Power Supplies Again

[tintruder]

Well, I received my 2030 drives and motherboard and I'm excited to get things going with the Sanyo Denki P5 400W motors.

But I still need a power supply.

I can easily build a couple 37.5v 9A regulated supplies...can I just hook 2 of them in series to get 75v? Is this wise?

I am also considering just rectifying 110vac to get 80v (110 x .707)and add enough nice big caps to keep it pretty smooth. Any reason why this wouldn't work? (I realize I am not isolated from the line voltage)

I'm having a tough time finding anything in Torroid transformers which would give me 80vac after rectification and smoothing, and there don't seem to be any regulators that are rated anywhere over 37vdc.

Should I use regulation?

Should I skip torroid transformers and just use regular iron-core types?

Do you use same VA rating for both types of caps? I'm looking towards about 1.2KVA for 3 motors.

How are other users of the 2030s or other Rutex drives powering their P5 motors? Are you simply accepting lower voltages? If so, how low is still adequate? Would 60VDC be enough?

I could also use a refresher on how much capacitance to add. Right now, I have three 350vdc 2200uf caps, but am thinking I really may need a couple more.

HELP???

Tom

[rutexus]

Tintruder,

See comments below.

Tom Eldredge
Rutex LLC


Tintruder said:

But I still need a power supply.

I can easily build a couple 37.5v 9A regulated supplies...can I just hook 2 of them in series to get 75v? Is this wise?

No need for regulated supplies. Don't use the supplies you mentioned above. Get a reasonably priced torroid from Avel Lindburg in Connecticut. They have a good selection for a reasonable price. A 60 volt transformer should work if you do not choose a much larger transformer than you need. (60 * 1.414) minus about .75 volts = 84 volts. That should be ok. The output voltages of transformers are rated at the current they are also rated for. In other words, if you buy a transformer rated at 10 amps and only load it at 5, it will put out more than its rated voltage. For a typical three axis cnc machine you can figure the load of two motors running continuously. Don't go higher in amps than that figures.

I am also considering just rectifying 110vac to get 80v (110 x .707)and add enough nice big caps to keep it pretty smooth. Any reason why this wouldn't work? (I realize I am not isolated from the line voltage)

NEVER, NEVER, Never use wall power without isolating it with a transformer. NEVER. Never....For your safey and the safety of your equipment.

I'm having a tough time finding anything in Torroid transformers which would give me 80vac after rectification and smoothing, and there don't seem to be any regulators that are rated anywhere over 37vdc.

Should I use regulation? Do not use regulation.

Should I skip torroid transformers and just use regular iron-core types? Either type is fine.

Do you use same VA rating for both types of caps? I'm looking towards about 1.2KVA for 3 motors.


Buy capacitors that are rated for a higer voltage than you need. The large electrolitic types that are suitable are rated in WVDC, working voltage DC.

You need 1000 uf per each amp you expect to draw. Don't skimp on capacitors.

A simple diagram of a suitable power supply is on the Rutex.com web site under 2000 series products, "motor and drive matching."

I think you should read the document carefully.

How are other users of the 2030s or other Rutex drives powering their P5 motors? Are you simply accepting lower voltages? If so, how low is still adequate? Would 60VDC be enough?

I could also use a refresher on how much capacitance to add. Right now, I have three 350vdc 2200uf caps, but am thinking I really may need a couple more.

HELP???

Tom[/QUOTE]


Tom Eldredge
Rutex LLC

[tintruder]

Thanks for the advice.

One question remains...by a 60V transformer, do you mean a 60+60 secondary, or a 30+30 secondary.

I'm looking at http://avellindberg.com/transformers...ange_specs.htm and was thinking of either the Y236951 or Y236959...just need to know how to interpret the secondary specs with respect to your advice.

I guess I do have one more question though...does Avel Lindberg sell direct, or do I need to find a retailer who carries their products? (suggestions who?)

At least I was pretty close with the capacitor selection!



Tom

[rutexus]

Tintruder,

You can choose which ever way you want to wire the transformer. When you make a 60 volt transformer with 2 thirties, you keep the current the same as they rate it. When you add two 60's in parallel you wind up doubling the current because each coil adds its current carrying capacity. It is just like adding flashlight batteries together. Two 1.5 v batteries will provide more current capacity than one AAA 1.5 volt battery. Which ever way gets you the current you need is fine. It's your choice.

They will sell direct to you. Also, tell them Tom at Rutex sent you to them.

Tom Eldredge
Rutex LLC

[tintruder]

Tom,

Avel sent me a price and when I told them you referred me, they added $20 to it!!!

Just joking!

They replied quickly and their price is actually better than I expected. Awaiting a few more quotes then I guess I'll start building the power supply!

Thanks for the help.

Tom