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What is the proof line current is equal to square root of 3 times of phase currents?
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At what condition the phase angle equal zero?
That means that the voltage and the current are in phase.
Which is greater 1kw equals equals KVA?
In the case of DC, and in AC when current and voltage are in phase, a volt-ampere is the same as a watt (and therefore, a kilo-volt-ampere is the same as a kW). In the case of AC, when current and voltage are NOT in phase, power = voltage x current x power factor; the power factor is the cosine of the angle between current and voltage, and it is always less than or equal to one. In such a case, a kVA would be less than a kW.
Why should always be power factor less than 1?
Power factor can also be equal to 1. Power is greatest when voltage and current are in phase; the "power factor" is used to specify how much less the power is, compared to the product of voltage x current, if they are not.
What is the function of neutral CT?
A CT is a current transformer, used to measure current flow in a conductor. Neutral is power return, usually grounded at the distribution panel. A neutral CT, then, is a device that measures the current flow in the neutral conductor. In a three phase star system, each phase returns current to neutral, but the three phases cancel each other out, resulting in effectively zero current in neutral. The neutral CT is used to detect an imbalance in the system, perhaps caused by a ground fault or by some failure in one of the phase loads. In a single phase, single ended system, there is current on neutral, so the value of a neutral CT is not so great. If you also had a hot CT, you could compare and detect imbalance between hot and neutral, which would be an indication of a ground fault. (Actually, a ground fault current interrupting device, also called a GFCI, usually compares current in hot and neutral simultaneously, because both conductors are wound together as the sensing transformer primary - any perceived current is a ground fault.) In a single phase, double ended system, such as the 120/240 split phase system used in the US, a current CT could indicate ground fault or a system imbalance but, usually, imbalance might be a normal situation as various loads are turned on and off.
What is the equation of (3-1)?
The voltage of a winding that is connected in star is 1 over the square root of three, 1 / 1.732, or 0.5774, of the voltage if that winding were connected in delta. This results in a star power of 1/3, or 0.3333, of the delta power.Similarly, if you know the winding current in delta, you can calculate the star current by multiplying by 1.732.This all presumes that the neutral point of the star is symmetrically centered in the middle of the phase triangle.
What is the resultant current in parallel circuit combining of 2 or more currents that are in phase?
The phasor sum (kind of like a vector sum) of the legcurrents in a parallel network will equal the current entering the network. If all currents are in phase, then just add up the magnitudes of the currents.
What is the formula to get neutral current in three phase transformer where three phase cureent are given?
Neutral current is the vector sum of the phase currents. You should be able to add up the phase currents from their polar quantities.
Why line current is greater than phase current in delta connection?
Because if you apply Kirchhoff's Current Law to the junction between the line current and the two phase currents, the line current is the phasor (vector) sum of two phase currents. For a balanced load (only), this works out to 1.732 x phase current.
What is the difference between Load Current Line Current and Phase Current?
A load current is a current drawn by an electrical load. In other words, it is the current flowing from the source to the load.For a single-phase system, a line current is a current flowing through the line, or 'hot', conductor, while the current through the neutral conductor is called the neutral current.For a three-phase system, the three 'hot' conductors between the load and the source are called 'lines' and, so, the currents passing through them are called 'line currents'. For a three-phase system, loads are either connected between line conductors (delta-connected system) or between each line and the neutral (star- or wye-connected system), and represent the phases -so the currents passing through the loads are called 'phase currents'.For a balanced three-phase system, the line current is 1.732 times the value of a phase current, where the phases (loads) are connected in delta. For phases (loads) connected in star (or 'wye') the line current is numerically-equal to the phase currents.
What is difference between line current and phase current?
A phase current is the current passing through a phase, whereas a line current is the current flowing through a line.In the case of a balanced delta-connected load, IL = 1.732 IP. In the case of a balanced star-connected load, IL = IP.For unbalanced loads, these relationships don't hold true, and must be individually calculated.
Is line to line voltage equal to line voltage?
Yes. By definition, a line-to-line voltage is indeed called a line voltage.For delta-connected, three-wire, systems comprise three line conductors. The line voltage is numerically equal to the phase voltage.For wye-connected, four-wire, systems comprise three line conductors and a neutral conductor. Any line-to-neutral voltage is called a phase voltage. The line voltage is 1.732 times the value of the phase voltage.
Can different size conductors be used on a three phase supply?
In normal use a 3-phase supply is balanced so that the three phase wires would be of equal size because they carry equal current. When in balance the system draws no current in the neutral wire (if present). In some conditions different currents are taken from a 3-phase supply, for example three houses connected to the different phases will probably take different currents, and in that case the neutral could carry a current up to or equal to that in one of the phase wires. Therefore in supplying a street, the four wires of a 3-phase supply would all be of equal size.
What is mean by Zero phase Current transformer?
at first what is zero sequence current.. Zero sequence currents, in simple terms, are those found in the neutral conductor. They include the unbalanced 50 Hz currents and the 3rd, 9th, 15th and other triplen harmonic currents. Zero sequence currents appear in the neutral because they do not cancel in the way that 50Hz currents cancel. This is due to the fact that the zero sequence component on one phase is always in phase with the zero sequence components of the other 2 phases. we can say 50 Hz current on one phase, on the other hand, is always 120° out of phase with the other phases 50 Hz current which causes their balanced portions to cancel in the neutral. now, any method of ground current sensing involves detecting zero sequence currents. For solidly grounded systems, connecting the phase current transformers together with a common return allows measurement of zero sequence current in the common lead, if there is no neutral load current. The vector sum of the phase currents is equal to the zero sequence ground current. Under normal load conditions, the vector sum of the three phase currents is near zero. It is not exactly zero as the system capacitive charging current of the load circuit is non-zero. but it is limited value..if it is beyond the limit this zero sequence CT take care of it. All phase conductors are passed through the window of a single CT referred to as a zero sequence CT. Under normal circumstances, the three phase currents will sum to zero resulting in an output of zero from the zero sequence CT's secondary. If one of the phases were shorted to ground, the sum of the phase currents would no longer equal zero causing a current to flow in the secondary of the zero sequence CT. This current would be detected by the relay as a ground fault. Regards, Balaji K APL, Ahmedabad
How do you calculate amperage of a 3 phase transformer?
Total KVA of the transformer divided by (square root of 3 times the voltage). This will give the individual phase currents. These individual phase currents will be 120 degrees out of phase with each other.
Is the neutral conductor of a two wire single phase circuit considered a current carrying conductor?
Sure. In a two-wire circuit, both wires carry equal currents.
What if the fourth wire in a three phase is having impedance would the current in the neutral line remain to have a value of zero?
When the system is in balance, with three equal phase currents, there is no current in the neutral 4th wire and it is not needed. However if the load is unbalanced, the neutral is needed to maintain the star point at zero volts.So for example a street of houses fed by a 3-phase supply needs a neutral because the houses draw unequal currents from the different phase lines, although a large enough collection of houses would tend to balance itself out.If a three-pase system has equal currents the current in the neutral is zero. If two phases draw equal current but the third has no load, there is an equal current in the neutral, and if one phase draws current but the other two have no load, there is again an equal current in the neutral.ANOTHER ANSWERA three-phase, four-wire, system comprises three line conductors and a neutral conductor. If the load supplied by this system is balanced (i.e. the loads connected between each line and neutral are identical in all respects), then no current will flow in the neutral conductor regardless of its impedance. If the load is unbalanced, then a neutral current will flow in the neutral conductor. In other words, the impedance of the neutral conductor plays no part in whether or not there is a neutral current.
Should all three phases of 3 phase motor are to be equal on no-load and load conditions?
Ideally all three phase currents will be equal. There may exist some voltage imbalance from the power source, which will result in unequal currents.
