How the power factor is caused.? what is the effects? what is kvar? kw? kva?

Question

Whether power factor arise only in 3phase ac or also in 1phase ac?
What is LEAD LAG UNITY?

what is the difference between kw and kva ?

Answer 1

The website book section on AC circuits linked below is probably your best bet to get a full understanding of this topic. Click on the power factor chapter; it is pretty good.

Nevertheless, my quick answers to your questions:

power factor arise only in 3phase?
** Nope. It must be considered in both single and multiple phase AC circuits

difference between kW and kVA?
** One is the unit for real power (kilo Watts) and the other is the unit for apparent power (kilo Volt-Amperes). kVAR (kilo Volt-Amperes Reactive) is the unit for reactive power (basically power that is stored and released in inductive/capacitive loads). Real power and reactive power sum up to equal apparent power (see the triangle diagram in the linked page).

How is the power factor caused? What is the effects?
** The power factor is the cosine of the impedance angle of your load (or the apparent power angle of the load, same thing). Power factor varies between zero and one. Where one indicates all real power (resistive impedance) and zero indicates all reactive power (inductive or capacitive impedance). In between zero/one is a combination between the two. Generally, we like to have a power factor near one; otherwise supplying power to large reactance loads can be wasteful and can lead to unsatisfactory voltage drops at the load.

power_factor = cos(voltage_angle - current angle) = cos(impedance_angle)

What is lead/lag/unity?
** unity => pf = 1 (all resistive load, voltage and current in phase)
** lagging => pf between 0 and 1 (corresponds to inductance in the load, current angle LESS than voltage angle)
** leading => pf between 0 and 1 (corresponds to capacitance in the load, current angle GREATER than voltage angle)

We need the lead/lag distinction in power factor, otherwise we don't have any idea if we are talking about an inductive/capacitive load.

Hope that helps.

Answer 2

Power factor (Cos(pi)) is due to the phase shift between voltage and current. This phase shift is due to inductive(XL) and capacitive (Xc) effect. The the inductive effect is greater it causes the lagging effect and when the capacitive effect is larger it causes a leading power factor. They determine the transmission efficiency and losses. Kvar gives the power developed due to inductive reactance.Kva is apparent power and Kw is the active power which gives the power dissipated in the circuit.

All a.c. Circuits has the effect of power factor due to the inductive effect (the capacitive effect is rare and minimum if present)

Answer 3

power factor, to explain in short is the latency of power. Most 3 phrase power supply have latency of 0.8 .. which is the power factor.. For instance, 20 kva .. converted to KW simply , 20 X 0.8 .. and give u the KW.
Normally for single phrase, the power factor is 1. No latency ..
WHen power factor is 0.8, only 80% of the power output is effective. the rest is wasted as heat energy

Answer 4

Kvar on my language means Error