The power system for this major NYC bank providing nationwide credit card and other financial transactions appeared to be performing satisfactorily. Fortunately, the proactive monitoring approach employed in this facility identified a power quality trend that could have caused a catastrophic failure.
Non-symmetrical waveforms rich with even order harmonics indicate a problem in the power system. The problem was identified as a partial rectification by the UPS of the AC power instead of a full rectification. The UPS would have failed if the system had switched over.
While the bank did not experience any overt power quality problems, monitoring at the input and output of three separate UPS systems identified non-symmetrical waveforms and a trended increased in even-order harmonics. Since this harmonic pattern is indicative of an improperly operated power system, a spectrum analysis was performed. That analysis identified a partial rectification where a full rectification of the AC power should have occurred. Left alone, the UPS would have failed to perform. The UPS maintenance team was quickly brought in to repair the problem and ensure high 9’s reliability.