Electrical Wiring

Not true.

This statement is true as long as you are insulated and isolated from any surrounding grounded material. By adhering to these conditions you do not provide any return path for the current to flow. On the odd occasion when an electrician has to work equipment "hot", it is only done with one hand while the other is secure in his pocket so as to not accidentally touch any of the surrounding grounded framework.

If you have any doubts about an answer that you get, check the answerer's bio by clicking on their name to check their qualifications.

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 REALLY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS.

=== === Not exactly. Breakers trip because the current exceeds the rating of that breaker. In other words....you're plugging too much into that circuit. And the wire can only safely handle a certain amount of current; so you can't just put a bigger breaker in. === === <><><> (LIFE SAFETY WARNING! [disclaimer]

Electricity is dangerous!

You can be injured or killed!

Improper installations can cause fire, injury and death!

The only time I would expect "upgrading" your service would help you to stop tripping breakers was if it was the main breaker that was tripping, and that because of overload [high current]!

It is possible that the panel is poorly maintained and the breakers do not connect to the busbar snugly, allowing a voltage drop at the connection point. This would generate heat at the connection which would contribute to the breaker tripping if it has a thermal trip as well as a magnetic element. It would also contribute to lowered voltage at the intended load, which could cause higher current draw in some cases [motors]

On the other hand, I have found that some unscrupulous tradesmen will use the opportunity to sell a big job because they need the work, rather than fix a simple problem.

I recently had a service call where the people complained that "everything goes out all over." They could have been sold a new service by someone, even though theirs wasn't that old ... but all they needed was to have additional breakers installed.

Somebody had put three circuits into one breaker and two each into two others, so they had three breakers instead of seven.

The usual real solution is to run a new line for new receptacles to the point of high demand and leave the rest of the wiring alone. Home handymen and many remodelers who do their own electrical work often just dump anything they add onto any existing circuit. <><><>

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.

500Mw at 11kv works out to 45000 a

a bit big for any wire manufactured on this planet

suggest you go to a more practical voltage like 132,000V

Since we are inevitably talking about a three-phase transformer, the line current is determined from

IL= rated apparent power / (1.732 x UL) = (500 x 106) / 1.732 x 11 x 103)

...which works out at 26 244 A which, as the original answer suggests, is not a practical value for this combination.

=== === Fuse wire is just as its name implies: it is some wire made specially to carry only a certain amount of current, which is known as its "designed failure current", when it is being used in a cartridge or a rewirable a fuse carrier that is wired with a certain length of the fuse wire. If the current passing through the fuse exceeds that designed failure current the fuse wire gets so hot that it melts and breaks the circuit. That should help to protect the power supply cables from being overloaded as well as protecting the supplied appliance or appliances from being damaged. In either case the fuse should help to prevent a dangerous fire from starting. A fuse may also help to prevent a person using an appliance from getting a dangerous electric shock but that is not the main purpose of fitting a fuse.

The main purpose of fitting a fuse is for overload and fire protection. Earth wire is, again, just as its name implies: it is wire used to connect the frames and outer casings of appliances and power supply panels to the earth. See the related question and answer for more details about this.

=== === <><><> It is easier to say what is similar, since they are completely different things.

They both conduct electricity, are usually made of metal, and both are important to safety. Other than that, they are nothing alike.

A fuse is a device that breaks the circuit when the current exceeds a predetermined value.

An earth wire, also called the ground wire, as the name implies, connects a circuit or a device to ground.

For sine waves:

To calculate the RMS value of a sine wave, multiply the peak value by 0.707. The peak value is, of course, one half the peak-to-peak value. To go the other way, reverse the order of operations. That is, if you're starting with an RMS value, divide by 0.707 and then multiply by two to get the p-p value. Another way to convert from RMS to p-p is to multiply the RMS value by two square roots of two: RMS x 2 x SQR(2).

Or more simply, to convert from RMS to peak to peak voltage:

(RMS x 1.414) x 2=P-P

For example:

120vac x 1.414= 170vac

169.68vac x 2 = 339.36vac P-P

Where there is a significant reactive component in the characteristic of the cabling or load, we must also consider the effects of the X/R ratio. The real vs imaginary components of the impedance:

V(peak) = V(rms) * sqrt(2) * (1+ e(exp -pi/(X/R)))

where "exp" is the exponent to which the value of e is raised.

Reading the power of e above in English:

"e to the power of (minus pi divided by the X/R ratio)".

Take careful note of the top line of the first answer "For sine waves". More specifically the formula applies only to a signal which is a pure sine wave (a single frequency, no harmonics or other frequencies). As soon as you combine two or more sine wave signals of different frequencies, the ratio of peak voltage to RMS voltage depends strongly on the phases of the component signals. Too complicated to answer here, in full explanation.

Vrms = (Vp-p / 2 )/ sq.root (2) = Vp-p / 2.828 for sinusoidal waves..

*Note: If the signal or the waveform is not sinusoidal you'll have to derive from basic steps with a sound knowledge about integrations.

RMS = root mean square = square root (mean(square values of voltages))

This answer has been temporarily closed to changesbecause so many askers have been repeatedly splitting-off variants of the question such as "Can you give me simple diagram for star-delta starter".

Please note: diagrams cannot be included in answers.

The answer given includes plenty of details for anyone to be able produce a simple diagram showing how a 3-phase motor can be wired in star and delta configurations.

To be able to wire a 3-phase motor either in star or delta, all 6 ends of the three sets of coils, called "windings", have to be exposed with suitable connection terminals.

The windings are often labelled A1, A2, A3 and B1, B2, B3, where "1", "2" and "3" denote the separate phase windings and "A" and "B" denote the beginning and end of each winding.

Another way of describing it is to say that the separate windings can be labelled:

Winding 1: A1 <---> B1. Winding 2: A2<---> B2, Winding 3: A3 <---> B3.

In star configuration either all the A's or all the B's are connected together and the 3-phase supply (consisting of three separate "phase lines" labelled L1, L2, L3) is connected to the remaining three connectors. For example, if you connect B1 to B2 and B2 to B3 to form the center of the "star" then you must connect supply L1 to A1; supply L2 to A2 and supply L3 to A3.

In delta configuration, connect B1 to A2, B2 to A3, B3 to A1. (If you draw that out as a schematic diagram, it will be a triangle.) Then connect supply L1 to A1; supply L2 to A2 and supply L3 to A3. (Exactly the same as the supply lines were connected before, for the star configuration.)

The initial making of those connections in "star" - and subsequent changing into "delta" after the motor has built-up sufficient speed - would all normally be handled by a "star-delta motor starter" unit. A good tip: before you ever start hooking one up, study its schematic wiring diagram carefully to be sure you really understand which of its terminals connect to which motor terminals, and where to connect each line of the 3-phase service cable.

Note:

Some 3-phase motors use an alternative way of labelling the windings: 1A, 1B, 1C and 2A, 2B, 2C.

Electronic motor-control systems, which offer soft-starts in DELTA configuration, are now replacing the use of manual or semi-automatic star-delta starters.

<><><>

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.

Firstly all voltages and currents should be in RMS values. (divide peak values by root 2).

Apparent Power

|S| = VI = (P2+Q2)0.5

Complex Power

S = P + jQ

P = |S|cos(theta)

Q = |S|sin(theta)

theta = phase angle between voltage & current (can be calculated by finding total impedence of the circuit)

Power Factor = cos(theta)