1. Introduction: The Problem with Legacy Motors
Legacy motors-older electric motors that have been in use for 10 years or more-were built for a different time. Back then, energy efficiency and precise control weren't top priorities. Today, these motors waste a lot of energy because they run at a constant speed, even when the task doesn't require full power. For example, a pump or fan powered by a legacy motor might run at 100% speed all day, even when only 50% speed is needed. This wastes electricity and drives up your monthly bills. Legacy motors also require more maintenance because their parts are old and hard to replace. Many older motor models are no longer made, so finding spare parts can be expensive and time-consuming, leading to costly downtime for your business. Additionally, legacy motors often have poor performance, with inconsistent speed and torque that can affect the quality of your work. The solution? Retrofitting these motors with Siemens VFDs. A Siemens VFD can turn an inefficient legacy motor into a modern, energy-saving machine without the high cost of buying a brand-new motor.
2. Why Retrofit Legacy Motors with Siemens VFDs?
Retrofitting with Siemens VFDs isn't just a "nice-to-have" upgrade-it's a practical investment that pays off quickly. Siemens is one of the world's top manufacturers of VFDs, so you can trust their products to be high-quality and reliable.
2.1 Energy Savings with Siemens VFDs
The biggest benefit of retrofitting legacy motors with Siemens VFDs is lower energy costs. Siemens VFDs work by adjusting the frequency and voltage supplied to the motor, so the motor only uses the power it needs to get the job done. For example, if a fan only needs to run at 70% speed, a Siemens VFD will reduce the power to match that speed, cutting energy use by up to 30% (or more) for that motor. Over two-thirds of a plant's auxiliary power demand comes from electrical drive systems, and about 30% of these systems could be run more efficiently with Siemens VFDs. A real-world example: a chemical plant in Turkey retrofitted its old motors with Siemens VFDs and reduced power consumption by 12.1% every year, along with 40 tons of CO2 emissions. These savings add up fast-many businesses recoup the cost of the Siemens VFD within 6 to 12 months.
2.2 Reduced Maintenance Costs
Legacy motors break down often because they run at full speed nonstop, which puts a lot of stress on their parts. Siemens VFDs reduce this stress by controlling the motor's speed and starting it smoothly. This means less wear and tear on bearings, belts, and other components, so you'll spend less money on repairs and replacement parts. Also, many older VFD models (like the Siemens 6SE70) are no longer supported, making spare parts hard to find. Retrofitting with newer Siemens VFDs (like the SINAMICS S120 or G120) ensures you can easily get spare parts and support when you need them. Siemens VFDs also have built-in diagnostic features that alert you to potential problems early, so you can fix issues before they turn into costly breakdowns. This proactive maintenance saves you time and money in the long run.
2.3 Improved Motor Performance and Control
Siemens VFDs give you precise control over your legacy motors. You can adjust the speed, torque, and acceleration of the motor to match the exact needs of your task. For example, a conveyor belt powered by a legacy motor might have uneven speed, leading to product jams. With a Siemens VFD, you can set a consistent speed, reducing jams and improving productivity. Siemens VFDs also offer features like vector control, which improves the motor's performance even at low speeds. This is especially useful for applications like pumps, fans, and compressors, which often need to run at varying speeds. Whether you're running a small pump or a large industrial conveyor, a Siemens VFD will make your legacy motor work better and more reliably.
2.4 Compliance with Modern Standards
Many countries and regions have new energy efficiency standards for industrial equipment. Legacy motors often don't meet these standards, which can lead to fines or penalties. Siemens VFDs help your legacy motors comply with these standards by improving their energy efficiency. For example, the SINAMICS V50 Siemens VFD is designed specifically for retrofitting fixed-speed motors to meet modern energy requirements, with 100% linear voltage output to avoid harmonic issues. Retrofitting with Siemens VFDs also helps your business reduce its carbon footprint, which is good for the environment and can improve your brand's reputation.
3. Key Cost-Effective Strategies for Siemens VFD Retrofitting
Retrofitting legacy motors with Siemens VFDs doesn't have to be expensive. With the right strategies, you can keep costs low while still getting all the benefits of this upgrade.
3.1 Prioritize High-Energy-Use Motors First
Not all legacy motors need to be retrofitted at the same time. To save money upfront, focus on the motors that use the most energy. These are usually large motors (5 HP or more) that run for long hours every day-like pumps, fans, and compressors. Retrofitting these high-energy-use motors with Siemens VFDs will give you the biggest energy savings, so you can recoup your investment faster. For example, if you have 10 legacy motors and 3 of them use 60% of the total energy, start with those 3. You can retrofit the rest later as your budget allows.
3.2 Choose the Right Siemens VFD Model for Your Motor
Siemens makes a wide range of VFD models, so it's important to choose one that's compatible with your legacy motor. Choosing the wrong model can lead to higher costs and poor performance. To keep costs low, select a Siemens VFD that matches the motor's horsepower (HP) and voltage. You don't need to buy a more powerful VFD than your motor requires-this will only waste money. For example, if you have a 10 HP legacy motor, a 10 HP Siemens VFD (like the SINAMICS G120 or V20) is the right choice. Siemens also offers retrofit guides to help you replace older VFD models (like the Micromaster 440) with newer, more efficient ones with minimal wiring changes. Consult a Siemens expert if you're not sure which model to choose-this will save you time and money in the long run.
3.3 Reuse Existing Motor Parts When Possible
One of the biggest cost-saving tips for Siemens VFD retrofitting is to reuse as many existing motor parts as possible. You don't need to replace the entire motor-just add a Siemens VFD to control it. In many cases, you can also reuse the motor's wiring, mounting brackets, and other components. For example, if your legacy motor has good wiring, you can connect the Siemens VFD to it without buying new wires. This reduces the cost of the retrofit significantly. You can also reuse the motor's enclosure if it's still in good condition. Just make sure the enclosure is compatible with the Siemens VFD-if not, you may need to make small modifications instead of buying a new one.
3.4 Hire a Certified Siemens VFD Installer
While it may be tempting to install the Siemens VFD yourself to save money, this can lead to costly mistakes. A certified Siemens VFD installer has the expertise to install the VFD correctly, ensuring it works with your legacy motor and meets safety standards. They can also help you set up the VFD's settings to maximize energy savings and performance. A poorly installed Siemens VFD may not work properly, leading to higher energy bills, motor damage, or even safety hazards. Hiring a certified installer may cost a little more upfront, but it will save you money in the long run by avoiding costly repairs and downtime. Many Siemens partners offer affordable installation services, so be sure to shop around for the best price.
3.5 Take Advantage of Siemens Rebates and Incentives
Siemens and many utility companies offer rebates and incentives for businesses that retrofit legacy motors with energy-efficient Siemens VFDs. These rebates can cover a portion of the cost of the VFD and installation, reducing your upfront expenses. For example, some utility companies offer rebates of up to $500 per Siemens VFD installed. Siemens also offers special pricing for businesses that retrofit multiple motors at once. Be sure to check with your local utility company and Siemens to see what rebates and incentives are available in your area. This is an easy way to save money on your retrofit project.
4. Step-by-Step Guide to Siemens VFD Retrofitting
Retrofitting a legacy motor with a Siemens VFD is a straightforward process, especially if you follow these steps. This guide will help you understand what to expect, from planning to installation and testing. Remember, if you're not comfortable with any step, hire a certified Siemens VFD installer to help:
4.1 Assess Your Legacy Motor
First, you need to assess your legacy motor to make sure it's suitable for retrofitting with a Siemens VFD. Check the motor's HP, voltage, and age. Most legacy motors made after 1970 can be retrofitted with a Siemens VFD, but older motors may need minor repairs first. You should also check the motor's insulation class to ensure it can withstand the temperature changes caused by the VFD. Use an insulation tester to check that the motor's insulation is above 1 MΩ-this ensures it's safe to use with a VFD. If your motor is in poor condition (e.g., broken bearings, faulty wiring), repair it before installing the Siemens VFD. This will ensure the motor works well with the VFD and lasts longer.
4.2 Choose and Purchase the Right Siemens VFD
Once you've assessed your motor, choose the right Siemens VFD model. As we mentioned earlier, select a VFD that matches your motor's HP and voltage. You can buy Siemens VFDs directly from Siemens or from authorized Siemens distributors. Be sure to ask about rebates and incentives when you purchase the VFD. Popular Siemens VFD models for legacy motor retrofitting include the SINAMICS G120 (for general use), SINAMICS V20 (for small to medium motors), and SINAMICS V50 (for fixed-speed motor upgrades). If you're replacing an older Siemens VFD (like the 6SE70), consider the SINAMICS S120, which is designed for easy retrofitting with minimal downtime.
4.3 Prepare for Installation
Before installing the Siemens VFD, turn off the power to the legacy motor and disconnect it from the electrical supply. This is crucial for safety-never work on an electrical motor or VFD without turning off the power first. Gather the tools you'll need, including a screwdriver, wire stripper, multimeter, and insulation tester. You should also read the Siemens VFD installation manual carefully. The manual will give you step-by-step instructions for installing the VFD, including wiring diagrams and safety precautions. If you're reusing existing wiring, check that it's in good condition-replace any frayed or damaged wires.
4.4 Install the Siemens VFD
Install the Siemens VFD in a clean, dry area with good ventilation. The VFD should be mounted away from heat sources (like other motors) and moisture, as this can damage the device. Follow the wiring diagram in the manual to connect the VFD to the motor and electrical supply. Connect the input power to the VFD's R/L1, S/L2, and T/L3 terminals, and the motor to the U, V, and W terminals. Make sure all connections are tight and secure to avoid electrical noise or interference. Ground both the motor and the VFD to ensure safety. If you're not sure how to wire the VFD, hire a certified installer-this is not a step to skip.
4.5 Test and Optimize the Siemens VFD
After installing the Siemens VFD, turn on the power and test it. Start with a low speed and gradually increase it to make sure the motor runs smoothly. Check the VFD's display for any error messages-if you see an error, refer to the manual to fix it. Use the VFD's settings to optimize performance and energy savings. For example, set the acceleration and deceleration times to match your task, and enable the energy-saving mode if available. You can also use Siemens' DriveMonitor software to optimize the VFD's firmware and settings for your specific application. Test the motor for a few hours to ensure it works properly with the Siemens VFD. If everything is working well, you're done!
5. Real Benefits of Siemens VFD Retrofitting
While cost savings are a big reason to retrofit legacy motors with Siemens VFDs, there are many other benefits that can improve your business. These benefits go beyond money and can help your business run more smoothly and efficiently:
5.1 Longer Motor Lifespan
Siemens VFDs reduce stress on legacy motors, which means the motors will last longer. By controlling the motor's speed and starting it smoothly, the VFD prevents wear and tear on components like bearings and belts. This means you won't have to replace the motor as often, saving you money in the long run. For example, a legacy motor that would normally last 10 years can last 15 or more years with a Siemens VFD retrofit. This is a huge benefit for businesses that rely on their motors for daily operations.
5.2 Quieter Operation
Legacy motors are often loud because they run at full speed all the time. Siemens VFDs reduce the motor's speed, making it quieter. This is especially beneficial if your motors are in a workplace where noise levels are a concern (like an office or a small factory). The SINAMICS V50 Siemens VFD, for example, operates at as low as 67dB, making it one of the quietest VFD models available. Quieter motors can improve working conditions for your employees and reduce noise pollution.
5.3 Increased Productivity
Siemens VFDs improve motor performance, which leads to increased productivity. With precise speed control, you can get more done in less time. For example, a fan with a Siemens VFD can run at the exact speed needed to cool a room, reducing energy use while still keeping the room comfortable. A conveyor belt with a Siemens VFD can run at a consistent speed, reducing product jams and increasing output. Siemens VFDs also reduce downtime because they have built-in diagnostics and require less maintenance. This means your motors will be running more often, so you can meet production goals faster.
5.4 Flexibility for Future Needs
Siemens VFDs are flexible and can be adjusted to meet your changing business needs. If you need to change the motor's speed or performance later, you can easily adjust the VFD's settings-no need to replace the motor or the VFD. Siemens VFDs also support modern communication protocols like PROFINET, which allows you to integrate them with other industrial systems (like PLCs) for better control. This flexibility means your retrofit investment will continue to add value as your business grows.
6. Conclusion: Start Your Siemens VFD Retrofitting Journey Today
Retrofitting legacy motors with Siemens VFDs is the most cost-effective way to modernize your equipment, cut energy costs, and improve performance. Siemens VFDs are reliable, easy to install, and backed by a global leader in industrial technology-so you can trust that your investment will pay off. By following the strategies in this blog, you can keep costs low and get the most value from your Siemens VFD retrofit. Whether you're a small business or a large industrial facility, Siemens VFDs can help you save money, reduce maintenance, and increase productivity. Don't wait-start prioritizing your high-energy-use motors, choose the right Siemens VFD model, and hire a certified installer to get started. The energy savings, reduced downtime, and longer motor lifespan will make your retrofit project worth every penny. Remember, retrofitting with Siemens VFDs isn't just an upgrade-it's an investment in the future of your business.
