by adding the opposite type of reactance. as motors are a common industrial load and their reactance is inductive, add capacitive reactance.
Power factor is an AC only term, and has no meaning for DC.
Usually capacitors in an AC system are there to improve the power factor. Transformers are used to increase or decrease line voltages.
In an AC system power is equal to Voltage x Current x Power factor. Power factor is not constant and depends on the type of the load. Ideal value of the Power factor is 1, where as practically remains less then 1.
Per factor is 1 when reactive power is zero.
AC-1This applies to all AC devices (Resistive loads) with a power factor of at least power factor of 0.95 AC-3This applies to AC Inductive loads. Like squirrel cage motors.
No difference in case of DC. In case of AC Watt refers to Power which includes the factor of power factor. VA does not include power factor.
The ratio of true power (measured in watts) to apparent power (measured in volt-amperes) in an AC circuit is known as the power factor. It is a dimensionless number that ranges from 0 to 1 and indicates how effectively electrical power is being converted into useful work output. A power factor of 1 (or 100%) means all the power is being effectively converted to work, while a lower power factor indicates inefficiencies in the system. The relationship can be expressed mathematically as: Power Factor (PF) = True Power (P) / Apparent Power (S).
Power Factor is one of most significant parameter in calculating AC Power. As we know it is cosine of angle between AC Voltage and Current it comes in picture while calculating power in AC circuits Power In AC (P) = Voltage (V) X Current (V) X Power Factor Let us take an example of Power with Power factor and without power factor for same circuit. Let Us assume V = 125 Volts I = 1 Amp Power Factor = 1 Then P = 125X1X1= 125 Watts But for any circuit when Power factor is below 1, to execute same power, Circuit has to draw more current. for example P = 125X 1.25 X 0.8 = 125 Watts In first example power factor of the circuit was unity = 1 and in that condition current of the circuit was 1 amp whereas in second example power factor of the circuit is 0.8 due to which current of the circuit increases to 1.25 amp to execute the same power. Now due to increase in current of the circuit many factors are affected like heat loss, Conductor's specification , Class of insulation etc. Thus it can be concluded after going through above explanation that power factor play a significant role in AC power calculation as well as in actual practices.
because of high resistance in the load.
The firing delay angle is the point in the AC cycle at which a thyristor starts conducting. By adjusting this angle, the power factor of the system can be controlled as it affects the balance between real power and reactive power. A smaller firing delay angle can improve the power factor by reducing the phase difference between voltage and current.
With a dc system the kW are always equal to the kV times the amps. It's only with ac that the kW are usually less than the kVA by a factor called the power factor.
Rectifier