Variable Frequency Drive (VFD) Repair Services

A variable frequency drive controls the speed and torque of an AC induction motor by converting fixed-frequency input power to a variable-frequency, variable-voltage output. VFDs are among the most common and most failure-sensitive components in industrial motor systems — and when one fails, the motor it controls stops with it.

Renown Electric provides variable frequency drive repair for industrial, municipal, and commercial operations across Canada and the United States. We service drives in our shop facility and in the field, with component-level diagnostics, full load testing, and warranty coverage on all parts and labor.

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Common Causes of VFD Failure

Most VFD failures trace back to a handful of recurring root causes. Knowing what to look for helps maintenance teams catch problems before they become unplanned shutdowns.

Power quality issues are the most frequent cause of VFD damage. Voltage spikes, transients, and unstable supply conditions stress sensitive electronics — IGBT modules, gate driver circuits, and DC bus capacitors — with each event. Facilities without proper line reactors or surge protection accumulate this damage over time until a component fails outright.

Thermal stress accelerates component aging whenever cooling systems can’t keep pace with heat load. Blocked vents, failed cooling fans, and high ambient temperatures all shorten the life of power electronics. In many cases, thermal damage is visible as discoloration on PCBs or deformed capacitors — but by that point, secondary damage has often already spread.

Electrolytic capacitor degradation is a natural aging process that typically surfaces after five to seven years of continuous service. As capacitors lose capacitance and develop increased equivalent series resistance, the DC bus becomes unstable and fault codes become more frequent.

Environmental contamination — dust, moisture, and conductive particles — is a significant threat in mining, pulp and paper, plastics processing, and similar environments. Contamination that reaches PCB surfaces creates tracking paths and short circuits that a drive enclosure is not designed to handle without additional filtration or sealing.

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Our VFD Repair Process

Every VFD that enters our shop follows the same structured workflow, regardless of manufacturer or horsepower rating.

Intake and Documentation — We photograph and log the drive into our tracking system, recording model number, serial number, and reported fault history before any work begins.

Full Diagnostics — Fault codes are extracted and analyzed alongside oscilloscope and multimeter testing of the rectifier section, DC bus, IGBT inverter modules, and gate driver circuits. PCB inspection under magnification identifies cracked solder joints, burned traces, and failed surface-mount components. We identify every degraded component, not just the one that triggered the initial fault.

Component Repair and Replacement — Failed IGBTs, capacitors, gate driver boards, cooling fans, and power supply modules are replaced with OEM or OEM-equivalent parts. High-wear components nearing end of life are flagged and replaced proactively to prevent a repeat failure after the drive returns to service.

Full Load Testing — The repaired drive is tested under load using calibrated equipment to verify torque output, frequency response, and motor control performance under rated operating conditions. This confirms the drive can handle production demands, not just pass a bench power-up.

Documentation and Return — A complete repair report accompanies every unit, documenting parts replaced, test results, and measured parameters. All repairs carry warranty coverage on parts and labor.

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VFD Brands We Service

Our technicians carry brand-specific technical documentation, test fixtures, and parts inventory for all major manufacturers. Commonly serviced brands include:

• Allen-Bradley (Rockwell Automation) — PowerFlex 4, 40, 70, 400, 525, 700, 753, 755
• ABB — ACS355, ACS480, ACS550, ACS580, ACS800, ACS880
• Control Techniques – Unidrive, Vector Flux, Mentor etc.
• Yaskawa — A1000, V1000, GA500, GA700, U1000, and legacy GPD series
• Magnetek – DSD312, DSD412, HPV600, HPV900, M1000, Quattro and GPD series
• KEB – F5, F6, R6
• Siemens — SINAMICS G and S series, MicroMaster, legacy 6SE series
• Schneider Electric — Altivar 320, 600, 630, 680, 900
• Danfoss — VLT and VACON series
• WEG — CFW300, CFW500, CFW700, CFW900, CFW11
• Mitsubishi — FR-A800, FR-E800, FR-D700

If your brand is not listed, contact us. We repair virtually every VFD on the market, including obsolete and discontinued models where new replacements are no longer available.

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Repair vs. Replacement

For most variable frequency drives, professional repair costs 40 to 60 percent less than purchasing a new unit — and significantly more than that for large-frame or medium-voltage drives. Beyond cost, new drive lead times from manufacturers can stretch to weeks or months, particularly for drives that are configured for specific applications.

A repaired drive is typically returned within 5 to 10 business days from receipt. Emergency turnaround is available when production cannot wait. The existing parameters and application configuration come back with the drive — there is no recommissioning from scratch.

For drives that are obsolete or no longer manufactured, repair is often the only practical option for keeping equipment in service without a full system replacement.

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Frequently Asked Questions

What is the difference between a VFD and an AC drive? A VFD and an AC drive are the same device — both control motor speed by varying the output frequency and voltage delivered to the motor. Other common names for the same technology include inverter, variable speed drive, and motor drive. The terminology varies by industry and region.

Can you repair a VFD on-site without removing it? Yes, in many cases. Our field technicians carry diagnostic equipment and commonly needed parts and can perform VFD repair in place when removing the drive is impractical or would extend downtime. Contact us to discuss your situation and we will recommend the fastest path to AC drive repair resolution.

How long does VFD repair take? Standard turnaround is 5 to 10 business days from receipt of the unit. Rush and emergency service options are available for critical production situations. We also provide DC drive repair.

Do you repair obsolete VFDs? Yes. Repairing a discontinued drive is one of the most cost-effective solutions available when replacements are no longer manufactured. We maintain parts inventories and technical documentation for legacy drives from all major manufacturers.

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Get a Quote

Whether your VFD is throwing fault codes, running erratically, or completely out of service, our team can help. Contact us for a free evaluation and no-obligation repair quote, or request service online.