Hi
we have 500KVA transformer 11KV/433V delta star 4% Impedance and 110 KW 3Phase induction motor we have facing the power factor problem for motor we put 45 KVAr capacitor and for transformer we put 10 KVAr capacitor than the power factor comes to 0.95 last month suddenly the power factor comes to 0.88 we checked all the capacitor condition found OK motor current also found normal motor running time is 8 hours/day when ever motor running capacitor switch on automatically
any one give the suggestion for improve power factor
g senthil
Assuming you are running at full load and don't have any other loads connected, I think the power factor reading of 0.88 is possible. I have checked through the calculations and if the motor is running at 0.7 power factor without correction, than the 55 kVAr of correction will make the overall power factor 0.88.
As a suggestion, you could switch out the correction and see what power factor the motor is running at.
yes we are running the motor at full load for 55 KVAr of correction power factor is 0.998 after the motor stopped there is no load condition the power factor is 0.365 for the 500 KVAr transformer we put one 10 KVAr capacitor but the power factor does not improve for that we checked this problem the power factor is not stable at the time of no-load
connected load details
we have HT supply 11 KV 500 KVA Transformer Delta-Star connection
Voltage - 11KV/433Volt
Percentage of Impedance 4%
110 KW motor 415V 3 Phase Running 8 Hours/Day
5 KVA UPS 230 Volts Single Phase Continous on 24 Hours
2 KVA Invertor 230 Volts Single Phase Continous on 24 Hours
2.2 KW AC machine 230 Volts single Phase Continous on 24 Hours
Lighting load of 2 KW Single Phase 12 Hours working/Day
Metering was fixed at HT supply
for this type how can we compenstate with capacitor for Improve the Power Factor
The trans former Details given below is Connected for this transformer how to calculate the capacitor rating in idel condition
already we connected 10 KVAr capacitor for compensation of power factor but the power factor is fluctuating to 0.5 to 0.93
Transformer Rating - 500KVA
Volts HV/LV - 11000/433 V
Current HV/LV - 26.24/666.69 A
Vector group DYN-11
please give me the suggestion for improve the power factor and calculating method,formula
Thanking you
Regards
G.Senthilkumar
Problems like this are always difficult to solve if you are not on site. If the power factor is fluctuating as you say, my guess would be that the 110 kW motor is experiencing varying load conditions. I would first try to investigate this and either confirm the assumption or rule it out.
Power factor is fluctuating in ideal condition only when ever 110 KW motor loaded power factor is constant as 0.98
Have you done any more research or found the answer to the problem yet.
Dear G Senthil.. I advice you search Siemensepcos website to get some basic idea.. There is no perfect solution for arriving at the perfect KVAR of capacitor. for highly fluctuating and harmonic loads thyristor based Detuned filter capacitor with APFC relay should be used. For selecting the filter you have to conduct harmonic analysis. for low fluctuations. you can design contactor based APFC panel with manual facility for switching capacitors.
Regards, Have a nice day