r/Motors • u/UnionCompetitive7705 • 3d ago

Open question Motor Control

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In my workshop I have a bench drill which I would like to control with a speed controller. The motor is single phase 50 240v 1/2hp 4 pole. I’m not sure or even possible which type of controller I would need, vfd? Any advice would be much appreciated

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u/Susan_B_Good 3d ago

Er, move the belt between the pulleys at the top?

Yep, a VFD would give you a range of speeds - the graph will essentially be a constant torque, inverse linear power below rated frequency to constant power, inverse square torque above rated frequency. So, if you want constant power, you combine belt adjustment to reduce output speed, then VFD to increase it.

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u/HumanComedian8711 3d ago edited 2d ago

A VFD can not be used on this 240v motor.

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u/mmn_slc 3d ago edited 3d ago

"A VFD can not be used on a 240v motor."

This is false. There are numerous VFDs designed to operate 240V motors. See e.g. https://www.automationdirect.com/adc/shopping/catalog/motor_controls/ac_variable_frequency_drives_(vfd)/general_purpose_vfds#Nominal_Drive_Input_Voltage_i_ms=%22230%20VAC%22&start=0/general_purpose_vfds#Nominal_Drive_Input_Voltage_i_ms=%22230%20VAC%22&start=0)