A failed drive can stop a production line long before a replacement reaches site through the standard channel. For maintenance teams supporting ageing machinery, a guide to refurbished drive procurement needs to focus on one thing: obtaining the correct, usable unit without creating a second fault or extending downtime. Price matters, but part-number accuracy, condition evidence and delivery certainty matter more.
Refurbished variable speed drives, servo drives and legacy motion products can be a practical route when OEM stock is unavailable, lead times are long or a discontinued series remains installed across the plant. The purchase only works, however, when procurement, engineering and maintenance agree on what constitutes a compatible replacement. A drive that looks similar, shares a power rating or comes from the same manufacturer is not necessarily a safe substitute.
Start With the Complete Identification Code
The full manufacturer part number is the purchasing baseline. Capture it directly from the failed unit, the electrical drawings and, where available, the machine bill of materials. Record every suffix, series identifier, voltage designation, firmware reference and option code. A single character can distinguish a different mains supply, communications interface, feedback type, enclosure rating or safety function.
For a Siemens, Allen-Bradley, Mitsubishi, Schneider or Omron drive, the product family alone is not enough. A buyer requesting a "5.5 kW inverter" may receive several technically plausible options, yet only one may match the existing control architecture and motor arrangement. Use the original part number in the enquiry and ask the supplier to confirm the offered number in writing.
It is also worth identifying whether the unit is an exact replacement, a functional equivalent or a proposed upgrade. These are different procurement decisions. An exact replacement is normally the lowest-risk option during an urgent breakdown. An equivalent or upgrade can be sensible where the original is obsolete, but it may require parameter conversion, wiring changes, software work and planned commissioning time.
Check the Application, Not Just the Rating Plate
Before ordering, confirm the application details with the engineer responsible for the equipment. Motor voltage and current, control method, braking arrangement, encoder or resolver feedback, fieldbus protocol and environmental conditions should all be checked. If the drive controls a hoist, winder, safety-critical axis or high-inertia load, include that information at the enquiry stage.
A replacement can have the correct nominal output yet be unsuitable because it lacks an encoder card, brake transistor, STO configuration or the required network module. Similarly, a drive supplied for 400 V operation cannot be assumed suitable for a 480 V installation merely because the motor size appears comparable. The rating plate, manuals and original drawings should guide the decision.
A Practical Guide to Refurbished Drive Procurement
Refurbished does not mean one universal condition. In the secondary market, the term can cover anything from a cleaned and function-tested unit to a component-level repaired drive with replaced wear items and documented load testing. Procurement should ask what work has actually been completed rather than relying on the label alone.
A useful supplier response should state the condition clearly and separate refurbished stock from new and sealed inventory. It should also identify whether accessories shown in catalogue images are included. Keypads, covers, option cards, terminal blocks, mounting hardware and parameter memory modules are frequently required for a like-for-like swap, but are not always supplied with the main unit.
Ask these questions before raising the order:
- Is the offered item the exact manufacturer part number, including suffix and revision where relevant?
- What testing has been completed, and was the unit run under load or only powered up?
- Were faulty components replaced, and has the unit been inspected for damage, corrosion or poor previous repair work?
- What warranty period and return process apply if the drive fails on installation?
- Is the item physically in stock, and when can it be dispatched?
Testing Evidence Should Match the Risk
For a low-cost spare intended for bench evaluation, a simple functional test may be proportionate. For a drive going straight into a critical production asset, request more detail. Good evidence can include confirmation of power-up checks, I/O checks, communications testing, output testing, fault-history review where supported, and load or motor testing. The exact procedure depends on the product and available test equipment, so avoid assuming every test is possible for every legacy model.
There is a trade-off here. A specialist supplier may charge more for properly assessed stock than an untested surplus seller. That difference can be justified if it avoids a repeat shutdown, emergency labour costs and another freight charge. Conversely, where the plant has in-house repair capability and the unit is non-critical, a lower-cost as-is purchase may be acceptable if it is specified and priced accordingly.
Manage Compatibility and Configuration Risk
Drives often hold application-specific parameters that do not transfer automatically. Replacing hardware is only part of the task. Before the failed unit is removed, save the parameter set where possible and photograph wiring, option cards and display settings. Keep a copy of the programme, firmware information and commissioning notes with the asset record.
If the original drive has already failed and its parameters cannot be recovered, use the machine documentation and a known-good unit from an identical asset as references. Do not copy parameters blindly between drives with different motor ratings or revisions. Verify motor data, acceleration and deceleration limits, current limits, control source, analogue scaling and safety settings during commissioning.
Firmware deserves particular attention on networked or servo applications. An otherwise matching unit may communicate differently with an existing PLC, HMI or motion controller if firmware revisions are materially different. Ask the supplier what revision is fitted if it is visible or testable, but treat that answer as part of the engineering assessment rather than a guarantee of drop-in operation.
Buy for the Immediate Repair and the Next Failure
When an installed base includes legacy drives, purchasing one replacement at a time keeps each breakdown exposed to market availability. A more effective approach is to identify critical drive families and hold suitable spares for the assets that cannot tolerate delay. This does not mean buying every obsolete part available. It means ranking equipment by production impact, replacement difficulty and availability.
For high-risk assets, consider holding an exact configured spare, relevant option modules and a backed-up parameter file together. Label the set with the machine reference and storage date. Periodic inspection matters because stored electronics can be misplaced, damaged or stripped for parts over time.
Secondary-market procurement is particularly useful where an OEM has moved a product to end-of-life status or cannot meet an urgent requirement. Independent multi-brand stock can also help buyers source related PLC, HMI and control components at the same time. That said, a refurbished replacement should not prevent a longer-term modernisation decision where repeated failures, unsupported software or unavailable spares are becoming a pattern.
Separate Emergency Buying From Planned Replacement
Emergency orders favour speed and exact match. Planned projects allow time to assess lifecycle status, alternatives, panel changes and commissioning requirements. Combining the two processes often creates poor outcomes: either the emergency repair is delayed by unnecessary redesign, or a strategic upgrade is rushed into service without adequate testing.
Set a simple internal rule. For a production-stopping failure, source the closest verified replacement first and restore the machine. Then open a follow-up review covering root cause, spare strategy and whether the drive family should be upgraded during planned downtime. This gives maintenance the parts it needs while allowing engineering to make a controlled decision.
Assess the Supplier as Carefully as the Part
A practical supplier should be able to discuss the offered part number, condition and stock position plainly. Be cautious of vague descriptions such as "compatible", "replacement" or "tested" when no supporting detail is available. Clear photographs can help verify labels and cosmetic condition, although photographs should not replace a written confirmation of the exact item supplied.
Confirm dispatch location, carrier cut-off times, packaging method and whether export paperwork is needed. Drives are sensitive electronic products and should be packed to prevent impact, moisture and electrostatic damage. For a shutdown situation, ask whether the stock is ready to ship rather than assuming a catalogue listing reflects immediate availability.
Also review the warranty and returns process before purchase. A fair policy will not eliminate installation risk, especially with old equipment and unknown field conditions, but it establishes what happens if the supplied unit is incorrect or demonstrably faulty. Keep the original packaging until the replacement is fully commissioned.
Automation Planet UK can assist with part-number-specific enquiries across major automation brands, including refurbished and new and sealed stock where available. Providing the full code, photos of the rating plate and the urgency of the requirement helps speed up the quotation process.
The best refurbished drive order is usually the least dramatic one: the correct code is verified, its condition is understood, the configuration is ready, and the machine returns to service without an avoidable second delay.