Power Factor Capacitor Failures
Power Factor Capacitor Failures
(OP)
I have little to no expertise in this area and was hoping I could receive some guidance. I have seached the forum regarding PF correction capacitors and have not came up with any solutions.
I have a customer that has some power factor correction capacitors across the feed of two air handeling units. The customer says that he recently lost some capacitors (I'm thinking due to age)and would like us to do a power quality survey. From what I am told these capacitors are are across the line at all times (wether or not the air handelers are running).
Can someone please give me some direction as to what possible problem causing areas, I should be looking for after we have collected data for a few days.
Any pointers will be greatly appreciated.
Thank you in advancne.
I have a customer that has some power factor correction capacitors across the feed of two air handeling units. The customer says that he recently lost some capacitors (I'm thinking due to age)and would like us to do a power quality survey. From what I am told these capacitors are are across the line at all times (wether or not the air handelers are running).
Can someone please give me some direction as to what possible problem causing areas, I should be looking for after we have collected data for a few days.
Any pointers will be greatly appreciated.
Thank you in advancne.






RE: Power Factor Capacitor Failures
2.) If caps are floating are you going into a lead when the air handlers aren't running and maybe causing high voltage condition. If the caps are applied specifically for the air handlers the should be switched with the motors.
RE: Power Factor Capacitor Failures
RE: Power Factor Capacitor Failures
Distorted local voltage and current from harmonics come to mind. Until more sophisticated PQ instruments can be obtained, comparison in readings of known-accurate true-RMS and average-responding meters may be somewhat revealing. Alternately, waveform crest factor deviating from 1.4 through ratio of peak and RMS readings may be a good initial indicator.
RE: Power Factor Capacitor Failures
RE: Power Factor Capacitor Failures
The capacitors in this installation are approximately 10 to 15 years of age. I am planning to check the values of the capacitors prior to monitoring to rule out any "bad" caps in the bank.
RE: Power Factor Capacitor Failures
You may want to check the power factoro on line side of VFD when PFC is disconnected and AHU running. Chances are that ,depending on the VFD's , the input power factor is well above 0.9 (.94, .95 etc). The 'additional' PFC are redundant causing leading pf and over voltages etc.
I would remove the PFC's altoghether.
RE: Power Factor Capacitor Failures
RE: Power Factor Capacitor Failures
regards,
Danny
RE: Power Factor Capacitor Failures