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How you measure power factor in three phase load by two wattmeter method?
Wiki User
∙ 11y ago
First of all, you can only measure power factor of a three-phase load, provided that it is balanced load. The power factor can then be found by determining the cosine of the phase angle, using the following equation:
tan (phase angle) = 1.732 ((P2-P1)/(P2+P1))
...where P1 and P2 are the readings of the two wattmeters.
Wiki User
∙ 11y ago
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How would you measure power factor of the balanced three phase load by two wattmeter method?
Yes. The wattmeter's current coil will have to be connected into one of the line conductors, and its voltage coil between that same line conductor and the neutral point of the load. Connected this way, the wattmeter's voltage coil is measuring one of the three phase voltages (line-to-neutral voltage) while its current coil is measuring the corresponding phase current (for a 4-wire system, the phase current = line current). The power factor (cosine of the phase angle) is accounted for automatically within the wattmeter. So the wattmeter will measure the true power (in watts) of one phase. The total power, therefore, will be 3x the wattmeter reading -providing, of course, that the load is balanced (i.e. each phase is identical). WebRep currentVote noRating noWeight
Will the two-wattmeter method work for all three-phase loads eg unbalanced loads inductive loads capacitive loads and delta-connected loads?
Blondel's Theorem tells us that, to measure the total power of a three-phase load (balanced or unbalanced), we can use one less wattmeter than there are conductors supplying that load.So the two-wattmeter method will work for anythree-phase load, provided there are only threeconductors supplying that load, e.g. three-wire delta or three-wire star (wye).Bear in mind that wattmeter's read true power (expressed in watts) and ignores the reactive power of inductors and capacitors.
Why does not wattmeter measure the reactive power?
A wattmeter is designed so that it measures the supply voltage and the in-phase component of the load current. The product of these two quantities is the true power of the load.
How would you measure power using three watt meter and one watt meter for balanced and unbalanced loads?
The 'one wattmeter method' can only be used for balanced, wye-connected, loads where the load's neutral point is accessible. The wattmeter's current coil is inserted into any line conductor, and the voltage coil is connected between the same line and the neutral point. The wattmeter reading indicates the power of one phase, so the total power is three times the wattmeter reading.To measure the total power of a balanced or unbalanced wye- or delta-connected load, it is only necessary to use twowattmeters -this is called the 'two wattmeter method'. In this case, the current coils of each wattmeter are inserted into any two line conductors, and the voltage coils are connected between the two line conductors and the third line conductor. The sum of the two wattmeter readings will indicate the total power of the load.
Why use two wattmeter to calculate the power of a three phase load?
Two wattmeter method is used in a three phase sysstem to measure the true power without regard to the balance ie. It can be used to measure both balanced loads and unbalanced loads.The three phase power could be measured using single phase wattmeters in each loads of the system. But using three wattmeters is quite unnecessary as we can measure it by using only two wattmeters.The three phase power could be measued by using single phase wattmeters , haing a current coil in one line and a potential coil connected between the line and some arbitrary common junction point. If that arbitrary common point is chosen on one of the three lines, then the wattmeter connected to that line will indicate zero power because it's potential coil has no voltage across it. hence, that wattmeter may be eliminated, and the three phase power can be determined by means of only two single phase wattmeters.
Is it possible to measure power factor of the balanced three-phase load by two-wattmeter method?
yes.
How would you measure power factor of the balanced three phase load by two wattmeter method?
Yes. The wattmeter's current coil will have to be connected into one of the line conductors, and its voltage coil between that same line conductor and the neutral point of the load. Connected this way, the wattmeter's voltage coil is measuring one of the three phase voltages (line-to-neutral voltage) while its current coil is measuring the corresponding phase current (for a 4-wire system, the phase current = line current). The power factor (cosine of the phase angle) is accounted for automatically within the wattmeter. So the wattmeter will measure the true power (in watts) of one phase. The total power, therefore, will be 3x the wattmeter reading -providing, of course, that the load is balanced (i.e. each phase is identical). WebRep currentVote noRating noWeight
Why is one watt meter method of power measurement not applicable to unbalanced circuits?
The one wattmeter method will only measure the power of the phase to which it is connected. So, by reconnecting it to measure each phase separately, you can measure the power in each phase in turn, and add them up to give you the total power.
Why do you use two phase watt meter?
You may be thinking of the 'two-wattmeter method' for measuring three-phase power?As a rule, it's always possible to use one less wattmeter than the number of conductors supplying a three-phase load to measure the power of that load. So, for a three-phase, three-wire, system, two wattmeters may be used to measure the total active power of the load -regardless of whether the load is balanced or unbalanced. The algebraic sum of the two wattmeter readings will give the total power.
Why you use two watt meter method?
The two-wattmeter method can be used to measure power in a three-phase system. Each current coil is connected in series with one of the live phase wires, while the voltage coils are connected between those and the third live wire.
Will the two-wattmeter method work for all three-phase loads eg unbalanced loads inductive loads capacitive loads and delta-connected loads?
Blondel's Theorem tells us that, to measure the total power of a three-phase load (balanced or unbalanced), we can use one less wattmeter than there are conductors supplying that load.So the two-wattmeter method will work for anythree-phase load, provided there are only threeconductors supplying that load, e.g. three-wire delta or three-wire star (wye).Bear in mind that wattmeter's read true power (expressed in watts) and ignores the reactive power of inductors and capacitors.
Why you use upf wattmeter for short circuit test on load test on single phase transformer?
If, by 'upf', you mean 'unity power factor', then allwattmeters measure the in-phase component of the load current, so the term is quiet unnecessary.A short-circuit test is used to determine the (true) power loss in the transformer, which is exactly what a wattmeter measures
Why does not wattmeter measure the reactive power?
A wattmeter is designed so that it measures the supply voltage and the in-phase component of the load current. The product of these two quantities is the true power of the load.
How would you measure power using three watt meter and one watt meter for balanced and unbalanced loads?
The 'one wattmeter method' can only be used for balanced, wye-connected, loads where the load's neutral point is accessible. The wattmeter's current coil is inserted into any line conductor, and the voltage coil is connected between the same line and the neutral point. The wattmeter reading indicates the power of one phase, so the total power is three times the wattmeter reading.To measure the total power of a balanced or unbalanced wye- or delta-connected load, it is only necessary to use twowattmeters -this is called the 'two wattmeter method'. In this case, the current coils of each wattmeter are inserted into any two line conductors, and the voltage coils are connected between the two line conductors and the third line conductor. The sum of the two wattmeter readings will indicate the total power of the load.
How would you measure power using three wattmeter in three phase?
Each of the wattmeter's current coils are inserted into line conductors, and the voltage coils are connected in wye between each line conductor.
Why use two wattmeter to calculate the power of a three phase load?
Two wattmeter method is used in a three phase sysstem to measure the true power without regard to the balance ie. It can be used to measure both balanced loads and unbalanced loads.The three phase power could be measured using single phase wattmeters in each loads of the system. But using three wattmeters is quite unnecessary as we can measure it by using only two wattmeters.The three phase power could be measued by using single phase wattmeters , haing a current coil in one line and a potential coil connected between the line and some arbitrary common junction point. If that arbitrary common point is chosen on one of the three lines, then the wattmeter connected to that line will indicate zero power because it's potential coil has no voltage across it. hence, that wattmeter may be eliminated, and the three phase power can be determined by means of only two single phase wattmeters.
What is effect of power factor on the readings of wattmeter?
If you are asking whether power-factor improvement has any effect on a wattmeter reading, then the answer is no, it doesn't. Improving the power factor of a load has absolutely no effect on the power of the load, but it can act to reduce the value of the load current.
