lagging power factor

Question five , if you aren't going to do your own homework, why don't you use the search box, on the right-hand side of the page to find your answers.

I liked that answer CJ. In the analogous manner you explained it, you did not directly fill in the person's homework, yet gave enough that if they want to think about it they certainly can get what they need from it.

CJMcGill

Good answer. Well described in simple language for a layman to understand the concept . Really you are a good teacher, my hats off to you .

Remember the relationship between current phase and voltage phase in a capacitive or inductive circuit by using the phrase ELI the ICE man. Voltage leads current in an inductive circuit and conversely, current leads voltage in a capacitive circuit.

Hello 1234,

There are three "different kinds of power" in AC circuits, three values that are called power, but strictly speaking only the True Power (watts) is a measure of energy converted into work, the definition of power. It is calculated by multiplying the volts x amps in the circuit component where the voltage and current are in phase, the resistor, which is the only component in the circuit that can convert energy.

Many industrial facilities electrical systems operate at a low power factor because the majority of their load consists of motors. Motor loads require Reactive Power (vars), often referred to as magnetizing vars because it sustains the motor's magnetic field. This means some of the current that the motor draws is "out-of-phase" current(shown in blue). This is in addition to the "in-phase" current (shown in red), that delivers the true power that represents energy converted into mechanical motion.
Reactive power is calculated by multiplying the volts x amps in the circuit component where the voltage and current are out-of-phase, the coil, which as a circuit component, can only store energy, not convert it.

Apparent Power (volt-amps) is a measure of what the actual power would be if the line voltage and current were perfectly in phase. It is calculated by multiplying the line (supply) volts x amps, or by adding the watts and vars vectorially.

The term Power Factor actually means - the percentage of the apparent power that is true power. It can be calculated by a number of methods.
PF = W/VA

You can also think of it as - what percentage of the total current is in-phase current?
PF = In-phase current/total current

The reactive "power" is not a useful energy conversion. It represents the energy that flows in to the motor to build up the magnetic field each cycle, and when the field collapses one half cycle later this energy is regenerated back to the power plant.
This represents current (out of phase) flowing in the service equipment, transformers, and circuit wiring, that does no useful work. If a device were connected to the circuit that could intercept and store this energy, and return it to the motor winding for the next magnetic field buildup, instead of requiring it to come from the power plant each cycle, the motor could do it's job with less current.
A capacitor can perform this function when connected in parallel with the motor, and this is called power factor correction.
With power factor correction the motor still draws the magnetizing (out of phase) current, however it now comes from the capacitor. Power factor correction is normally only installed in large facilities where most of the load is motors. Individual capacitors can be installed at each motor or a large capacitor bank can serve a feeder or motor control center. The capacitor bank ratings are normally calculated in Kilovars (kvar)."

Now that i have bored you....let us see a more interesting analogy for power factor...

Think of:
KVA as the size of a beer mug.
KW as the amount of beer in the mug.
KVAR as the amount of foam in the mug.

PF, then is the percentage of beer in the mug.

A bad power factor is too much foam and not enough beer. While, an ideal PF would be lot's of beer with a small "head" on it.

Cheers and Beerchugs..

I have been wondering what is happening with 1234, and whether the highly technical or the pictorial analogies are most useful to him. I try to be careful to encourage study and research for one who is obviously a student.

We have yet to discuss the implications of PF on transmission as he requested, which involves an understanding of resonance.

You are the first person I have seen on this forum that linked the resistive component to the transfer of the energy, which leads to a greater understanding of this subject.

I noted references (shown in red) and (shown in blue); were there drawings that did not come through as planned?

CJ

I had thought to ask this a while back, but I considered the question for some time first.

I am tempted to pose challenge questions of various sorts for everyones edification, but since I am fairly new to this forum I am being careful not to assume the subject matter has not already been covered in a discussion thread that the heading would not reveal etc.

As for this specific subject, I have a question that relates to how capacitance and inductance work together in factual terms, not equational terms.

The question I am posing to you based on your explanation is: Can current flow two directions in one circuit at the same time. To be specific, I am addressing the fact that current is part of the kW and also part of the kVAR equation. They theoretically flow 90 electrical degrees apart. At some points in the sine wave of each they are going opposite directions. So my question is, at these times, do the 2 currents flow in opposite directions in the circuit?

Please don't hesitate to offer suggestions as to the form or substance as to how this question has been posed, since I trust you to be clear on this from what I have seen you post. Thanks in advance, CJM

An editing note: I meant this to be marked "off topic" but am unable to correct this oversight after once posted apparently, sorry.

Dear Mr.1234,

What is your background of education.? The answer is available in the 1st year Elec.Engg. course.

The answer can be very simple to high order Mathematics Equations involving Integration and Laplace Transform.

DHAYANANDHAN.S