Thread: My new Hercus 9C and 3 phase.

Those motors are almost certainly a Y (well my 1966 Cadet motor was) and if you run it from a 240V VFD you will only get half the power.
The motor can't be reconfigured at the junction box into a ∆ and has to be doctored inside to make it a ∆

Your alternatives are
1) do nothing and only get half the power at 240V 3P
2) take it to a rewinder to get converted (i.e. $$) or DIY
3) Get another motor.
4) You could get a 1HP Y or a half HP ∆ but remember that if you want to use the variable speed then at 25Hz it will only provide half the power.
If you decide to change the motor and want an improved full power speed range Id suggest getting a bigger motor.
I'm using a 1HP 240V ∆ connected motor on my Hercus.
2HP would still give you a full half HP at 12.5Hz, going lower than this may give you motor cooling issues.

One you have selected the motor then choose a suitable VFD.

Thanks BobL,
Yeah was cruising Ebay today and priced up a 1.5kw (2hp) motor 240/415 3 phase for $70 which would suit a cheap Chinese VFD which are $105.
So for half the cost of a 415v converter i get the benefits of vfd and a more powerful motor.
Now to pull out the old motor and measure the shaft.

i have converted several lathes and mills to work off vfd its not too hard ( once you work out how to set the parameters) just follow the circuit diag that comes with your vfd for switch connections . the switches you already have will do the job . you can probably remove all the excess gear in the cabinet to make room for the vfd, from memory the transformer was used for 32 volt light and the rest for interlocks or what ever .
pulley size unless your anal about it isnt too important because you can change speed of motor with vfd to compensate
gears try mal @ australian metalworking hobbyist
john

usual disclaimer get a sparky if your not confident with the leccy bit

Originally Posted by Mightypns

Thanks BobL,
Yeah was cruising Ebay today and priced up a 1.5kw (2hp) motor 240/415 3 phase for $70 which would suit a cheap Chinese VFD which are $105.
So for half the cost of a 415v converter i get the benefits of vfd and a more powerful motor.
Now to pull out the old motor and measure the shaft.

My recommendation, for what it's worth, is 2hp is too big. The "C" model machine was supplied with a motor of 1/2hp-3/4hp you could stretch to 1hp. Overpowering a machine is a dangerous practice. all's good while nothing goes wrong but should you have a problem "things" will break.
Mal