Re: VFD Setting Help not much torque at low speeds.
Does your Huanyang VFD have sensorless vector capability? If so, you may need to turn on that function in the parameters. That should give you nearly a flat torque curve from 0 to 3600 RPM. If your VFD is V/Hz only then you will not get full torque at lower RPMs.
EDIT: If you replaced the motor, you chose the wrong one. The 3600 RPM motor is a 2 pole, an 1800 RPM motor is a 4 pole. The difference in the two motors is 11 Ft/lb of torque vs. 22 Ft/lb of torque. Most 1800 RPM motors in that HP range will run just fine at 3600 RPM, and are normally rated higher than that.
Jim Dawson
Sandy, Oregon, USA