to increase, if the temperature exceeds the power rating of the resistor then the resistance WILL change. If it goes too High in temperature the resistor will open and current will no longer flow. A resistor is used to control current, and indirectly the .voltage depending on the application. Hope This helps. You must use Ohms Law to see the relationship.
What are performance characteristics of a transformer?
The properties of an 'ideal' transformer are (1) voltage ratio equals turns ration, (2) no losses.
What are the different types of splices for optical fibers?
1. Fusion splices: Use an arc to melt and connect two fibers.
2. Connectorised splices: Use various types of connectors like BNC, ST, etc. These can either be straight- or diagonal-cut fibers.
3. Epoxy splices: Here fibers are joined with the help of refractive index matching glue and guiding sleeves or jackets.
Why multimeter cannot used for measurement of insulation resistance?
Because ordinary ohmmeters are calibrated to measure a range of resistance values that are significantly lower than the resistance of insulation. It should also be realised that we usually test insulation resistance while subjecting the insulation to a high electric field, which a normal ohmmeter is incapable of producing.
How do you calculate transformer ampere per phase?
I assume you mean its 'rated amperes per line'? Manipulate the following equation to make I its subject:
Rated Apparent Power = 1.732 x VL IL
There is zero kilowatts in 1 volt.
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The formula for this sort of thing is Watts = Amps x Volts (WAVe). All else being equal, more amps means either fewer volts or more watts, more volts is similar, more watts means more amps or more volts, and fewer of the above produces opposite results.
It's like d = rt, or distance = rate X time. At 50 MPH for 1 1/2 hours, you have gone 75 miles. Faster, and you would have gone farther; slower would be shorter. Longer time would mean more distance, while less time is less distance. So the answer is...
If you bit an electrical outlet would it shock you?
Do not try this at home. Done it with a 9 v battery, that hurts.
My mother once stuck a bobby pin in an outlet when she was a child, the bobby pin EXPLODED and the shock she received was enough to cause a muscle spasm in her arm that threw her all the way to the opposite side of the room!
Never even think of touching an outlet with your tongue!
What is Ohm's law in a direct circuit?
Ohm's Law is a law of constant proportionality, and only applies to circuits in which the ratio of voltage to current is a constant over variations in applied voltage. Such circuits are called linear or ohmic circuits, and include most metals. However, in the case of metals such as tungsten, for electronic devices such as diodes, and for electrolytes, Ohm's Law does NOT apply, and we call such circuits 'non-linear' or 'non-ohmic'. For linear circuits, Ohm's Law simply states that the current flowing through that circuit is directly proportional to the voltage applied across its ends. The equation R = V/I is not, as many think, derived from Ohm's Law, but from the definition of the ohm.
How many KVA of genset to produce 10000watts?
A gen set will be rated for a certain kVA at a certain power factor, or certain kW at a certain power factor. If rated in kVA, the power factor indicates the amount of real power you will get (ie if rated at 10,000kVA at .95 pf, the gen set can generate .95 x 10,000kW, or 9,500kW).
The voltage for 4 bulbs in a circuit?
The circuit voltage or the resistance of the individual bulb is needed to answer this question.
Divide the total power (400 W) by the supply voltage.
What are the advantages and disadvantages of a gas circuit breaker?
The advantages of a circuit breaker are:
they are smaller in size than fuses
better versions may have electronic trips so they can adjust trip curve to suite circuit design
easier for end user to reset (no touching live parts)
no waiting to reset (as with fuses - spare must be found)
no cost associated with resetting unlike cost of replacement fuses
easier when ground fault protection is needed
The disadvantages of a circuit breaker are:
they are more expensive than fused switches
when a circuit breaker trips, you lose all power (with fuses you only lose that phase)
harder to coordinate fault selectivity
harder and more costly to obtain high short circuit interrupting capacities
What is application load balancing used for?
Load balancing, in programming, refers to the act of evenly distributing work among processors. If you want to write a program to take advantage of multiple processors, you should try to make sure each processor is doing the same amount of work as every other processor. If you don't, then one or more may finish well before the others, wasting processing time.
The magnetic loading and electrical loading is most important parameter in the electrical machine.
the electrical machine's torque is define as
T=winding factor*electrical loading*magnetic loading*rotor volume
You can see that the magnetic loading can decide electrical machines volume so this parameter is important.
A cable tray is a rigid structure to support electric cables.
