Electrical Wiring

Circut Breaker

Answer for USA, Canada and countries running a 60 Hz supply service. A neutral wire is usually white in colour. Answer for countries in Europe and other world areas running a 50 Hz supply service. It's blue in the UK on a domestic appliance 240V supply

The most typical three-phase voltage used in China is 380 V.

No longer than 46 feet. Longer than that switch to #12 on a 20 amp breaker.

Because copper is a very good conductor of electricity. Most other metals aren't as good, and would cause more resistance, resulting in the bus bar heating up.

Yes, there a difference between three phase and single phase electrical supply services.

It is not the "opposite" but the major alternative to parallel, which is a series circuit. In parallel circuits, each component has its own circuit path (input to output), while in series the components are connected to one another in a line.

A scheme for focusing sheet, beams by means of a periodic configuration of magnetic fields directed transverse to the beam is presented. Discussion of a particular model gives information about stability limits and perveance. This scheme, which lends itself to the incorporation of intense magnetic fields, should be immune to the space-charge instabilities of beams focused in longitudinal magnetic fields. The focusing mechanism is such as to produce coupling between the beam and electromagnetic waves of phase velocity exceeding the velocity of light. Application to millimetre-wave tubes is anticipated.

415V 3 phase is the line to line voltage. The line to neutral of this supply is 230V single phase. Therefore you use one of the phases and the neutral.

I assume your question relates to the need for a disconnect switch. To meet code you need a disconnect switch in the proximity of the motor so that should the need arise the motor can be disconnected for safe maintenance or in an emergency. The motor will work directly connected, but you will create a safety issue.

There is only two test you can do measure on the Ohm scale the resistance at the power connection if there is a reading then it means it's not open but that's not an indication that the motor is Ok, then measure on the MOhm scale between the body of the motor and any of the power connections if there is a reading then the motor have a internal short, the best is to open the motor and inspect it for black spots on the coils your nose is the best test smell it

There isn't or shouldn't be any power in coaxial cable. It is just for the TV or computer hook up. Just so you can receive the signal from the broadcaster or Internet.

In several ways the previous answer is wrong.

Firstly coaxial cable is exactly like normal 2 wire cable (fig8 cable) except that instead of two separate wires running side by side separated by insulation) one wire is inside the other (again separated by insulation). There are many different types of coax (probably hundreds eg one i use is rg-58 which is for two way radios, another is rg-6 which is used for tv coax)

secondly- if any signal is to be passed through a cable- there has to be power flowing through it- it may be incredibly small (microvolts like from your tv antenna) or very large (hundreds of volts like in a high powered radio transmitter)

Even in a tv coax, if you have a `masthead amplifier' that only has 1 cable running up to the antenna and a funny box behind the tv that has 2 coax leads running into it and a plug-pack from a PowerPoint going into it as well- you would find that you are actually passing power up the coax from the PowerPoint plug-pack to the electronics up on top of the tv mast - power going up and tv signal coming down the same coax at the same time- saves on another two wires having to be run!!!

Many `cable' tv or internet cables have a similar `power over coax' arrangement for powering amplifiers on long cable runs, this is normally stopped by a filter before the end users outlet however (if the filter is faulty this can be the `tingle or zap' that you sometimes get when touching the outer screw connector of the coax plug)

The voltage can be either 250000 kilovolts or 240 volts, it can't be both so the question can't be answered.

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There are zero amps in 250,000,000 volts. Amps can be found using the following equations. Amps = Volts/Resistance in ohms, Amps = Watts/Volts and Amps = Sq root of Watts/Resistance in ohms.

Simply put, a single phase supply has one or two hot wires, may have one neutral wire, and (hopefully) one ground wire. A three phase supply has three hot wires, and may (wye connection) or may not (delta connection) have a neutral. It also will have a ground wire. A more complex explanation involves the phase difference between hot wires. For three phase there is a 120 degree phase difference between each of the three possible pairs of hot conductors A-B, B-C, C-A. For single phase, since there is only one possible pair of hots, there can be no difference.

From the Cessna factory.

The question cannot be answered without more information, such as the current or power.

If you have three adjacent houses each with a single-phase supply taken from different phases in a three-phase cable in the street, the total power is equal to the sum of the powers in each of the three phases.

If the fuse thsat has blown is a 3 amp, you should only replace it with a 3 amp fuse, which is good for appliances up to 700 watts (In the UK, on 240 volts). Do not replace a 3 amp fuse with a 13 amp fuse, it gives much less protection. If you replace a 13 amp fuse with a 3 amp fuse, the 3 amp will likely blow, since the 13 amp fuse should be protecting a powerful appliance such as a heater, between 2000 watts and 3000 watts.

There actually is no such thing as 2 phase. You either have single phase (As most/all residential services), or three phase (primarily in commercial/industrial). When a normal three phase motor 'loses a phase' (blown fuses, open winding, bad contactor, etc...) if it continues to operate, it is considered 'single phasing'. While such operation is typically only briefly. (They usually don't run long) While it probably will not operate very long, the motor would over heat, and loose speed rapidly, and they will sometimes make noise. If you need to operate a three phase motor on residential service, you will need a 'three phase converter' (some people call them 'inverter's) to electronically convert single phase power into three phase, but they are usually only practical for smaller three phase motors.

5 hp equals 3730 watts, and on a 3 phase 480 v system the line voltage is 277, so the current times 277 times 3 equals 3730. The answer in theory is 4.5 amps.

But you have to allow for 10% power-loss in the motor, and also the power factor, which could be 0.8.

Therefore the current is probably 6 to 6½ amps. Maybe 10 amps on starting up.

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The formula you are looking for when amperage is desired when horsepower is shown is - I = HP x 746 / 1.73 x volts x % efficiency x power factor.

A standard motor's efficiency between 5 to 100 HP is .84 to .91.

A standard motor's power factor between 10 to 100 HP is .86 to .92.

Amps = 5 x 746 = 3730/1.73 x 480 = 3730/830 x .84 x .84 = 3730/586 = 6.37 amps. Starting current will be 300% of the motors run current.

You have to wire both the run and start windings. The start windings will automatically be removed from the circuit once the motor is at 75% of normal speed. The start winding gives you more torque to start the motor.

The formula for the electric current can be given as I= Qt where Q refers to coulomb charge and t= amount of time in second . By applying this formula the amount of current passing through the conductor can be known foor any instant of time. For any conductor the amount of charge is always constant.

Current measures the flow of moving charge per unit time. Therefore the formula for current is I=Q/t as the unit of current is C/s (Coulomb's per sec) or amps (A).

Three Phase conversion from KW to Amps, but you have not supplied enough info. Use whatever formula below works with the rest of the data you have.

E =VOLTS P =WATTS R = OHMS I =AMPS HP = HORSEPOWER

PF =POWER FACTOR KW = KILOWATTS KVA = KILOVOLT-AMPS

EFF = EFFICIENCY (decimal)

When P, E and PF are known: P / E x PF x 1.73

When HP, E, EFF and PF are known: HP x 746 / E x EFF x PF x 1.73

When KW, E and PF are known: KW x 1000 / E x PF x 1.73

When KVA and E are known: KVA x 1000 / E x 1.73