The VFD Keeps Tripping

A variable frequency drive (VFD) that trips is doing its job. It saw something outside a limit and shut the motor down before it damaged the motor, the drive, or the machine. So the first mistake I see at 2am is treating the trip as the problem. The trip is the drive telling you something. The fault code is the drive telling you what it saw. Your job is to read what it saw, figure out why it saw it, and fix the cause. Not to reach into the parameters and widen the limit so the drive stops complaining. That last move gets motors burned and, on a bad day, gets a coupling let go with someone standing next to it. This guide is organized by fault class, because that is how the drive thinks and that is how you should work it. Overcurrent means one set of things. Overvoltage means a different set. The code narrows the search before you ever pick up a meter. What follows works across sectors, whether the drive is on a conveyor, a pump, a mixer, a fan, or a blower feeding a digester. I will flag where a corrosive or gas plant changes the answer.

Before you touch anything: read the log Every modern drive keeps a fault log with a timestamp and, on most platforms, a snapshot of the conditions at the moment of the trip. That snapshot is the single most useful thing on the machine, and most people walk right past it. Before you change one parameter, pull the log and answer these: What is the exact fault code, and what does the manual for this drive family call it? Codes are not universal between manufacturers. F005 on one brand is not F005 on another. What was the drive doing at the trip? Accelerating, decelerating, or running at steady speed? Overcurrent on accel and overcurrent at constant speed point at different causes. Was it loaded? Look at the output current and torque in the snapshot if the drive stores them. What time did it trip, and is there a pattern? A drive that trips every afternoon in July is telling you about ambient heat. A drive that trips when the line startup sequence energizes three big loads at once is telling you about line sag. A drive that trips right when an overhead crane runs nearby is telling you about noise or line disturbance.