Answer Posted / ganeesh jain
We know that reactive loads such as inductors and capacitors
dissipate zero power, yet the fact that they drop voltage
and draw current gives the deceptive impression that they
actually do dissipate power. This “phantom power” is called
reactive power, and it is measured in a unit called
Volt-Amps-Reactive (VAR), rather than watts. The
mathematical symbol for reactive power is (unfortunately)
the capital letter Q. The actual amount of power being used,
or dissipated, in a circuit is called true power, and it is
measured in watts (symbolized by the capital letter P, as
always). The combination of reactive power and true power is
called apparent power, and it is the product of a circuit's
voltage and current, without reference to phase angle.
Apparent power is measured in the unit of Volt-Amps (VA) and
is symbolized by the capital letter S.
As a rule, true power is a function of a circuit's
dissipative elements, usually resistances (R). Reactive
power is a function of a circuit's reactance (X). Apparent
power is a function of a circuit's total impedance (Z).
Since we're dealing with scalar quantities for power
calculation, any complex starting quantities such as
voltage, current, and impedance must be represented by their
polar magnitudes, not by real or imaginary rectangular
components. For instance, if I'm calculating true power from
current and resistance, I must use the polar magnitude for
current, and not merely the “real” or “imaginary” portion of
the current. If I'm calculating apparent power from voltage
and impedance, both of these formerly complex quantities
must be reduced to their polar magnitudes for the scalar
arithmetic.
REVIEW:
Power dissipated by a load is referred to as true power.
True power is symbolized by the letter P and is measured in
the unit of Watts (W).
Power merely absorbed and returned in load due to its
reactive properties is referred to as reactive power.
Reactive power is symbolized by the letter Q and is measured
in the unit of Volt-Amps-Reactive (VAR).
Total power in an AC circuit, both dissipated and
absorbed/returned is referred to as apparent power. Apparent
power is symbolized by the letter S and is measured in the
unit of Volt-Amps (VA).
These three types of power are trigonometrically related to
one another. In a right triangle, P = adjacent length, Q =
opposite length, and S = hypotenuse length. The opposite
angle is equal to the circuit's impedance (Z) phase angle.
Is This Answer Correct ? | 4 Yes | 0 No |
Post New Answer View All Answers
why asa method ZPF method is more accurate than ASA method?
How to calculate multiplication factor in kva example 500kva ans pls ?
Why do we avoid electrical conduits in floors at apartments?
Any Electrical Engineering jobs?Please refer for interviews. Thank you
How can we calculate cable size in Low voltage & high voltage
What are the necessary components of the feedback control system?
May I know how much values to be set for earth fault, over current and short circuit values at 11kv side? I have 11kv van 1250amps rating. Present it's taking load 80amps?
HOW MUCH CURRENT DOES SYNCHRONOUS MOTOR TAKES AT SYNCHRONOUS SPEED IN NO LOAD CONDITION ?
what is the use of expulsition protective gap in 11Kv line.
How line capacitance & line inductance varies with increase in height tower.
What is boucholz relay and the significance of it in to the trformer?
Discuss about gear cutting machines.
What is the ideal position cooling fan inside the dc motor?
there are cam operated switches - why we call cam operated , What is cam ?
1) why a dg set shows variation of power factor and load when synchronised with other dgs? 2)Why the load sharing is not become equal in all dgs?. 3)When a dg set will not run on auto start?