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The terms you are looking for are 'dynamometer' (no hyphen!) or 'electrodynamic' instrument. These terms describe an instrument movement, where the torque applied to the pointer results from the interaction of magnetic fields produced by fixed and moving coils. In the case of a wattmeter, the fixed coil is the current coil which is connected in series with the load, and the moving coil is the voltage coil which is connected in parallel with the load.
A dynamometer type instrument differs from a moving-coil instrument, such as an ammeter or a voltmeter, in which the torque applied to the pointer is the result of the interaction between the magnetic fields produced by the moving coil and a permanent magnet.
For three-phase power measurements, it is possible to use just two wattmeters in a configuration called the 'two wattmeter method'.
What else can I help you with?
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.
Does a wattmeter indicate real or apparent power?
As its name implies, a 'wattmeter' measures 'real' or 'true power'. It does this by measuring the supply voltage and the in-phase component of the load current.
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 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
Is it possible to measure power factor of the balanced three-phase load by two-wattmeter method?
yes.
Explain the Two wattmeter method of power measurement in a 3 phase circuit?
A single wattmeter can measure power due to one phase only. But circuit arrangements , popularly called: 1) 2-wattmeter method (requiring two wattmeters) 2)3-wattmeter method (requiring 3 wattmeters) can be used for measuring power inn 3-phase circuit. The details of these method can be found in any standard book on electrical engineering.
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.
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 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.
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.
Do you need only a watt-meter in a three phase power?
To measure the power of a three-phase load, you need to use one less wattmeter than there are conductors supplying that load.
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
