Help needed on SINGLE PHASE A.C CIRCUIT QUESTION

Mariner SG

Q : A coil having a resistance of 20 ohms takes 950W from a 230V, 50Hz supply. Calculate
a.) The inductance and the power factor of the coil
b.) The reactive volt-amperes

* can someone explain what is
- power factor
- volt amperes

thxs Very Happy

strikefreedom SG

Power Factor: The fraction of power actually used by a customer's electrical equipment compared to the total apparent power supplied, usually expressed as a percentage. A power factor indicates how far a customer's electrical equipment causes the electric current delivered at the customer's site to be out of phase with the voltage. (from google)

Volt Ampere refer to the apparent power of the system which is represented by the letter S.

P=VI cosX X is ur angle and is present due to the inductance/capacitance
Q=VI sinX Q is ur reactive power
S^2 = P^2 + Q^2

[email protected] SG

doing electrical engineering? Laughing

power factor seems to be another word for the efficiency of the machine at using the power?

798 SG

Assume:
1) RL circuit connected in series
2) Circuit in steady-state

Under steady-state,
Current, I = E/R = 230V/20ohms = ? A
Apparent Power, S = EI = 230 * ? = ?? VA

a) Power Factor, cos theta or pf = P/S = 950/?? = ??? (lag) (because circuit is inductive)

Reactive Power, Q = sqrt(S^2 - P^2) = sqrt(???^2 - 950^2) = ???? VAr (lag)
(Q in positive because inductive)

back to question a)
Q = I^2 * X (X is reactance of inductance)
X = Q / (I^2) = ???? / (?^2) = ????? ohms

Inductance, L = X / (2 * pi * frequency) = ????? / (2 * pi * 50) = ?????? H

b) Ans in part a. = ???? VAr (lag)

Explanation:

go to this site:
http://www.ibiblio.org/obp/electricCircuits/AC/AC_11.html#xtocid181751

Bryan^ SG

Haha…EE is the nitemare…To solve ur ans to any question Find all the formulas…See wad value is given and see which formula got tt value den use it….

shade343 SG

Although I not learning engineering, I dont know why my course got teach me this also. Laughing I lifting this from my notes my lecturer give me,

Power Factor
Apparent Power consists of True Power and Reactive Power.

The presence of the reactive power component in a system causes :-
- voltage and current to be out of phase;
- some of the energy supplied as apparent power is lost in heating the circuit.

Power factor (P.F) determines how much true power is transferred to the load and can be calculated using the formulae P.F = True Power / Apparent Power.

The PF range of value is between 0-1

[email protected] SG

anything that includes maths is a nightmare

Xcert SG

where got so simple one? Laughing Mr. Green