How could industrial enterprises reduce their power consumption without making any revolutionary transformations?

Today, when the optimization of power consumption is extremely relevant, a business could benefit from knowing about all the possibilities for the smart use of power resources. One of the possible ways is to transform or renew electric motors used in the company. This method is particularly attractive because it does not require any fundamental changes in the company’s processes.

Electric motors are widely used in industry – wherever devices lift, rotate, transport or otherwise move something. Ventilation equipment installed in buildings (fans, air conditioners), water and heat system equipment (pumps), and, for example, lifts, also have motors.

“The motor transforms electrical power into mechanical – movement. The more economical the motor, the less electricity it consumes to produce that movement. And lower power consumption means more efficient production and lower production costs. Therefore, the modernization of electric motors or the efficiency of their management is a power saving potential for companies,” says Eimantas Daunoras, head of the Drives and Automation Department at PakMarkas UAB.

Upgrade the motor or use a frequency converter?

Motors are one of the components of the system, so there are even several ways to optimize the device’s power consumption. The most effective, of course, is to modernize the entire system – reducing costs by 60% is possible this way. However, significant savings can also be achieved by replacing only the motor, and an even greater effect will be felt by installing (or updating) a frequency converter that optimizes motor control. It is not difficult to do that.

PakMarkas, a packaging, robotics and engineering solutions company, calculates that replacing a standard (IE1) motor with a motor of super premium efficiency (IE4 class) would pay off within one year. If you choose a 7.5 kw device, the investment will amount to approximately EUR 1000. Over ten years, this renovation would save an average of EUR 9,320 (6.3%)

Frequency converters would enable saving much more – up to 30%. Frequency converters increase the efficiency of electric motors, as they allow you to adjust the motor power depending on the load, use the braking energy, which in the absence of the converter evaporates in the form of heat. Frequency converters also enable soft starting and stopping of the motor (not only power consumption decreases, but also the operating time of both the motor and the entire system increases), remote control, it is possible to monitor how long the motor works and how much electricity it consumes.

„Sensors that measure process parameters can be connected to the frequency converter, and the motor can be controlled accordingly. If the motor is connected to the network without a converter it will work in the same mode all the time. For example, a 100 kW pump in a water supply system that pumps water into the system will operate at maximum capacity without a converter. And by using a frequency converter with a sensor that measures water consumption and pressure in the system, the pump will work at full capacity only at peak times, when everyone needs water. As the consumption drops, the motor power will start decreasing, and at night it may even turn off,” explains E. Daunoras.

Example: replacing a pump with an old motor of standard efficiency IE1 and a soft starter with a new 7.5 kW motor operating with a frequency converter G120 would cost 2150 EUR. The investment would pay off in four months, and in the long (ten years) period, it would allow saving EUR 68,170 or 49 percent power costs.

It is true that the calculations were made on the assumption that the motors are running at full load around the clock, and in practice no equipment operates this way. Therefore, the actual savings are likely to be somewhat lower – in the case of pump modernization, saving 25-35 percent is feasible.

Where to start

According to Arūnas Olšauskas, the representative of the motor-producing company Siemens in Lithuania, the easiest way for industrial companies with many electric motors to reduce power consumption is to replace old motors with new ones of IE4 efficiency class. If there are places in the company where motors work continuously at full capacity, he recommends optimizing motor speed control using frequency converters in those places.

„Of course, each case is individual, however, when it comes to renewing motors, I would definitely recommend changing those IE1 class motors, which have already been repaired (rewound), or those that do not have any efficiency marking on the motor plates,” advises A. Olšauskas.

From July 2023, the motor directive will enter into force in the European Union obliging motor manufacturing companies to supply high-efficiency class motors, and manufacturers installing motors in their own equipment will also be required to use more efficient motors.

PakMarkas has a very wide range of different motors (three-phase asynchronous, low-centre, drum, etc.) and frequency converters supplied by world-renowned manufacturers. Motors of various specifications are available, depending on the nature of the motor operation and the customer’s field of activity, and for the convenience of customers, the company always has reducers of different sizes and transmission ratios in stock, which can be quickly installed on the selected motor.

„Some companies buy a more efficient motor only when the old one breaks down. But there are also those that change all their motors at once. You need to calculate, because if the motor is of a lower efficiency class, but is not yet old and does not work much, it is unlikely that changing it will pay off – or it will take very long. However, for companies that „employ” many motors and especially if they are older generations and operate intensively, this is a really fast and relatively simple way to reduce power consumption,” says PakMarkas’ expert E. Daunoras.