iMEC – Intelligent Motor Energy Controllers
AC induction motors are the most common piece of electro-mechanical engineering on the planet and account for over half of all electrical consumption world-wide.
Motors are widely used in both commercial and industrial manufacturing processes. Unsurprisingly, almost every product we buy is made with the aid of a motor and therefore the cost of running motors has a direct impact on the cost we pay for all the products we purchase.
Motors can be incredibly wasteful due to the inefficient and rather basic design of the motor, which has changed very little in well over a century. The conversion of electrical energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. Around the time of the industrial revolution it seemed to matter little what they cost to run… now we know better and as it turns out electric motors are not just the world’s biggest user… they are also the world’s biggest abuser of energy.
The purpose of an AC Induction motor is quite simple. The National Grid provides a convenient source of power, in this case electrical energy, and the job of the motor is to convert that power into a usable form namely; mechanical energy (torque). This can then be utilised in a facility remote from the source of power generation to turn, pull, push or drive something as part of an industrial or commercial process. The efficiency of the motor can be summed up in its ability to convert as much of the electrical energy it consumes into a job of ‘work’. In terms of inefficiency (wasted energy), almost all losses can be evidenced in the form of unwanted heat, noise and vibration.
When a motor manufacturer calculates, and subsequently publishes their figures on the efficiency of their range of motors, those calculations are often based on ideal conditions that are rarely encountered in the field.
Motors can waste significant amounts of energy for any combination of the following reasons:
- When mated to an appliance, motors are all too often over-sized to the next available model – for obvious reasons they can never be downsized. Sometimes an appliance manufacturer will use a standard motor for much of their range of products in order to obtain the best possible price point and for ease of storage and on-site servicing/replacement. We have seen cases where motors have been 100% over-sized.
- Almost everywhere there is evidence of fluctuations in power supply on the National Grid. The fact remains that despite assurances to the contrary from utility companies the motor designers know these figures can vary considerably and they have to design their motors to work under the worst-case scenario i.e. when the voltage is below the nominal figures. In reality, if a motor was not able to cope with a reduction in available power even for a relatively short period when fully loaded it could easily burn out – worst still catch fire!
- The duty cycle on the motor will often vary dramatically, with variations ranging from 100% loading down to 0% loading. While there is a measure of reactance within the motor windings it is widely accepted that the humble AC Induction motor has no way of intelligently adjusting the amount of power it consumes in relation to the job of work it does. An escalator for example has to be able to carry two adults on each step in an upward direction. Often there is only one person to move which means substantially less energy is needed – add to that the fact that half of the world’s escalators are going downhill and you begin to understand the potential for waste as motors cannot adjust consumption for these extremes.
- When starting direct on-line, an AC Induction motor can draw massive inrush currents, typically between 6-9 times normal full load current. This can have a very negative impact on maximum demand charges. Furthermore, this problem can translate to 300% increases in shock load transferred to the mechanical transmission systems often leading to premature mechanical failure. At the other end of the duty cycle a lightly loaded motor will become a much more ‘inductive’ as opposed to ‘reactive’ load. This is often the major cause of poor power factor at site level, and along with increased peak demand can massively increase punitive charges – in some cases doubling the kilowatt units charged for the billing period. Poor power factor can also have the effect of shrinking the amount of available power on a site.
Losses in the system create a number of further mechanical problems… when a motor draws more power than it is able to convert to mechanical energy (work), then the excess has to be immediately and irreversibly converted by the motor to another source of energy namely; heat, noise and vibration. This has a further negative effect on the performance and life of the equipment leading to increased maintenance costs and reduced life expectancy.
Following extensive research and development, BEST have made considerable advances in the field of intelligent motor control technology. The dynamic software utilized in the iMEC single-phase motor controller is an integral part of both the patent protected ACES and CUES Hybrid solutions.
As a motor goes through its duty cycle (in response to demand changes at the motor shaft), there will be a proportional effect on the ‘values’ of the power that is being drawn. iMEC uses this feedback from the motor as it comes along the power cable to allow the motor to act as its own load sensor.
iMEC will constantly monitor the ‘load’ on the motor every 100th of a second and ensure the motor has only the exact amount of power it requires at any instant in time to do the required job of work. iMEC will also enable the motor to run as a much more ‘resistive’ load thereby further improving power factor quality.
Initial starting of the motor is made much smoother thanks to the introduction of controlled acceleration. Power is ramped up gradually at each starting cycle, which minimizes wear and tear in addition to reducing maximum demand charges often associated with starting loaded motors.
In effect iMEC electronically ‘sizes’ the motor to both its application and load cycle every fraction of a second, ensuring the motor uses just the right amount of power it needs to at any instant in time – no more – no less!
The iMEC range of Intelligent Motor Controllers will:-
- Save up to 40% in energy costs
- Reduce peak demand charges
- Improve power factor
- Reduce heat, noise and vibration
- Reduce maintenance costs
- Extend equipment life
BEST manufacture a range of iMEC solutions for single-phase applications up to 20AMP. A full range of proprietary 3-Phase applications is also on hand with special orders available ranging from 3-1000 kW.