Home › Electrical Engineering Forum › General Discussion › Low power factor in arc furnace operation › Re: Low power factor in arc furnace operation

Low power factor in arc furnace operation

1. the power meter installed by authority is to read a cumulative kWh, kVARh and KVAh from various appliances.

2. take a sample of reading of power meter as mentioned below:

Date: Time: kWh kVARh kVAh

25.09.2013 12:00:00 X Y Z

26.09.2013 12:00:00 A B C

Difference: 1 day 24 hour (X-A) (Y-B) (Z-C)

tan(Φi) = (Y-B)/(X-A) = R i.e. assume R = 0.7

Φi = arctan[(R)] = 34.99

cos(Φi) = cos(34.99) = 0.82

value of capacitor bank, kVAR = kW [tan(Φi) – tan(Φf)]

assume final cos(Φf) = 0.96,

Φf = arcos(0.96) = 16.26

therefore tan(Φf) = tan(16.26) = 0.292

The value of capacitor bank, KVArRh = kWh [tan(Φi) – tan(Φf)]

= (X-A)*[0.7 – 0.292)

= (X-A)*0.408

=0.408(X-A)

the value of capacitor bank, kVAR = kVARh/(24 houurs)

=0.408*(X-A)/24 = 4*416.67 = 1666.68

therefore (X-A) = 4*416.67*24/0.408

= 98040 kW

therefore, the difference in (X-A) in terms of kWh = 98040*24 = 2352960 kWh

Therefore, I suggested that reading of kWh, kVARh shall be take every hours and stated date and time taken of reading.