ERR 40 Overload on 1 hp VFD Running 0.75 hp Motor

Hello everyone,

I’m trying to get these drives to work with my motors, but having no luck. I’ve changed some parameters in the 1 hp VFD (Model: EM15-SP1S1-d75), but the motor shaft only shakes slightly when I try to run it. The drive sounds normal, but it doesn’t seem to have enough power to turn the shaft.

I did check, and the pump shaft turns freely by hand. I’m sending a 0–10 V signal on AI1 and using DI1 for start/stop. Has anyone run into this before, and could you share the correct parameters to get these motors running?

Leocadia wrote:Hi Leocadia,
The ERR 40 fault is an overload error. Your 0.75HP (0.55kW) single-phase motor has a rated current of 5.3–5.86A at 230V, while the VFD model you purchased (EM15-SP1S1-d75, 0.75kW) only supports 4A rated current. Since the motor current rating is higher than the VFD’s capacity, this leads to overload.
Usually, the capacity of the VFD is greater than the capacity of the motor, so we recommend a 3 hp VFD to match your motor. Please see spec on: https://www.ato.com/3hp-vfd-single-phase-120v-input-1-phase-3-phase-220v-output

Thanks for the quick reply. I didn’t expect this to be an amp issue since the VFD was showing 13A before it tripped with ERR 40.

Leocadia, I ran into something similar with a 1 HP pump motor. Even though the motor plate said 5A, the startup current was way higher. A small VFD tripped every time. I ended up going with a bigger drive (2x motor capacity), and it worked fine. I’d suggest trying the same.

Leocadia wrote:Since your motor’s rated current is already greater than the rated current of the VFD, the overload trip is expected. You may send us a video for further confirmation.
As a test, disconnect the motor from the VFD and check if the drive runs normally with no load. If it does, then the issue is simply that the motor draws too much current and the VFD cannot start it properly.

Hi, I'd like to say that before buying a bigger drive, double-check your parameter setup. Make sure the motor parameters (rated voltage, frequency, current, power) are entered correctly into the VFD. Also, look at the acceleration time—if it’s too short, the VFD might trip on overload during startup. Sometimes, just extending the ramp-up time fixes the shaking issue.

Appreciate all the feedback! I’ll first try adjusting the parameters and ramp-up, and if that doesn’t solve it, I’ll move up to a larger VFD as suggested.