Effective Maintenance: Energy efficient motors and drives enable cost and carbon savings

Motors and drives form the backbone of industrial processes. Es­timates suggest that these acco­unt for nearly 70 per cent of the industrial electricity consumption and around 40 per cent of the commercial consumption. Therefore, it is essential to optimise energy use and adopt measures to en­han­ce energy efficiency in motors and drives. Energy efficient motors (EEMs) have a potential to significantly lower en­ergy costs and environmental effects. Since electric motor systems account for a sizeable portion of all electricity consumption, using EEM systems in both new installations and accelerating the replacement of old inefficient motors could result in significant cost savings.

While upgrading a motor can result in significant efficiency benefits, using a hi­gh-efficiency motor in conjunction wi­t­h a variable-speed drive (VSD) can re­sult in even more energy savings.

The majority of motors in India use a lot of energy and are inefficient, which causes problems such as high operating costs and significant emissions from industries and power plants. Around 90 per cent of the motors that are now ins­tall­ed are estimated to be at the IE1 and sub-IE1 levels. Additionally, because the majority of these motors have been operating for 15 years or longer, they frequently fail and need maintenance. The operations and maintenance (O&M) costs of industrial units are substantially increased by the use of inefficient motors.

National Motor Replacement Programme

EESL is accelerating the adoption of IE3 motors for motor replacement under the National Motor Replacement Prog­ram­me (NMRP). The customer is not required to make any upfront payments under the programme. By monetised energy savings, EESL is repaid. The programme aims to replace the currently installed lower efficiency motors, which are old and have been rewound multiple times over their lifetime, with new IE3 mo­tors. Under this programme, EESL is offering IE3 motors ranging from 1HP to 100 HP to Indian industries. This programme is advantageous for MSME as well as non-MSME industries.

According to an estimate by EESL, more than 2 million motors produced in the country have the potential to save more than 5 billion kWh annually, or $500 million per annum, which might result in avoidance of 600 MW of generation ca­pacity. In the initial phase, EESL plans to replace 120,000 motors. The NMRP in India conducted 36 motor pilot studies in the cities of Ahmedabad, Surat, Jam­nagar and Mumbai in 2018. It found power savings across all pilot installations by swapping out standard efficiency motors with premium efficiency IE3 motors in compressors, pumps, fans and blowers used in the brass, textile, chemical and automotive industries. The NMRP began exploring the possible effects of upgrading 5,000 standard efficiency motors at major corporations and small and medium enterprises na­tionwide. It came to the conclusion that the action would result in 9,150 MWh of ye­arly energy savings, $902,112 in annual cost savings and 8,050 ton­nes of an­nual carbon dioxide emission reduction. During 2021–22, EESL de­ployed 1,920 IE3 motors. As on March 31, 2022, 5,280 IE3 motors have been deployed in the industry.

Energy efficient motors

EEMs are motor designs that include design advancements intended to maximise operational efficiency over conventional/standard motor designs. Re­du­­cing intrinsic motor losses is the primary objective of design advanceme­nts. The use of lower-loss silicon steel, a longer core (to increase active material), thicker wires (to reduce resistance), thinner laminations, a smaller air gap bet­we­en the stator and the rotor, copper bars instead of aluminium in the rotor, better bearings, a smaller fan and other advan­cements. The country’s EEMs operate with efficiencies that are typically 3-4 per cent greater than those of conventional motors. Accor­ding to the requirements of the Bureau of Indian Standards, EEMs are developed to function efficiently with loads ranging from 75-100 per cent of their rated capacity.

This has significant advantages in a variety of load applications. Moreover, EEMs are often more capable of accelerating higher-inertia loads and are less impacted by supply voltage variations. They also operate at lower operating temperatures and noise levels.

Variable speed drives

Without the intervention of a variable speed drive, an electric motor lacks the ability to regulate activity and is only ca­pable of operating at its maximum capa­city. Alternatively, by including a VSD into the system, the drive can cut or low­er the motor’s output and save energy when a pre-set condition, such as temperature, is met.

Installing VSDs in motors is thus another energy-efficient technique to increa­se motor efficiency. In accordance with the requirements of the application, VSDs alter the speed of an electric mo­tor. Without this adjustment, the system brakes when less power is needed, wasting energy and releasing it as heat. VSDs thus conserve energy with each spin. Industry estimates suggest that slowing a fan or pump motor from 100 per cent to 80 per cent with a VSD can save energy consumption by as much as 50 per cent. In a fan application, for example, VSDs regulate the airflow in accordance with requirements rather than abruptly stopping it when operating at full ca­pacity. Pumps, fans, and compressors are industrial motors where VSDs are most frequently installed because of their frequent and intermittent use due to time, temperature and output requ­ire­ments.

Other emerging trends

  • Digitalisation of operations: Existing motors can be equipped with wirele­ssly connected sensors, allowing for re­mote and transparent performance monitoring. The collected data can be used to optimise processes and realise considerable efficiency gains and en­er­gy savings in a complicated ind­us­trial installation or HVAC system of a large structure. When the monitored motors are remotely or automatically controlled, their performance, system efficiency, and energy savings are further enhanced, making them smart motors. The data produced by sensors can be analysed along with other control data and used by a central control system as the foundation for real-time modifications to the en­tire installation.
  • IE5 grade motors: In recent years, companies have launched the IE5 grade of motors, which incorporate sy­nchronous reluctance technology, to improve efficiency and operational performance. The rotor in a synchronous reluctance motor has no magnets or windings and suffers virtually no power losses. And because there are no magnetic forces in the rotor, ma­­intenance is as straightforward as with induction motors. These motors combine the performance of permanent magnet motors with low O&M cost of induction magnets, to maxi­mise efficiency and minimise downtime. Additionally, the absence of ma­gnetic force in the motor helps reduce temperature in the motor, thereby prolonging the lifetime of the motor and improving its reliability.
  • Soft starters: Soft starters can be used in plants and industrial units to increase the efficiency of motors that are only sometimes or partially in use. The load, torque and start-up electric current surge of the motor are all temporarily reduced by these devices. A slow starter for machinery saves energy and reduces me­chanical stress on the motor and shaft. A soft starter can result in cost savings over the motor’s lifespan, including redu­ced energy expenses and lower maintenance costs.
  • Closed-loop control systems: By comparing the desired output condition with the actual output condition, clos­ed-loop systems are intended to automatically achieve and ma-in­tain the condition. The error signal, which is the difference bet­we­en the output and the reference in­put, is produced in or­der to achieve this. A closed-loop co­ntrol system’s key be­ne­fit is its ca­pacity to lessen a syste­m’s sensitivity to outside disturban­ces and en­han­­ce an unstable syste­m’s stability, am­ong others.


For the system to operate better overall in the future, motor and drive systems mu­st be properly maintained. Effective maintenance programmes can help co­m­panies avoid costly production in­terruptions by reducing the risk of un­planned downtime. Moreover, considerations including operating time, ambient conditions, and failure consequ­en­ces should be taken into account when ins­pecting motor and drive system components. To get pollutants out of the en­gine, these examinations should be done al­ongside cleaning.

Overall, EEMs and VSDs are intended to be adaptable and dependable. They offer significant power consumption sa­vings over earlier systems due to their outstanding efficiency. Electric motors in buildings and industrial ap­plications account for a sizeable portion of the co­untry’s electricity co­n­su­m­ption, the­re­fore, any investme­nt made to upgrade the equipment will pay off in the long run, in terms of efficiency and sustainability.