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Electrical Wiring
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What is the amperage of a 20 HP 240v single phase motor?
Typically single phase motors go up to 10hp. Wouldn't be very efficient at about 100 amps. A 20hp 3 phase motor at 230v pulls 52 amps. The 10hp single phase 230v pulls 50 amps.
How do you convert kva to kw and currents?
3 phase kVA = V*I*sqrt(3)
Where voltage is line to line, and current is the actual RMS current flowing in the a wire.
kW = V*I*sqrt(3)*Cos (phi), where phi is the angle between the voltage and current; Cos (phi) is also known as the power factor. kVA is the vector sum of kW (real power) and kVAR (reactive power).
As the equations above suggest, you must know the voltage to correctly calculate the current.
Phase difference is 120 degrees because that is one third of 360 degrees.
In a multi phase power system, you want each phase to divide a full cycle evenly. So, in a three phase system, each phase is delayed by one third of a cycle.
A full cycle at 60 Hz is 16.7 mS, or 360 degrees. One third of that is 5.6 mS, or 120 degrees.
A full cycle at 50 Hz is 20 mS, or 360 degrees. One third of that is 6.7 mS, or 120 degrees.
It works normally. Well actually there are 380 volts across two lines of a 3 phase AC source, so it should work normally.
It stands for watt-hour. In relationship to batteries, it measures how many watts in an hour a battery can sustain. A 63 watt-hour battery will supply 63 watts for 1 hour, or 6.3 watts for 10 hours or 31.5 watts for 2 hours, etc. It is extremely difficult to determine, from this number, how long your equipment (say, a laptop) will run using a 63 hour battery. The thing for which this number is most useful is battery comparison. A 20 WHr battery will last twice as long as a 10 WHr battery and half as long as a 40 WHr battery and so on.
What wire gauge used for headphones?
The wire gauge in thin headphone cables is quite small. I have read of people rewiring their headphones using 12 Gauge wire. There are commercial cables that use 11 gauge. The thicker the wire the less the resistance up to a point. Many headphones use 22 or 24 gauge and it seems to work OK.
What is the first hotel that had electricity?
In 1881, Prospect House on the shore of Blue Mountain Lake in New York's Adirondack Mountains was the first hotel in the world with an electric light in every room.
As it was far out in the wilderness Prospect House had its own Edison dynamo to generate that electricity.
The hotel was gone in 1915.
To answer your question properly, a few explanations of atomic structure are in order first. An atom is made up of three main subatomic particles; a proton, a neutron, and an electron. The only exception to this rule is Hydrogen, but this is irrelevant for this discussion.
Inside of the atom is the nucleus, which contains the protons and neutrons. Neutrons carry no net electrical charge; hence they are neutral. Protons contain a positive (+) electrical charge. Finally, the electrons circle the outside of the nucleus and contain a negative (-) electrical charge. Though it is not really correct, an easy model to visualize this is to think of our sun as the nucleus and the 9 planets as electrons.
As the old saying goes, "opposites attract." This means that electrons are attracted to protons, protons are attracted to electrons, and neutrons are attracted to neither. Following this logic, electrons repel other electrons and protons repel other protons. This constant attraction and repulsion between the particles keeps an atom together.
Now, to answer your question of what causes electricity, simply put, it is electrons. There are two different types of electricity; static and dynamic. Static electricity is what we're all familiar with on a cold, dry day when we go to turn on a light switch and get zapped. The reason this happens is that there is a build up of electrons on our bodies due to the dry conditions. These electrons simply join other atoms and become "overcrowded." When we touch metal, they are rapidly released from our body in the form of a spark.
Dynamic electricity refers to all other forms that we're used to, such as what's running your computer, T.V., automobile, and cell phone. In this case, electrons actually "move" through the wires. The reason they move is similar to the reason why a ball roles down a hill. There is a difference in "heights" at each end of the wire, only in electrical terms, this is called a difference in "potential."
Think of what a battery is. There is a positive end and a negative end. But they are stationary on the battery and can never touch. However, if the two ends are connected by using a wire, electrons will have the ability to flow from negative to positive. Remember, opposites attract. What you see in the form of electricity, then, is simply the energy given up by electrons flowing through a wire because they are being attracted by protons. What happens if all of the electrons match up with all of the protons on the other side of the battery? The battery is dead.
How much electricity does it take to make 1 sheet of paper?
A sheet of paper is about 4.5 g, which is 0.0000045 tonnes. It takes about 10,000,000,000 J of electricity per tonne to make paper, so about 45000 J per sheet, which is the same as 0.012 kWh.
Recycled paper takes about 40%-64% less electricity to make.
How do you megger the windings of a single phase motor?
Using a megger you check from either positive or nuetral to ground. The megger should read open (usually OL). It doesnt matter which connection you choose as long as one is ground. If the megger shows anything other than open the windings are bad.
Why do you balance single phase loads across a 3-phase supply system?
On a Delta 3-phase you connect the single phase loads between pairs of the 3-phases. Warning both sides of these loads will be hot! You may want to use 3 isolation transformers so that the real loads have a neutral line.
On Y 3-phase you connect the single phase loads between one of the 3-phases and neutral.
In each case to balance the loads, try to put similar loads on each phase (or pair of phases).
What does an electric current continually seek a pathway to?
An electrical current continually seeks a pathway to ground.
What causes an electric humming sound in equipment?
The sounds are caused by the oscillations of the frequency changing from positive to negative when voltage is applied to electrical equipment.
See related links below.
What will cause noisy operation of a motor?
Noisy operation of a motor is usually caused by the motor's bearings. Use an instrument that can check the temperature of the bearings. If they are hotter than the surrounding temperature of the motor's frame then change them out for new ones. New bearings should quiet the motor.
What size circuit breaker should be used if you use 5 horsepower of air-conditioning?
To answer this question a voltage value must be given. Circuit breakers protect the conductors that feed the load. The lower the voltage value, the higher the current value, hence a larger the wire size is needed and therefore larger the breaker size for the circuit.
In reverse the higher the voltage value, the lower the current value, hence a smaller the wire size can be used therefore smaller the breaker size for the circuit.
The two are unrelated. Volts is the measurement for Electrictiy. Hertz is a measurement for a transmitted radio wave.
How many volts should a capacitor read if working properly?
Capacitors do not generate voltage by themselves. The voltage you read across the cap will simply be whatever voltage the external circuit puts into it. The answer depends, then, on the particular circuit, so there is no real answer to your question. It's like asking how much water is in a properly functioning bucket. The answer (which doesn't really help), is 'however much you put into it'...
I = E/R
What is the difference of earth and insulated return in an electrical system?
An earthing system is a system where circuits are connected by a ground. An insulated return system is how power is transferred to trains.
How do you tell how many poles a 3 phase 480 volt motor has?
It is based on the RPM of the motor. Use the following formulas for 50 and 60 Hertz. The mathematical formula is Frequency in Hertz times 60 (for seconds in a minute) times two (for the positive and negative pulses in the cycle) divided by the number of poles. For 60 hertz, the formula would be, 60 x 60 x 2 = 7,200 no load RPM divided by the number of poles will give you the nameplate RPM of the motor. eg from above formula 7200/2 pole = 3600 RPM, 7200/4 = 1800 RPM, 7200/6 = 1200 RPM
What appliances can you find a LM317 Chip in?
LM317 is a variable-output voltage regulator. I would expect to find it in small home appliances with electronic controls, portable radios, car electronics, cell phone chargers, etc.
If you need to find the chip somewhere to do some repairs, you can probably ask a manufacturer to send you a (free) sample. Otherwise, you can buy small quantities online from places like digi-key.
What is the basic function of a megger?
On the whole megger testing is non destructive. What happens is a DC voltage is applied to the device or winding under test. It is an insulation test to see is the insulation has been injured in any way to cause a short circuit when normal power is applied to it. On my megger there are 3 ranges 300V, 750V, and 1000 volts. Applying the proper voltage is essential to not damaging the device you are testing. Working voltages up to 240 volts should use the 300 range. Working voltages up to 600 volts use the 750 volt range and working voltages above 600 use the 1000 volt range. As you can see if you used the 1000 volt range on a device that had a working voltage of say 24 volts you could damage the insulation just by testing it. So meggering a device is non destructive if you use the tester as its instructions tell you to.
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For the sort of standard text-book stuff being asked in this question it's much better to use the excellent Answers.com and other well-known "reference" or "encyclopedia" sites. You will also see very useful photos and diagrams to help to explain the answer.
The actual answers on WikiAnswers must currently be text-only and, for other information such as pictures, photographs, etc., separate links must be added below the answer.
For instance, the Related Link to Answers.com's site - shown below the Related Questions for this answer - shows a circuit diagram, as well as a good description, of a "megger" instrument.
WikiAnswers is not ideal for use as a "reference site" or an "encyclopedia site" because you have to wait until someone either writes a special answer to your new question or merges it into an existing question asking about the same thing.
WikiAnswers is part of the Answers.comTM network.
What is Full load college course?
A full-time load is considered to be enrolling for at least 12 credits (semester hours), or more. The average course load is approximately five course on the average of 15 credits per semester. However, it depends on the specific program of study and its curriculum layout. Anything less than 12 credits is considered part-time.
A full-time load is considered to be enrolling for at least 12 credits (semester hours), or more. The average course load is approximately five course on the average of 15 credits per semester. However, it depends on the specific program of study and its curriculum layout. Anything less than 12 credits is considered part-time.
A full-time load is considered to be enrolling for at least 12 credits (semester hours), or more. The average course load is approximately five course on the average of 15 credits per semester. However, it depends on the specific program of study and its curriculum layout. Anything less than 12 credits is considered part-time.
A full-time load is considered to be enrolling for at least 12 credits (semester hours), or more. The average course load is approximately five course on the average of 15 credits per semester. However, it depends on the specific program of study and its curriculum layout. Anything less than 12 credits is considered part-time.
A full-time load is considered to be enrolling for at least 12 credits (semester hours), or more. The average course load is approximately five course on the average of 15 credits per semester. However, it depends on the specific program of study and its curriculum layout. Anything less than 12 credits is considered part-time.
A full-time load is considered to be enrolling for at least 12 credits (semester hours), or more. The average course load is approximately five course on the average of 15 credits per semester. However, it depends on the specific program of study and its curriculum layout. Anything less than 12 credits is considered part-time.
Why capacitors may pose an electric shock even in unpowered circuits?
Capacitors are used to store electricity in a circuit, so even when the circuit is unpowered, so long as it's still functional, it would still give off a small electric shock due to electric charge present in capacitor.
What are the uses of three phase transformer over single phase and their losses?
For a given load, a three-phase system requires around 75% of the volume of copper required by a corresponding single-phase system and, so, is more economical. A three-phase supply also delivers power more or less continuously, whereas a single-phase supply delivers power in pulses. Finally, three-phase motors are self-starting and physically smaller than single-phase machines of the same power rating.
