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Electrical Wiring
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The value of the voltage (potential difference) across a conductor when a current of one ampere dissipates one watt of power in the conductor. It is also equal to one joule of energy per coulomb of charge, J/C. Unit conversion: V = W/A = (J/s)/A = J/As = J/C where V=volt, W=watt(power), A=ampere, s=second, C=coulomb(charge)
How does an earth-leakage circuit breaker or ELCB work?
An Earth Leakage Circuit Breaker - ELCB for short - was the first name given to what is now called a Ground Fault Circuit Interrupter (GFCI) .
The early, original, type of ELCB was designed only to detect a current flowing in the safety "ground" or "earth" wire.
Why was that important?
If there is no fault anywhere in a circuit supplying single-phase alternating power to a unit such as an electrical appliance, machine or other equipment, the current flowing to the unit at any instant in the "hot" or "live" wire should exactly match the current flowing away from the unit in the neutral wire. Similarly, there should be no current flowing in the unit's safety "ground" or "earth" wire.
It is a basic fact of electrical engineering design that all current flowing to an electrical appliance, machine or other equipment from the power generation station via its supply circuit's "hot" or "live" wire should only return to the power station via that same circuit's "neutral" wire.
So, as a result of that basic fact, if any current isflowing in the ground wire, it must be caused by a fault condition and the supply of current to the circuit needs to be stopped urgently.
Many years ago, before today's electronic RCDs or GFCIs were designed, much simpler electro-mechanical relays called Earth Leakage Circuit Breakers (ELCBs) were invented so that, if any such ground current exceeding just a few milliamps was detected, they would "trip" - meaning "operate" - to break the current supply to the circuits for which they were installed to protect.
The original type of ELCB did not check for any difference in current flowing in the live and neutral wires, which is another indication of a very serious fault condition - even if no current can be detected flowing in the ground wire - because the "missing current" may actually be flowing to ground via someone's body!
When RCDs were invented, most manufacturers of GFCIs adopted the same technology because it offers so much more protection to users than the original GFCI could ever give.
In the US and Canada such devices are still commonly known as "GFCIs" or "GFIs" even though they have the additional "residual current detector" functionality, whilst in Europe and elsewhere the more accurate name of "Residual Current Detector" or RCD has been widely adopted for general use instead of using the name of the much simpler GFCI device.
Another answer [Note: this is actually a description of a GFCI, not of an ELCB.]
An ELCB works by comparing the input current in the "hot" line feeding a load and the return current in the "neutral" line coming back from that load.
If the return current is less than the input current by a quite small amount - usually only about 30mA or less (mA = milliamps, which are thousandths of an amp) - it means there must be a leakage current.
That very small difference between the input and return currents is what the ELCB is designed to detect and cause it to trip so as to break the flow of current to the load.As the name itself indicates, an Earth Leakage Circuit Breaker device always checks for any leakage of current. The leakage may be either to the "earth" or "ground" wire or to something else such as the user of the equipment that is being protected by the ELCB device.
What will be the current flow of a 3 hp motor supplied with a 120 volt service?
1hp= 746Watts. So, now, we can take a simple power equation of
P= IV, Solve for I, I=P/V, and plug in 746 x 3 for Power, and 120V for V.
475 amps, per NEC 310-16. Note that this is a maximum; there are many reasons to derate the current carrying capacity of the wire.
What are the advantages and disadvantages of parallel connection of generators?
The advantage of generators in parallel is that the total electrical power output of the generators are additive.
The disadvantage of generators in parallel is the additional equipment and the extra cost of that equipment, that is needed to syncronize the generators. This extra equipment also must keep the generators in parallel and not let one generator take the lead. If this happens, that generator will take the full load and probably trip off line. This action then overloads the other paralled generator an then it to will trip off line.
How many volts is there in a single phase?
The number of Volts in a residential service drop in the US is either 120V 2 Wire, 120V-208V Network, or 120-240V 3 Wire. A 120-208V Network service is not single phase, but its 120V portion is.
How do you wire a 220 volt 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.
How many output amps is a 75 kva transformer?
For single phase, KVA = (line to ground) * (phase current).
A 75kVA 480 to 208Y/120 volt transformer is a fairly common transformer. I assume this is the type of transformer you are referring to. 75k / 120 = 625 Amps.
As an FYI, the 208Y voltage is the line to line voltage, which is equal to (phase 1) - (phase 2), where the phases are separated by 120 degrees, thus (phase 1) * 1.732
For three phase, kVA = (line to line voltage) * (phase current) *(sqrt 3),
75k / 208 / 1.732 = 208 Amps.
Does an inductor absorb electrical energy?
Yes, both capacitors and inductors are capable of storing energy. Capacitors store electrical energy in form of electrical charge and inductors in form of magnetic field.
- Neeraj Sharma
What is the possible cause if three phase motor has imbalanced current on winding?
It sounds like there may be a partial short in one the the three motor windings. What should be done it to megger the motor. This will tell you if all three winding are not shorting to each other and not shorting or partial shorting to ground. If the reading is over 2 megohms to infinity then the motor is all right. Below .5 megohms (500000 ohms) the motor should be cautiously used and will probably have to go in for a rewind.
If the burning is in the motors junction box then the burning could be caused by loose conections between the feeder wires and the motor winding leads.
What is the difference between single phase and three phase voltage measurement?
Phasing, or the number of phases in an electrical system has nothing to do with the voltage. A single phase and three phase supply could have a voltage supply of any given voltage from virtually 0 to infinity. Most single phase power supplies in the US are 120/208-240 volt. Three phase power supplies are typically 120/208 to 277/480 volt.
What is the formulae for a 3 phase circuit to calculate the power?
watts = volts * amps * 1.73 * power factor
If the load is resistive, such as a heater or incandescent lamp, use 1.0 for power factor.
For reactive loads such as motors, the power factor is usually found on the nameplate.
Comment
More specifically, for a balanced load (and ONLY for a balanced load) power is the product of 1.73 and the line voltage and the line current and the power factor.
What the effect of high neutral current in 3 phase system?
The neutral current in a three-phase, four-wire, a.c. unbalanced load is the phasor-sum (vector-sum) of the three phase currents. That's more-easily said than done, as the maths can be quite difficult -certainly too difficult to explain in WikiAnswers, so you should refer to a textbook which covers the topic. Probably the best approach is to use the 'a-operator', the equivalent of the 'j-operator' used for single-phase loads.
How to wire a split capacitor motor?
Your two hot wires go to the load side of your contractor and the two brown wires go to your capacitor
What does the inside of a 3 phase transformer look like?
A three phase transformer has three primary coils and three secondary coils wound on a laminated iron core shaped like the capital letter 'E'. Each pair of primary and secondary coils are wound concentrically onto each leg of the 'E'. There is a straight , laminated core segment, that connects across all three legs of the 'E', forming a circuit path for the magnetic flux.
The primary and secondary coils can be arranged as an autotransformer, with the primary and secondary coils connected end-to-end, with a common conductor tapped at the interconnection, or as separate coils with two separate connections for each coil.
87 amps three phase means 87 amps on each phase.
Additional Answer
It's only 87 A per phase for a wye (star) connected load; for a delta connected load, the current per phase will be 50 A, while each line current will be 87 A. That's assuming a balanced load, of course. Line currents pass through the supply conductors to the load, whereas phase currents pass through the loads themselves.
Next answer: No, 87 amps three-phase means 87 amps on each phase wire, so you can put an ammeter in each wire and it registers 87 amps.
It doesn't matter whether the load is connected delta or star :) But the amount of power is different because the line-to-line voltage is sqrt(3) times as much as the line-to neutral voltage. It isn't the current that is different, it's the voltage.
Another AnswerThis question is rather confusing as we don't really know what the original '87' A is referring to. Is it a line current or a phase current? But it's important that we use the correct terminology if we are to sort it out.
First of all, the 'hot' conductors that connect the generator to its load are called line conductors (or, simply, 'lines'), and the voltages between any pair of line conductors are termed 'line voltages', while the currents flowing through each of them are termed a 'line currents'. (Confusion exists when people call these three interconnecting conductors 'phases', which is common but completely incorrect! Remember, 'line' voltages and currents are so-called because they refer to 'lines', not phases!)
Next, the three windings within the generator, which may be connected either in delta or in star (wye) represent the machine's 'phases'. So the voltage appearing across any one of these internal windings is called a 'phase voltage', while the current through any one of these windings is termed a 'phase current'.
Generally speaking, while its very easy to place a voltmeter and ammeter to measure line voltages and line currents, it's usually very much more difficult to place these instruments so that they can measure phase voltages and currents, This is because the phases are inaccessible, because they are enclosed insidethe generator.
So, in practise, whenever we work with a generator (and the same goes for a motor), we usually measure line values notphase values.
So, returning to the question, if we assume the '87 A' quoted by the questioner is a phase current (that is, as measured in any winding inside the generator) then, for a balanced load, the value of the line current (as measured in any one of the external line conductors) will depend on whether the windings are connected in delta or in star. If the windings are connected in star, then the line currents (i.e. outside the generator) will have exactly the same magnitude as the winding (phase) currents -i.e. they will also be 87 A. If, on the other hand, the windings (phases) are connected in delta, then each line current will be 1.732 times the phase current -that is, about 151 A.
On the other hand, if the '87 A' quoted is a line current (that is, as measured outside the generator) then, for a delta-connected generator, the winding (phase) current will be 0.577 times the line current: i.e. about 50 Awhereas, for a star-connected generator, the winding (phase) current will be exactly the same as the line current, i.e. 87 A.
Next Answer: the longer it gets, the more confusing it gets :) However the wires carrying the three-phase supply can correctly be called 'lines'. Then you can have a 'line-to-line' voltage and a 'line-to-neutral' voltage and those terms are unambiguous. At the generator or load, if it's star-connected, the line current equals the generator or load current. When the generator or load are delta-connected, the line current splits two ways and the generator/load current is 1/sqrt(3) times as much as the line current.
The confusion is based in calling one condition 'line' and the other 'phase'.
All this assumes a perfectly balanced system.
Why three phase motor has the better performance when compare to single phase motor?
If you are asking what is the advantage of a motor wound for a Y or Delta configuration over a motor wound for a single phase configuration, then the advantage of the Y or Delta motor is more efficient operation. And in a motor, or in any power application, efficiency is all important.
How do you convert single phase kva to three phase kva?
Va=volts x amps. The K stands for one thousand. So 1 Kva is one thousand watts. So 415v times 120a= 49,800 what's. You divide that by a thousand and you get 49.8. So it would be 49.8 Kva.
Can a 3 phase motor be wired to run in your house?
The physical internal windings between single phase and three phase motors makes this an impossibility That being said money can make anything happen. Depending on the amount of money you want to spend to make this happen there is a device on the market called a VFD ( Variable Frequency Drive). On the three phase input terminals you apply your single phase voltage. On the output terminals you connect your three phase motor. When run in this configuration there is an internal switch that has to be changed to let the VFD know that it should be looking for only two lines on the input to be hot. Otherwise the VFD thinks that there is a line loss on the three phase input terminals and the unit will not start. <<>> You can make a phase converter with a couple extra motors. Wire up a 120V single phase motor and couple it to a 3 phase motor. This turns the 3 phase motor into a generator for you to run to whatever equipment the 3 phase motor is. Although if you had a single phase motor you probable don't need a 3 phase motor. == == <<>> yes! you will have to buy a phase converter. <<>> yes, it is possible to this with a rotary phase converter . one manufacturer is "phase master" (as an example only, not wishing to promote any brand). these are not cheap units and it may be more cost effective to purchase a single phase (220V.) replacement motor . the overall efficiency (operational costs) would be better too . a rotary phase converter is usually the "last choice on the list" .
What three values in an electrical circuit are connected by Ohms law?
Ohm's Law simply states that, under certain circumstances, the current (I) passing through a circuit is directly-proportional to the potential difference (U) applied across that circuit.
So, strictly speaking, Ohm's Law, relates just twoquantities: current (expressed in amperes) and potential difference (expressed in volts).
The ratio of potential difference to current is, of course, resistance (R). So, by extension, Ohm's Law can be written as R = U/I. But, strictly speaking, resistance is not mentioned in Ohm's Law.
However, it must be realised that Ohm's Law is NOT a universal law; in other words, it does not apply in all circumstances. In fact, it does not apply to a great many electronic devices, such as diodes, etc. In fact, it only applies to pure metal conductors provided their temperature remains constant for variations in voltage.
Why the voltage between phase to neutral is 240v compared to phase to phase is 415v?
What you are describing is a three-phase, four-wire, system having a phase voltage of 240 V and corresponding line voltage of 415 V.
You do not add the three phase voltages (3 x 240 = 720 V) to obtain a line voltage.
The three phase voltages are actually displaced from each other by 120 electrical degrees, so any pair of phase voltages must be vectorially-added to obtain a line voltage. If you perform this calculation, you will find that the line voltage is always 1.732 times larger than the phase voltage. So, 1.732 x 240 = 415 V.
