Common PowerFlex VFD Issues and How to Resolve Them

Variable frequency drives (VFDs) — like Allen-Bradley’s PowerFlex series — are made to optimize motor performance and improve efficiency, extending the lifespan of your equipment. But when they start acting up, productivity takes a hit. Diagnosing and fixing VFD issues quickly is the difference-maker between a minor hiccup and a full-blown disruption. Here’s a breakdown of common PowerFlex VFD problems and how to get your system back on track.

Problem 1: The drive won’t start

A non-responsive VFD can bring your operations to a standstill. But before assuming the worst, it’s important to approach the problem with a minimally invasive mindset. Check these areas first.

• Power supply issues. A tripped breaker or blown fuse can keep the drive from powering up. Verify incoming voltage and reset if necessary.
• Incorrect parameter settings. If the VFD has been reprogrammed or reset, some parameters may not be aligned with system requirements. Cross-check configuration settings against manufacturer recommendations.
• Fault codes and alarms. Most PowerFlex drives display fault codes when something goes wrong. Checking these error messages can often point you directly to the problem.

Problem 2: Overvoltage and undervoltage faults

Power issues are among the most frequent VFD problems. Voltage fluctuations can trigger automatic shutdowns to protect the system, but repeated faults indicate a larger issue. Here’s what to look for:

• Overvoltage. This usually happens when a motor is decelerating too quickly, sending excess energy back into the drive. Adjusting deceleration times or adding a braking resistor can help absorb excess voltage.
• Undervoltage. If input voltage drops too low, the drive may shut down to prevent damage. Check incoming power levels and ensure proper wiring connections. Sudden undervoltage faults could also indicate an unstable power source.

Problem 3: Overheating and thermal trips

Like any electronic device, a VFD generates heat. Too much of it can shorten component lifespan and lead to unexpected shutdowns. Proactive cooling keeps VFDs running efficiently and reduce the risk of heat-related failures. Look for:

• Blocked or dirty cooling fans. Dust buildup restricts airflow, causing the drive to overheat. Clean vents and ensure fans are working properly.
• High ambient temperatures. If the drive is installed in a hot environment, you’ll need to take extra cooling measures like ventilation or air conditioning.
• Excessive load. A motor operating beyond its rated capacity will force the VFD to work harder, generating more heat. Ensure the system isn’t overloaded.

Problem 4: The motor isn’t responding correctly

Sometimes, the VFD is running, but the motor isn’t behaving as expected. If performance seems off, a few targeted checks can pinpoint the issue:

• Loose or damaged wiring. Inspect connections between the drive, motor, and control system. Even a minor disruption can lead to erratic performance.
• Parameter mismatches. Speed, torque, and acceleration settings must match the motor’s design. A misconfigured drive may not deliver the right output.
• Interference or noise. Electrical noise from nearby equipment can disrupt VFD signals. Using shielded cables and proper grounding helps maintain signal integrity.

Give VFDs the attention they need

If basic VFD troubleshooting doesn’t solve the issue, you need deeper diagnostics and professional support. Throughout the month of February, GES is offering 10% OFF single repairs or 15% OFF 3+ repairs of Allen-Bradley products — including PowerFlex VFDs!

Expert PowerFlex repair solutions when you need them

Even well-maintained drives can run into trouble. When that happens, fast and reliable repairs keep downtime to a minimum. At GES, our expert technicians diagnose and restore PowerFlex VFDs with precision and efficiency. Whether it’s a fault code, power issue, or full drive failure, we get your equipment back to running at full capacity — quickly and reliably.