Dan Noël, Intricate Power Quality Problem Solver

Dan's wealth of experience in three phase power systems, high integrity and exceptional analytical abilities uniquely qualify him to assist you in your questions, uncertainties and problems related to the availability of power at the input of your critical equipment.

& Leadership


DC Power






From 1991 to 2004, while working for MGE UPS Systems, Dan promptly diagnosed and solved numerous seemingly intractable power quality problems experienced by large UPS system users...

  • Dan recognized over a few hours of improvised on-site experiments the cause of spurious "excessive phase, uninterrupted transfer prohibited" alarms that had upset user yet eluded other experts for several months: a generator's frequency was slightly wobbling, not enough to be recognized by ear or to be out of spec, but just enough to fool the UPS's PLL into occasionally bringing the phase error out of tolerance and triggering the alarm.
  • A user complained that a UPS was disturbing an unusual load, composed of a rectifier and a low pass, low loss filter, followed by DC circuits.  The user traced the disturbance to a very light random low frequency ripple on the DC supply.  Dan quickly diagnosed that the problem was caused by some imperfections in the inverter's PWM control, made recommendations to smooth it out and directed a rather complex redesign; the first breadboard happened to address the problem.
  • A custom-made parallel UPS system would produce a thumping noise in a transformer during uninterrupted transfer from bypass to inverter.  Dan determined, through a thorough design review from the power components down to a PAL and without any experiment, that the phenomenon had to involve a break during the transfer and was only a symptom of a serious design weakness.  Dan developed a patch that alleviated the problem and recommended to discontinue this type of systems.
  • Dan spearheaded efforts to understand an epidemic of sporadic inverter and charger shut downs in the field with no understandable reason; investigation was thwarted when it was discovered that the major complainant had abused the UPS on several occasions; after Dan insisted that the behavior of some cards whose design was controlled overseas failed to conform to their specification in one important detail, investigations uncovered an occasional timing error on a microcomputer that caused the occasional problems on 60 Hz applications only. Resolution was straightforward.
  • A highly complex 3 MVA UPS installation dumped partial load; Dan quickly recognized that the UPS suffered internal failures, yet had put out alarms that gave the user proper clues to take preventative measures to avoid the load dump. Dan also analyzed the reason why several UPS modules spuriously tripped their battery breakers as they dumped the load.
  • Dan was the point-person in recognizing the interaction between an inverter and some inductive loads as due to the limitations of the design of the system that controlled the flux bias in the inverter transformer.
  • After spending a week in Excel, Dan predicted operational limitations of an STS controller that were not seen by a dedicated pre-development team using simulation tools; qualification tests confirmed the limitations a year later.
In the doubt... ...contact Dan before trouble strikes.
If trouble has stricken... ...contact Dan to understand how and why.
If you understand how and why... ...contact Dan to better assess remedial action.