The true cost of motors

Real savings start with knowing the numbers...

Electric motors are the driving force behind many industrial processes, from pumps and fans to conveyors and mixers. However, while they run in the background, their energy consumption can make up a significant share of operational costs. Understanding exactly what a motor costs to run, and how to reduce that cost, requires more than just looking at the energy bill. Here, David Strain, technical director at systems integrator Technidrive, explains how to calculate motor running costs and highlights ways that businesses can use this information to improve energy efficiency and reduce consumption.

Electric motors account for a significant share of industrial power consumption, making them a major contributor to both operating costs and environmental impact. While buying a motor is a one-time expense, it represents less than two per cent of the total cost of ownership (TCO), meaning that the other 98 per cent consists almost entirely of energy usage.

What running costs can tell you
Understanding a motor’s consumption offers financial and operational advantages. Regular monitoring is essential — without it, reducing energy use is nearly impossible. Tracking consumption not only shows where costs come from but also creates a baseline to spot changes.

The data can also highlight issues that might otherwise be undetected. For example, if a motor consumes 50 kW one week and 75 kW the next, that variation may reflect a problem on the line, a motor that is over or undersized, or differences between processes. Recording trends in motor running costs can provide insights to improve overall efficiency and positively impact the bottom line.

Calculating the cost
Motor running costs are primarily dictated by electricity prices, the power rating of the motor and its annual running hours. It is also important to remember that a motor’s rated power indicates its mechanical output, not the electricity it consumes. A less efficient motor will absorb more input power to deliver the same output, while a high-efficiency motor achieves the same output using less energy.

Information needed to calculate running costs can be found on the motor nameplate or via modern energy meters. First, calculate energy usage in kWh by multiplying annual operating time by rated power. Losses can then be factored in using the efficiency rating to estimate total chargeable kWh. Multiplying this by the electricity tariff gives the annual running cost. For example, a 45 kW motor running continuously at €0.28/kWh could cost over €40,000 per year.

Cost cutting strategies
Once businesses understand how their motors are performing, there are several ways to reduce energy use and operating costs. Consulting with an expert to evaluate the system is a useful first step. One of the most effective strategies is smarter control. By fitting variable speed drives (VSDs), motors can run at the speed the application requires, and even small reductions in speed can deliver significant energy savings.

Correct sizing and careful selection also play a crucial role. A motor that meets the actual demands of the application will operate closer to full load, improving efficiency. Beyond the motor itself, evaluating other equipment is important. For example, switching from low-efficiency gear units to more efficient alternatives can significantly reduce energy losses.

Maintenance also matters. Worn or poorly functioning components can force motors to work harder, increasing energy consumption. Simple actions, such as switching equipment off when not needed, can also deliver savings without major investment. Together, these strategies show that savings often come from a combination of smarter choices across motors, drives and the wider plant.

The bigger picture
Calculating motor running costs is an important step for any operation looking to manage energy use, reduce expenses and meet sustainability goals. It allows companies to make informed decisions and identify where improvements can be made.

However, some of the biggest opportunities lie beyond the motor itself. Poor system design, inefficient equipment or insufficient control can all drive up costs. By combining accurate cost calculations with a broader view of systems and processes, businesses can achieve meaningful reductions in both costs and energy consumption.

For further information about on Technidrive’s efficient motor and drive solutions visit the website.