Leadshine Mx3660 shunt regulator query

**the great waldo** · 08-05-2018

Hello All
I've just taken the plunge and bought a Leadshine MX3660 all in one box. The manual recommends using a shunt regulator/ capacitor to stop back voltage? blowing up the stepper drivers in an e stop situation. Does anyone know of the values of the capacitor required (48 volt switching power supply 3 x Nanotec ST6018L3008-A 4.3V 3.0amp stepper wired in parallel ) Or does any one have a circuit diagram of a shunt regulator that I could make. Also would it be better to use a non switching power supply transformer caps and rectifier ?
Thanks in advance

Cheers

Andrew

**JAZZCNC** · 08-05-2018

Originally Posted by the great waldo

Also would it be better to use a non switching power supply transformer caps and rectifier ?
Thanks in advance

Yes this is what you require. Switching PSU isn't recommended for CNC because the back EMF from steppers can cause you trouble with PSU protection shutting the unit down.
Toroidal transformer with caps & Rectifier is what you require for best operation.

**the great waldo** · 08-05-2018

Hi Jazz

Thanks for the reply. I read somewhere that a 4700uf Cap should be put across the + - volt out from supply. Would that be needed as well as with a non switching power supply or could that be part of the smoothing circuit in the psu maybe upping the values of the Capacitors. It's been years since I did much electronics stuff mainly audio projects from everyday electronics and electronics today mags !!

Cheers

Andrew

**JAZZCNC** · 08-05-2018

Capacitors are the smoothing/shunt circuit and the PSU output you require will determine the Capacitance required.
I think the MX3660 uses 60Vdc drives so you'll not want much more than 50V output and if using 4A motors you'll require aprox 8A output for 3 x motors(65% total amps).
So Transformer with 2 x 18Vac secondarys wired in series and 300Va will give you aprox 50V with 8.3A or if require more amps go with 500Va for just under 14A.
With 300Va you'll get away with 2 x 4700uf-80 or 100V Caps wired in parallel but for the little extra they cost I'd go with 3 x 4700uf to give that bit more smoothing.

25A or 35A Rectifier.

**the great waldo** · 08-05-2018

Hi Jazz

Thanks very much for the info. I had just checked out this transformer http://www.trafoshop24.de/rk-transfo...-rk-ec500.html Is there any benefit from using toroidial as opposed to the old square transformers from back in the day ?

Cheers
Andrew

**Doddy** · 09-05-2018

Originally Posted by the great waldo

Hi Jazz

Thanks very much for the info. I had just checked out this transformer http://www.trafoshop24.de/rk-transfo...-rk-ec500.html Is there any benefit from using toroidial as opposed to the old square transformers from back in the day ?

Cheers
Andrew

Advantages of toroidal transformers is pretty much weight, efficiency, reduced em field and, typically, cost. They come with a bit of a disadvantage of high-inrush current, but that can either be ignored or designed-out.

**Gary** · 09-05-2018

Leadshine makes a shunt regulator specificaly for this.
https://www.zappautomation.co.uk/sr5...regulator.html

You can use a switching supply with a stepper system, but they are not ideal, but if you do, use a nonregulated switching supply. like the sps type.

Originally Posted by the great waldo

Hello All
I've just taken the plunge and bought a Leadshine MX3660 all in one box. The manual recommends using a shunt regulator/ capacitor to stop back voltage? blowing up the stepper drivers in an e stop situation. Does anyone know of the values of the capacitor required (48 volt switching power supply 3 x Nanotec ST6018L3008-A 4.3V 3.0amp stepper wired in parallel ) Or does any one have a circuit diagram of a shunt regulator that I could make. Also would it be better to use a non switching power supply transformer caps and rectifier ?
Thanks in advance

Cheers

Andrew