John Miklavcic, Rockwell Automation

Our January 16 meeting concerned the benefits and savings accrued from switching from fixed speed fans and pumps to variable speed drives (VFDs). John Miklavcic, Power Control Area Manager for Rockwell Automation, made the presentation. The meeting took place in the offices of Rumsey Electric Automation Solutions in Conshohocken and attracted about fifteen members and guests.

Miklavcic began by noting that in North America, motors constituted the largest consumers of energy in the industrial sector at 63%. Pumps and fans account for about half of this figure. Pumps alone represent 20% of electrical demand globally. As an example, he said, a 100 HP induction motor running two shifts a day costs a company $36,185 annually at a utility rate of $.08 per kilowatt hour. Anything that can be done to increase the efficiency of motors represents pure profit.

Variable speed drives, said Miklavcic, effectively increase this efficiency. VFDs adjust the speed necessary to meet the requirements of the application. If the application requires just 60% of the drive’s maximum speed, then the horsepower required drops to 22%. He continued by citing the case of the 100 HP motor mentioned earlier. Running at 60% of maximum speed, the yearly cost would drop from $36,185 to $7,961–a savings of $28,224.

Miklavcic continued with VFD calculations of energy savings for representative industrial examples. He noted that many utilities offer rebates for purchases of VFDs as incentives for companies to switch from fixed speed motors. He said that the typical payback time for such purchases was less than two years.

For a copy of the Miklavcic presentation in PDF format click here.