I bought an old drill press tnw super condor 30l but the motor smoked because of the rotary cam switch is broken. The drill is old and the motor have no motor plate but few engraved numbers 380 and 20 the others can't be read, I can't find the rotary cam switch. The company that made them cannot be found "brevetti ergo italia", it was 500v/5.5hp (that's what i remembered i lost the paper that describe the rotary cam switch technical details, i remember and a number I12.07) rated rotary cam switch.

So i was thinking if it is possible to replace the rotary cam switch with a VFD. I read on one post that say's using VFD will make the motor give half of its torque, i can live with that as long it works

Edit: The motor is 2 speed motor

  • \$\begingroup\$ Please punctuate and capitalise your writing properly in both the title and the post. This is a mess. \$\endgroup\$ – Transistor Dec 14 '18 at 17:27
  • \$\begingroup\$ sorry not my first language \$\endgroup\$ – Zak Dec 14 '18 at 17:39

You need an electrician to install and verify this will work.

32A/660V 12 Terminals latching (1-0-2)


enter image description here

My guess is this is what you have. enter image description here

But how do you know the motor is still good?

  • \$\begingroup\$ Got the winding completely rewired. \$\endgroup\$ – Zak Dec 15 '18 at 5:48
  • \$\begingroup\$ So do you want a switch or a VFD and a wish that it works at low speed with high torque loads, You still need pulleys \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Dec 15 '18 at 7:08
  • \$\begingroup\$ I want to install a VFD. i know that i still need pulleys, will put the belt on top speed and then change the speed from VFD. what i was trying to say how to wire the 2 motor speed with VFD. \$\endgroup\$ – Zak Dec 15 '18 at 17:32
  • \$\begingroup\$ The VFD can supply constant max torque vs speed by adjusting V/f but the pulleys are inverse torque vs speed for same power. so if using a 30mm drill vs a 3mm drill you will get only 1/10th the max torque at max pulley speed or like starting a bike in 10th gear. Generally you want more torque at lower speeds, not 1/2 the torque \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Dec 15 '18 at 18:20
  • \$\begingroup\$ does that mean even if i setup the VFD i have to change the belt for every drill bit ? \$\endgroup\$ – Zak Dec 16 '18 at 18:07

If you cannot read the information on the motor nameplate, how can you buy the correct VFD for it? I would opt for trying to replace the switch.

  • \$\begingroup\$ does any switch work for it ? \$\endgroup\$ – Zak Dec 15 '18 at 5:49
  • \$\begingroup\$ i was opting to buy a higher spec VFD and try my luck with it \$\endgroup\$ – Zak Dec 15 '18 at 5:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.