I have been contemplating on this subject for quite some time and am unable to decide this as there are varying opinion on this topic which makes even more tougher to conclude. Some high power pro amps using SMPS ckt already have some PFC circuits inbuilt into their amplifiers. Also its mandatory to have PFC for high power devices. But home audio amplifiers which consumes lesser than 100Watts do not fall in the ambit and there are seldom any penalty for lower PF.
An ideal PF for a resistive load is 1.0 and for inductive and capacitive load if is less than one. Most audio amplifiers provide a non-linear load to the AC grid. I measured the PF in my amplifier load and it varies from 0.6 to 0.65 depending upon the time of measurement. I measured using the 3 voltmeter method as per this link http://www.giangrandi.ch/electronics/cosphi/cosphi.shtml
I was able to calculate a PFC capacitor directly connected across the AC line to be around 6.2uF. Adding this capacitor brings the PF back to around 0.95. This will bring the current and voltage back in sync. The capacitor can also help in reducing odd harmonics in the AC line and do some kind of line current clean-up too. The capacitor will be connected in the same AC powerline and will be switched on / off along with the amplifier.
I am not looking at power savings or energy bill reduction, but wanted to check if bringing the current and voltage to some sync, will this reduce some heat in my transformer and will my PSU run a little cooler as i am actually reducing the I2R losses in the transformer lamination. Also odd harmonics above the fundamental (50Hz) will be filtered by the inductive transformer and the capacitor by forming a Low Pass filter..
Please suggest your opinions as this could also be a wasted exercise by me - but nothing to loose in checking out. I may plan to check the PF again after adding the capacitor to see if did any magic.
An ideal PF for a resistive load is 1.0 and for inductive and capacitive load if is less than one. Most audio amplifiers provide a non-linear load to the AC grid. I measured the PF in my amplifier load and it varies from 0.6 to 0.65 depending upon the time of measurement. I measured using the 3 voltmeter method as per this link http://www.giangrandi.ch/electronics/cosphi/cosphi.shtml
I was able to calculate a PFC capacitor directly connected across the AC line to be around 6.2uF. Adding this capacitor brings the PF back to around 0.95. This will bring the current and voltage back in sync. The capacitor can also help in reducing odd harmonics in the AC line and do some kind of line current clean-up too. The capacitor will be connected in the same AC powerline and will be switched on / off along with the amplifier.
I am not looking at power savings or energy bill reduction, but wanted to check if bringing the current and voltage to some sync, will this reduce some heat in my transformer and will my PSU run a little cooler as i am actually reducing the I2R losses in the transformer lamination. Also odd harmonics above the fundamental (50Hz) will be filtered by the inductive transformer and the capacitor by forming a Low Pass filter..
Please suggest your opinions as this could also be a wasted exercise by me - but nothing to loose in checking out. I may plan to check the PF again after adding the capacitor to see if did any magic.