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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
How would you measure power factor of the balanced three phase load by two wattmeter method?
Yes. The wattmeter's current coil will have to be connected into one of the line conductors, and its voltage coil between that same line conductor and the neutral point of the load.
Connected this way, the wattmeter's voltage coil is measuring one of the three phase voltages (line-to-neutral voltage) while its current coil is measuring the corresponding phase current (for a 4-wire system, the phase current = line current). The power factor (cosine of the phase angle) is accounted for automatically within the wattmeter.
So the wattmeter will measure the true power (in watts) of one phase.
The total power, therefore, will be 3x the wattmeter reading -providing, of course, that the load is balanced (i.e. each phase is identical). WebRep
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What is a Van de Graff generator?
The Van de Graff generator was named after Van de Graff, who invented it.
A Van de Graff generator is a device used to store an enormous amount of electric charge (either positive or negative) on a metallic sphere so that a very strong electric field can be produced. This strong electric field can be used to accelerate charged particles like protons, alpha particles etc.
In the Van de Graff generator, charges from an electric battery are separated and stored on a metallic sphere which is mounted on an insulating pillar.
How many amps does a 3 phase 10 hp motor draw when running at 380 volts?
A three-phase motor is supplied by three 'hot' conductors, called 'line conductors'. The voltage between any pair of these conductors is called a 'line voltage', and the current flowing through each one is called a 'line current'. The '10 A', you refer to in the question is a line current. In other words, it is the value of current flowing through each of the three line conductors. You cannot add them together, as they are independent currents.
So, the 10 A is not a 'total' nor can you add the three currents together to get 30 A. They are three, independent currents.
What components can be include in integrated circuits?
Except coils (inductance) all other active and passive devices could be included in an ic
What is a forward-reverse star delta?
A forward reverse star delta is a two in one motor starter where a motor first runs on star connection and then changed to delta connection after a time which has been set. The motor direction can be changed, whether forward or reverse
Why you need 250 ohm resistor in hart?
The resistor doesn't have to be 250 Ohms, anything from 100-600 will work equally well. The power supply is a low impedance to the hart signal shorting it out. Adding the resistor raises the impedance so that the signal can be detected by the calibrator. A small reactor would also work.
Ohms law states that a resistor must be present with current to receive a voltage (V=IR) this resistor converts current to voltage which is used as a digital voltage signal. (1-5 V).
The HART protocol uses 1200 baud Frequency Shift Keying (FSK) based on the Bell 202 standard to superimpose digital information on the conventional four to 2OmA analogue signal.
Hope this may help ful....
Sudhan.S
shansudhan@rediffmail.com
How does a speaker work in a circuit?
They will either pull in or push out depending on the polarity of the DC voltage and remain stationary.
This is a bad idea as the DC resistance of the voice coil is much less than the AC impedance of the voice coil and it is possible to overheat and burn out the voice coil due to the much higher current the DC voltage can produce in the voice coil compared to the AC voltage that would drive the voice coil in normal operation.
There are quite a few in Japan (the fastest going up to 581 km/h), there is also a test track at the Transrapid facility in Emsland Germany which designed and built a second system in China (Shanghai to Shanghai Airport).
I have also heard that a Transrapid system (UK Ultraspeed) has been planned, and is close to agreement by the British Government, that will link London, Birmingham, Manchester, Liverpool, Newcastle, Edinburgh and Glasgow (including several locations and airports in and around those cities).
There are also several systems planned for the U.S. and Japan.
What happens to the resistance of silicon as its temperature increases?
A: As temperature increases its resistance increases. Like all silicon diodes it will reach a point where the temperature coefficient is zero but it is at such elevated temperature to make it invaluable
What is the fractional horsepower motor?
I think you mean kW, not kwh. Fractional just means less than one.
How does the commutator reverse the current in a motor?
Commutator is a split ring which reverses the current .when the commutator turns around due to magnetic force and because of it even the current gets reversed
How much slip in a three phase synchronous motor?
Slip, 
, is defined as the difference between synchronous speed and operating speed, at the same frequency, expressed in rpm or in percent or ratio of synchronous speed. Thus
If your equipment is grounded using a separate ground wire, and the neutral wire breaks, the appliance may not function, but no one will be hurt.
If, on the other hand, you use the ground wire as the neutral, and it breaks, IF THE APPLIANCE HAS A METAL CHASSIS AND/OR CASING CONNECTED TO THE GROUND WIRE IT WILL BECOME LIVE!Anyone touching it could be killed!
It's just not worth saving a few dollars over. Buy and install the proper 4-conductor cable (called 3-wire with ground) and be safe.
A different take from a professional appliance installer and electrician:
Up until the mid to late 1980's the ground and neutral were tied to the same bar in the panel. So unless someone who has a house built prior to this has had a complete electrical service rebuild the ground and neutral of all of the circuits are connected to the same place.
If you have an older home and there are only three wires feeding a 220v appliance the ground and neutral are interchangable. In fact, if the unit had two hots, a neutral and a ground, the ground and neutral were tied together. This is still acceptable practice and is diagrammed in the specifications for every appliance appliance that I am aware of. (Only Miele for a time was particular about not mixing the ground and neutral, although they could never tell me why it mattered. They have since dropped that requirement).
There are a lot of new 220v appliances that have only three wires. Usually two hots and a ground. It would be perfectly fine to hook the ground to the neutral if that was all you had.
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As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances,
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
What would cause two fuses to blow on a electric motor starter?
the three phase induction motor will start run in single phase . through the remaining healthy phase, around 4.5 times normal current will flow through.Also rotor sbeed also decreases.
You can not keep the voltage constant while increasing or decreasing it!
CommentAn additional point worth making is 'voltage' doesn't 'flow'. By definition, it is the potential difference between two points.Why do the people sitting in the train does not get electric shock?
If the track is fed by overhead power lines then the track is the return path for the electric current and is at earth potential.That is 0 volts
In the UK we use a Third rail system which is raised up,and to one side of the rail.This rail is laid on china insulators and has a voltage of 750volt DC:- very dangerous since if you touch it it tends to clamp muscles on to it.
What happened if the DC voltage in the clamping circuit is replaced by an AC source?
we will get rectified voltage at the output.in case we replaced the DC source with AC source
Why induction motor speed is always less then synchronous speed?
induction motor never runs at synchronous speed, if it does so there would not be any relative speed between stator flux and rotor and no emf will induce in rotor and we can not apply motor principle as we need current carrying conductor in magnetic field.
It depends on the motor. You need to look at the specifications of the particular motor. In general, if there are only three conductors, not counting earth, then it is delta; if there are four, then it is star; if there are six, then it is star-delta and you need a star-delta starter.
What type of circuit is most common in household wiring?
The most common types of circuit breaker used are MCBs. (Miniature Circuit Breakers.)
The most common type of breaker used in most every residence in the U.S.A. is the non-adjustable trip breaker.
there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ampere, which states that it is "the constant current that will produce an attractive force of 2 × 10-7 newton per metre of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one metre apart in a vacuum.
the oldest man in the world being 3276.
