The Power of The F word – a history of drives

Don’t Panic… I’m talking about FREQUENCY.
Or to be more specific the history of the Variable Frequency Drive. Also termed adjustable-frequency drive, variable-speed drive, AC drive, micro drive, inverter drive or in its simplest term a Drive.

When Tesla first introduced the 3-phase alternating current (AC) induction motor in 1888, he knew that his invention was more efficient and reliable than Edison’s direct current (DC) motor. However, AC motor speed control requires either varying the magnetic flux or changing the number of poles on the motor. Even decades after the induction motor gained widespread use, changing the frequency for speed control remained an extremely difficult task — and the physical construction of the motor prevented manufacturers from creating motors with more than two speeds.

Analogue to Digital to our Weatherproof Rental VSDs

As a result, DC motors were necessary where accurate speed control and significant power output were required. In contrast to AC motor speed control requirements, DC motor speed control was achieved by inserting a rheostat into the low-power DC field circuit, which was feasible with available technology. These simple motor controls varied the speed and torque and were the most economical way to do so for a number of decades.

By the 1980s, AC motor drive technology became reliable and inexpensive enough to compete with traditional DC motor control. These AC drives accurately controlled the speed of standard AC induction or synchronous motors and have today become the industry norm. But this was not always the case the introduction of this new AC motor controller brought major disruption to an old and sleepy industry still focused on high maintenance, low efficiency DC frequency control technology, and many benefits to Todays Engineers and Industry. It was a game changer!

How long before Space Travel is the Norm?

You can disrupt an industry by innovation or great service in an industry renowned for bad, the classic example of this is Richard Branson and Virgin Atlantic. (If you don’t remember British Airways 20-30 years ago, it was not
pleasant experience). He is at again now with his Virgin Galactic a commercial spaceflight company within the Virgin Group that is developing commercial spacecraft and aims to provide suborbital spaceflights to space tourists,
innovation through technology at its best.

Quantum Controls have been an ABB Drives Service Provider since 1992 and are the Official Drives Service Partner for Danfoss, Schneider, Vacon, Mitsubishi, Controls Techniques as well as been fully trained on Siemens and SEW Drive Products. So one company that can look after all of your drive needs no matter drive make, type and power rating on your site.

So, with Variable Speed Drives now being the accepted technology for motor starting, how long will it be before we have space travel available for everyone, probably not in my life time but maybe our children’s.

One company who are Certified Service Partners to all major Drive Manufacturers. We can provide One Service Contract to cover all your drives on site, regardless of make, type or power rating and for less than the price of a cup of coffee a day. To find out more go to or email us at