how to calculate the capacitor rating for improving power
factor
Answers were Sorted based on User's Feedback
Answer / r n seth
capacitor required is too be calculated from required power
factor to desired power factor.the formula is-
Req. Cap in KVAr= Tr. MVA* PF( tan cos-1(existinf PF- tan
cos-1(desired PF))
Is This Answer Correct ? | 21 Yes | 4 No |
Answer / engr. tariq
Formula :
C = P (tan|old - tan| new) divided by Omega (w) and then
divided by Voltage (RMS) or Vrms.
theta (|) can be calculated by knowing cos theta OR power
factor. Example PF is 0.77 then Cos theta = 0.77 and Cos
inverse (0.77) = 39.646 = Theta OLD. Now
Now if i want to improve PF to 0.9 then theta = Cos inverse
0.99 = 25.841 = theta New.
After calculating theta put it in the Given formula to
calculate Capacitance required.
Is This Answer Correct ? | 11 Yes | 1 No |
Answer / engbri
Another way i use is to take the PF and turn it into an
angular measurement in degrees. using j notation and the
magnitude of the wave you can calculate the size of
resistance, or real component and the size of the inductive
reactance or the -J component. Do this with a simple Polar
to rectangular conversion, if you cant your calculator
probably can. Then making the capacitive reactance equal to
the inductive reactance cancels it as they are oposites.
Then using the formula Xc = 1/2piFc transpose for c which
gives c =1/2piFXc. however as the cpacitor is taken as
ideal and with no resistive component this will never
reduce the PF to zero.
Is This Answer Correct ? | 5 Yes | 0 No |
Answer / charu gupta
kVAr Rating = kW(tan A - tan B)
Where kVAr rating is the size of the capacitor needed,kW is
the average power drawn, tan A is the trigonometric ratio
for the present power facotr, and tan B is the
trigonometric ratio for the desired PF
Is This Answer Correct ? | 6 Yes | 1 No |
Answer / engr. tariq
Please note that in answer # 5 omega (w) is equal to the
frequency of the system.
Is This Answer Correct ? | 4 Yes | 0 No |
Answer / salman
to find above answer so we can directly go through
contract technical book this easiest way.
Is This Answer Correct ? | 2 Yes | 2 No |
Answer / pavan vyas
as a thumb rule it should be 1/3 of load kw & theoretically
we can select from the chart
Is This Answer Correct ? | 8 Yes | 13 No |
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