DC to AC Conversions: can you save energy?

In recent years, there has been a growing awareness of the importance of energy efficiency in the industrial sector. One of the most significant opportunities for energy savings in industrial applications is the replacement of DC motors with AC motor equivalents.

In this blog post we’ll explore the potential benefits of replacing DC with their AC equivalent and provide an illustration of what improved efficiency could look like in real money terms, achieving both real time cost savings and a ROI of less than 2 years.

Do check out our previous deep-dive blog post on DC motors to get a full picture on the benefits of both.

Energy saving and the rise of the AC motor

AC motors have become increasingly efficient and reliable and the technology has advanced to the point where replacing DC motors with AC motors can significantly reduce energy costs and carbon footprint, while also improving reliability and ease of maintenance.

DC motors have been used for decades in industrial applications, but they are not as efficient as modern AC motors. In general, modern AC motors are more efficient than DC motors.

What considerations do you need to look at?

Efficiency

According to a report from the U.S. Department of Energy, AC motors can be up to 15% more efficient than DC motors in some applications.

This may not seem like a significant difference, but in industrial settings where motors are running constantly, the energy savings can quickly add up. See below for our calculation of what that cost-saving could look like.

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Field Current elimination

One advantage of AC motors is that they do not require the high field currents that DC motors do. DC motors use a magnetic field created by a current flowing through a coil, known as the field current, to produce torque. This field current can be very high, sometimes up to 10% of the motor power rating, which increases the energy consumption of the motor.

In contrast, a standard squirrel cage AC induction motor creates a magnetic field that is generated by the interaction between the stator and rotor windings, thus no field current as such.

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Fluctuating Energy Costs

The cost of energy has been at the forefront of all businesses pressure points in the last couple of years and is a key consideration when evaluating the potential savings of replacing DC motors with AC motors.

A cost-benefit analysis is key to ascertaining the short and long-term capital and operating cost impact for the business.

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Environment

Additionally, the environmental impact of energy consumption cannot be overlooked. Carbon footprint reduction has become a top priority for manufacturing businesses.

By reducing energy consumption through the use of more efficient AC motors, companies could help reduce their carbon footprint and contribute to a more sustainable future.

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Maintenance

Efficiency, reliability and ease of maintenance are also important considerations when selecting motors for industrial applications.

DC motors are known for their reliability, but they tend to require more maintenance than AC motors – so there’s a trade-off discussion to be had.

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Noise levels

Moving to certain types of AC motors can also result in a reduction in audible noise, thus improving the working environment for operators.

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Obsolescence

DC motors are becoming obsolete in certain sectors, which can create issues for companies that rely on them. As technology continues to advance, it can be more difficult to find replacement parts and service providers for older DC motors. The question of whether to replace with new DC motors or AC motors is critical here.

Here at iconsys, we’re able to advise on and support DC and AC motors from ALL the main manufacturers – many other companies do not and focus on AC alone.

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Regulatory Compliance

Finally, companies must also consider their legal responsibilities when it comes to energy consumption and carbon footprint. As awareness of environmental issues grows, governments and regulatory bodies are introducing stricter regulations and penalties for companies that do not comply.

By using more efficient AC motors and reducing energy consumption, you can potentially reduce your exposure to legal and financial risks.

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Overall, replacing DC motors with AC motor equivalents can provide energy savings for most applications, reduce carbon footprint, improve reliability, ease of maintenance, and reduce legal liabilities.

While there may be some upfront costs associated with upgrading to AC motors, the long-term benefits can make it a wise investment for many companies. It all comes down to the application type and future direction of the business.

Square framed AC motors are also readily available, which means that can significantly reduce the mechanical installation time and retain the existing DC motor bedplates and couplings.

A worked example

For example, let’s say you have a 100kW DC motor operating at full load, 24/5 operation, running 48 weeks of the year. The cost of a unit of electricity at 30 pence per kWhr the running costs would be:

100 kW x 120 hrs x 48 weeks x £0.30 = £172,800.00

Using a high efficiency AC motor and drive with an estimated 15% reduction in energy requirements the running costs would be:

85kW x 120 hrs x 48 weeks x £0.30 = £146,880.00

Realising an annual saving of £25,920.00.

That’s typically less than a 2-year payback on investment on an AC inverter and motor solution investment.

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The iconsys solution

It is important to note that the choice between DC and AC motors depends on the specific requirements of the application.

We have a wealth of knowledge on single and multi-drive AC & DC drive control systems on most industrial applications.

With our platform partner supply network for both DC and AC motors, we have access to a range of all the latest products and support from all the major manufactures.

We have a great service support team, ServConnect™, that are ready prepared to support clients on legacy plant and recommend upgrades and replacement converters if required.

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AC motors, particularly three-phase induction motors, are generally more commonly used in industrial applications due to their cost-effectiveness, reliability, and widespread availability. However, DC motors do excel in many applications and there is still a vast number of DC machines currently in operation worldwide which if retained and the drive controller replaced can provide many years of service.

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With our decades of system integration and automation solutions expertise, coupled with our platform independence, means you will always get the right drive choice for your next automation project. It’s not just about finding a DC or AC solution; it’s about finding the RIGHT solution for your needs.

Have a DC application? Or a need to upgrade your current legacy DC drive system system to AC, to prepare for Industry 4? Then please contact iconsys and myself or one of our engineers will contact you.

 

Author: Ian Pickersgill, Heavy Industries Business Development Manager, iconsys