How to rectify a rotary converter to output 145V DC ?

[Joe_Leen]

Hi,

I need some direction on rectifing the output of my rotary phase converter to give 145V DC.

I have a Bridgeport Series II Interact II which I'm about to do a retrofit too and want to keep the original servos. So need to power them.

Appreciate and help,

Thanks,

Joe

[Al_The_Man]

Are the present drives 3 phases SCR type? If so I would be wary of using them on a RPC.
If PWM, then you probably only need to build a sufficiently large enough 1 phase supply.
Al.

[Karl_T]

You don't want to rectify without going through a transformer to provide isolation. If you don't use a transformer, you can't tie DC- to ground. Not a good plan.

Fet a single phase tranformer to 100 VAC, then a bridge rectifier, and electolytic capacitors. Plans have been shown on the zone several times

Karl

[Al_The_Man]

It also depends on whether you are keeping the existing drives, if so what type are they?
Al.

[Joe_Leen]

Plan is to use three Dugong servo drives in conjunction with the original SEM servos (145V, 35 Pulse Amps).

http://www.cnc4pc.com/Store/osc/prod...roducts_id=290

Karl can you direct me to one of the threads your referring to.

Thanks!

[Al_The_Man]

Well you only need to put a suitably sized transformer bridge and capacitor supply across the 240v 1 ph supply.
With a RPC, the load is going to be on the 240 1ph anyway.
Pulse amps are the ultimate maximum current the motor can carry momentarily without damage or demagnetization of the motor.
Your constant torque amps are most likely around 17~20Amps.
Here is a couple of recent posts, but the electronics forum search should show alot more.
http://www.cnczone.com/forums/genera...er_supply.html
http://www.cnczone.com/forums/gecko_...ive_these.html
Al.

[Karl_T]

Originally Posted by Joe_Leen Plan is to use three Dugong servo drives in conjunction with the original SEM servos (145V, 35 Pulse Amps). CNC4PC Karl can you direct me to one of the threads your referring to. Thanks!

Power Supplies

[Joe_Leen]

The reason behind the Dugong servo drives, I was reading a post by Simon Rafferty on the Mach 3 forum ...

"I had a chat with the makers of the Gecko, who very kindly suggested that something bigger such as the Dugongs would be a more sensible option"

So this is why I also am going to go with the Dugong. Simon was also converting a Bridgeport with the same servo motors. I have mailed him and asked him how he powered them.

Just found this thread ... http://www.cnczone.com/forums/viper_...ly_design.html

Al you suggested this PSU for the exact same servo motors:

"Ball park P.S. for all three motors, you will need a 1.5Kva transformer (240/120 isolation transformer), 50amp bridge rectifier 350PIV, 33,000µf Capacitor 250vdc rating.
Al."

The builders isolation tranformers we have over here in Ireland are 220V / 110V 5Kva. If one of these is used will it make a large difference to the required capacitor rating ?

Thanks for all the help !

[Al_The_Man]

Oversizing the transformer is not a problem, just a little less economical.
It does not affect the capacitor sizing.
Al.

[ETChipotle]

Originally Posted by Al_The_Man Are the present drives 3 phases SCR type? If so I would be wary of using them on a RPC. If PWM, then you probably only need to build a sufficiently large enough 1 phase supply. Al.

Could someone clarify this statement for me? Forgive my lack of knowledge about drives at this point. I have a Bridgeport Interact I mk2 mill (from an auction last week). It has the SEM 155 1205 Servos for xyz, and it has a SICME Motori spindle motor. There are boards in the cabinet that say KTK, so I assume I have thyristor drives. Is this what you mean by SCR drives? And if so, what would you recommend for converting power for it from USA residential 220 VAC?

I'm trying to think through a plan for this mill, including how to power it.

Another note closer to the original question in this post: the axis motors say 145V, so I was looking to see how to get a transformer that's 220AC input and 100VAC output. Square root of 2 times 100V is a minor bit under 145V. The first transformers I found that meet this description are for using Japanese equipment in the USA, and they're available up to 2000watt, but I don't know if this is appropriate.

[Al_The_Man]

If the present drives are fed with 3 phase and no large transformer with a bridge and capacitors, then they most likely are SCR/Thyristor drives.
If you do have a ~2kva transformer feeding them with a bridge and large electrolytic caps then you should be able to resuse the supply.
If you do need a transformer, then you can use a 240/120 1 ph and add a bridge an caps.
120 will give you around 170DC, this is normal to use a power supply at least 10% higher than the motor rated voltage.
It appears KTK ARE SCR drives.
Al.