Ahorro Energia

Energy Saving systems for Induction motors.
Are they a sham? Do they work?
There seems to be a resurgence in interest in the Nola energy saving algorithm for induction motors, with a number of manufacturers beginning to market “new” and “improved” versions of this technology.
The technology was originally proposed and developed by Frank Nola of NASA in the mid to late 70s as a means ofreducing energy wastage on small single phase induction motors. From the initial NASA developments, we saw a number of manufacturers world wide gaining manufacturing rights and marketing the technology in various forms. Difficulties were experienced in the early days in applying this technology to three phase motors in a fashion that it would perform with stability and reliability. Many patentapplications were made in the early 80s covering variations on the technology as it could be applied to the three phase applications. An early application by Rutherford and Empson was successful in both operating as specified and in being granted letters patent. Many of the other early three phase patent applications were purely speculative and could not possibly achieve the desired results. The concept ofenergy saving has always been an attention grabber, especially when the promised savings are high and the potential for a reduction in running costs appears high. The initial introduction of this technology was a marketing person’s dream, and some very extensive marketing plans were implemented in the early 80’s. Unfortunately, the marketing was based on the results achieved with very smallmachines, and expectations were high because of the results so achieved. There were many promises made to prospective users based on extrapolated data which was not field verified at an early stage, and could not be realized in real applications. I recently reviewed some promotional material which disturbed me in that exactly the same misrepresentation as was common from some suppliers of the technologyin the early 80’s was again the foundation for a major promotion of this concept. As we experienced in the early eighties when we were manufacturing similar products, there appear to be many misconceptions about the performance of induction motors and many claims are based on the presumption that the induction motor at less than full load, is an inherently inefficient device. We withdrew frompromoting this type of device as a result of expectations in the market place that resulted from overzealous marketing with totally unrealistic claims which could not be achieved without inventing perpetual motion. - I recall a refrigeration engineer who had been promised a 50% energy saving on his 50KW refrigeration units which were constantly running at about 50% load. He had tried numerous unitsto no avail, and eventually approached me on a recommendation. I asked him for the efficiency of the motors at this load and he found that it was about 87%. As he immediately began to see, there was no way that he could save 50% of the energy consumed by the motor. To do so would require a motor efficiency of over 100% which is just not possible with an induction motor and today's technology. Thereis no doubt that under the right conditions, the technology as proposed by Frank Nola and the many variants thereof, can reduce the energy drawn by an induction motor, and thereby achieve some benefit. The problem is that as the result of limited technical understanding of the induction motor and it’s characteristics, erroneous claims are being made by extrapolation of results achieved with smallmotors. Worked examples often show flawed methodology in making power measurements in three phase three wire installations.

1. The Technology.
The basic algorithm is proposed by Frank Nola 20 years ago is to monitor the power factor of the motor, and to reduce the voltage when the power factor is dropping in a manner as to increase the power factor. There is a correlation between the power...