AC induction motors have changed the commercial and industrial landscape by simplifying processes and reducing the amount of manual labor required to carry out certain manufacturing functions. However, AC induction motors, being some of the most commonly-used electro-mechanical engineering pieces, account for more than half of global electrical consumption.
AC induction motors have become an irreplaceable part of both industrial and commercial establishments. Every electrical product we buy has a motor. As such, it’s not surprising to know that the cost of running motors has a direct effect on the price we pay while purchasing the products.
How do AC induction motors work?
An AC induction motor has a very simple purpose. The National Grid supplies power from a source, and the motor’s job is to convert the electrical power into a usable form of mechanical energy. This mechanical energy, measured in torque, is used in facilities to push, pull, turn or drive something as a part of a commercial or industrial process.
The efficiency of an AC induction motor is seen in its ability to convert the consumed electrical energy into “work done”. But losses in the form of noise, heat, and vibration show that motors waste energy and prove to be inefficient at times. However, it is important to note the calculation of efficiency. A motor manufacturer bases their efficiency calculation on ideal conditions, which are rare to achieve in the field.
What’s the problem with AC induction motors?
Motors have no doubt simplified a number of processes in commercial as well as industrial setups, but have posed threats to energy resources at the same time. An AC induction motor proves highly wasteful due to its basic, rather inefficient design, which has remained consistent for over a century now.
British Scientist, Michael Faraday, demonstrated the conversion of electrical energy into mechanical energy in 1821. Since the cost was never an issue, AC induction motors were widely used during the industrial revolution. But now, these motors have become one of the largest abusers of energy in the world, posing grave threats to electrical energy resources.
There is a significant loss of energy with AC induction motors because of the following reasons:
- Inappropriate size
When motors are connected to an electrical appliance, they often tend to be oversized. Since their size cannot be decreased, these motors prove to be unsuitable for the next available model. Moreover, appliance manufacturers use standard motors in their products so that they can offer the best price and ensure ease in storage, servicing and replacement. In some cases, the motor was 100 percent oversized, thus contributing immensely towards energy wastage.
- Fluctuations in power supply
Fluctuations in power supply from the National Grid is a common phenomenon. Despite assurances from utility companies, the supply of power continues to remain the same. The high energy consumption rate can be attributed to the poor design of motors, hiking the voltage above nominal figures. In a worst-case scenario, the motor would burn out or catch fire if it is unable to cope with power reduction even for a short period of time.
- Varying duty cycle
The duty cycle in AC induction motors varies in the range from zero percent loading to 100 percent loading down. A standard AC induction motor has no way to make adjustments in the amount of power it consumes in relation to the work done. Since AC induction motors have no mechanisms to reduce power consumption, the resulting energy wastage is quite high.
- Huge inrush currents
On connecting an AC induction motor directly to an energy source, it draws massive amounts of inrush currents. The rate at which the motor draws current is at least six to nine times the normal full-load current. Such a high rate of current usage has a negative effect on maximum demand charges. Moreover, an AC induction motor can translate to 300 percent more shock load transmitted to the mechanical systems and cause a premature failure.
In hindsight, a motor which is loaded lightly will prove much more “inductive” than “reactive”. More often than not, this is attributed to poor power at the site. But increased demand also influences the punitive charges, often increasing them and charging almost double for kilowatt charges during the billing period. Moreover, the amount of power available on the site can also reduce after the power supply is disturbed.
Losses in an AC induction motor also give rise to a number of mechanical problems. When the motor draws more current than it can actually convert to work, the excess current is irreversibly and immediately converted to another source of energy such as noise, heat, and vibrations. Such losses in energy have a negative impact on the overall performance of electronic appliances. Moreover, such issues decrease the life of the appliance and increase its maintenance costs.
What’s the solution for such power losses?
Considering the alarming contribution of AC induction motors towards power wastage, companies around the world have tried to come up with solutions to curb power wastage.
iMEC uses a dynamic software, which is an essential part of the patented CUES and ACES Hybrid solutions. As iMEC traverses through its duty cycle, a significant change is expected in the power drawn by it. The change in the value of power consumed by the motor will change in response to changes in demand at the motor shaft. iMEC single-phase motor controller uses this feedback as it travels along the power cables to activate the motor’s own load sensing abilities so that it does not consume more power than it can convert to work.
iMEC has the ability to monitor the power load on the motor every 100th of a second and ensures that the motor consumes only the exact amount of power that it requires to get the work done. iMEC is expected to improve the quality of power factor by enabling the motor to run as a restrictive load. The controlled acceleration makes starting the motor a lot smoother. Power is increased gradually at each stage, which reduces depreciation and minimizes demand charges, which increase with starting loading motors.