Legacy Drives Explained: Why Old Models Still Power Today’s Factories

A legacy drive is an industrial motor drive that’s no longer manufactured or actively supported by the original equipment manufacturer (OEM), but is still in use across production lines. These can include VFDs, servo drives, and DC drives from brands like Allen-Bradley, Siemens, Mitsubishi, and ABB — often from the late 1990s to mid-2010s.

Legacy doesn’t necessarily mean obsolete. Many of these drives were built to last, with industrial-grade components, durable enclosures, and consistent performance in demanding environments. In fact, some legacy drives have become industry workhorses thanks to their simplicity, reliability, and ease of integration with older systems.

Examples of common legacy drives include:

• Allen-Bradley 1305 – A classic VFD still widely used in HVAC and pump applications
• PowerFlex 40 – A compact and cost-effective AC drive now replaced by newer series, but still running strong
• Siemens Micromaster 420 – A go-to for basic motor control in packaging and material handling
• Mitsubishi FR-A740-00120-NA – A legacy VFD still operating in mid-size industrial systems and used as a retrofit for older Mitsubishi models

These drives may not have Ethernet/IP or predictive diagnostics — but for many factories, they don’t need to. As long as the unit controls the motor reliably, supports existing I/O, and avoids production hiccups, it’s doing its job.

WHY MANUFACTURERS STILL RELY ON LEGACY DRIVES

1. Compatibility with Existing Systems

Legacy drives were designed to work with older PLCs, HMIs, and sensors that still function reliably. Swapping one out for a modern equivalent isn’t always plug-and-play. You might face mismatches in voltage ratings, communication protocols, or control logic.

Upgrading one drive can snowball into upgrading the entire control system — costing time, labor, and capital. Many engineers would rather keep the old system intact if it still performs well, especially in low-change environments.

2. Lower Cost and Capital Preservation

Even if a new drive offers energy efficiency or advanced analytics, the upfront cost can be hard to justify. Modern drives often come with higher price tags, software licensing fees, or new programming requirements.

Legacy drives, especially when sourced from reliable resellers like Industrial Automation Co., offer a budget-friendly way to keep operations running without draining resources on complete retrofits.

3. Avoiding Downtime Risk

Switching to a new drive introduces a new layer of risk. Will the new model integrate cleanly with your systems? Will your technicians need training? Will any errors arise during startup?

Legacy drives are often “known quantities.” Maintenance teams understand their quirks, behaviors, and repair methods. Keeping them in use helps avoid unplanned downtime caused by a failed migration or software bug.

4. Hard-to-Replace Infrastructure

Some legacy drives are part of larger OEM panels or custom-built machinery. Removing them would mean rewiring, recertifying, and potentially redesigning entire systems.

In many industries — especially automotive, aerospace, packaging, and food — such infrastructure changes are a significant disruption. As long as the old drive still meets performance specs, it’s often smarter to leave it in place.

5. Proven Reliability and Track Record

Legacy doesn’t mean fragile — it often means field-tested. Some drives, like the PowerFlex 40 or Allen-Bradley 1305, have been running for 20+ years without major faults. That kind of proven reliability is valuable when uptime is everything.

In the words of one engineer: “If it’s not broken, why replace it with something you don’t know yet?”

WHAT TO DO WHEN A LEGACY DRIVE FAILS

Eventually, every drive has its day. But when that day comes, you don’t always need a full system upgrade. You have options:

• Buy a replacement part from a legacy parts reseller – Industrial Automation Co. stocks hundreds of tested, warrantied legacy drives ready to ship same-day.
• Send your drive in for repair – Our certified repair team can evaluate and rebuild many drives for a fraction of the cost of replacement.
• Ask about a compatible retrofit model – We can recommend modern equivalents that require minimal reprogramming or wiring adjustments.

YOUR PARTNER IN LEGACY DRIVE SUPPORT

At Industrial Automation Co., we understand the reality of keeping production running. We stock a wide range of new and legacy drives, including those from Allen-Bradley, Siemens, ABB, Yaskawa, and Mitsubishi — all backed by our rigorous testing process and a 2-year warranty.

Whether you need an emergency replacement, a long-term support plan, or expert advice on your next move, we’ve got you covered.

🟦 Ready to keep your systems running? Contact us today or browse our inventory to find your legacy solution.