Allin1DC Baldor 150VDC Servo Voltage Question

[BartakamosRex]

Hi, Everone

I’m new to this forum and have just started a new conversion project.

I have a question regarding voltage step down for Allin1DC servo driving.

I have an RB-1 bed mill that I am converting to an Allin1DC and was wondering whether overdriving the servos a little is OK. I don’t really want to step down the 115V AC by any increment of transformer that I am able to find. I saw that someone had mentioned taking some wraps off a transformer, but if some additional voltage is tolerable for the servos I would just as soon leave it as is.

Servos are 150VDC max and the Cap Board from Centroid will produce somewhere between 163 and 168VDC based on the range of 110VAC power in my shop. So, without any step-down of the AC prior to rectification, I would be over-driving the servos by somewhere between 9 and 12 percent. Is this OK?

I don’t really want to sacrifice top speed or get into making a custom transformer if it’s really insignificant.

Let me know your thoughts on this. Thanks!!

Gabriel

[tblough]

They are labeled 150VDC MAX for a reason.

[xr4x4ti]

They are labeled 150VDC MAX for a reason.

What is that reason?

I am NOT a CNC expert. I have only installed a single Allin1DC. But I am an engineer that has used, specified and tested motors for my whole career in the products I designed. I now work for a company that makes electric motors. IMHO they will work just fine.

What is much more critical from a safety/heat, etc standpoint is the current. Since the motors will be driven by a smart control that will regulate the max speed and current, this should not be an issue. I can't believe that the windings can't handle a 10% over voltage. The ONLY reason it would be an issue is for some reason the motor winding were made with a wire that had a break down voltage that was really close to 150VDC. Once again, this seems very unlikely. I would use them the way they are before I would start making some Frankenstein transformer, that is more dangerous.

This is my opinion, use at your own risk.

Tim

[tblough]

As an Engineer as well, I wouldn't just assume the 150 max rating was arbitrarily assigned. If it can handle 10% over voltage then why didn't they assign a 160VDC max voltage? It's your motor. If you want to gamble that it can run at a higher voltage, run it at the higher voltage. If you decide your want to run it at the max rating or below, you don't need a Frankenstein transformer. You can easily purchase a transformer on eBay to do the job. Centroid has been selling systems for years with a transformer with any problems reanimation or otherwise.

[BartakamosRex]

As an Engineer as well, I wouldn't just assume the 150 max rating was arbitrarily assigned. If it can handle 10% over voltage then why didn't they assign a 160VDC max voltage? It's your motor. If you want to gamble that it can run at a higher voltage, run it at the higher voltage. If you decide your want to run it at the max rating or below, you don't need a Frankenstein transformer. You can easily purchase a transformer on eBay to do the job. Centroid has been selling systems for years with a transformer with any problems reanimation or otherwise.

As a non-engineer I know that generally Engineers are a fairly prudent and mostly pretty conservative bunch. I also know that typically product engineers design things with some pretty robust safety factors. I also know that EE’s anticipate that mains power has a margin of error of within +- 10% depending on your utility/generation equipment.

Was really hoping for some real-world feedback like, “Oh, yeah; I’ve been running this kind of setup for several years with no issues” or “DON’T DO IT— YOU’LL START A FIRE!”. Short of that I do also enjoy hearing other opinions on the matter as well— so thank you for that.

I would love to just buy a transformer that gets me in the right range but I would need a transformer to get me to a voltage of 106VAC prior to rectification. I have 120VAC single or 208VAC 3-phase as a starting voltage. I looked high and low for a transformer that would get me in that range. If you know of something that I missed, please send me a link.

Thanks, Again!!

[BartakamosRex]

[quote=tblough post_id=46553 time=<a href="tel:1613655390">1613655390</a> user_id=528]
They are labeled 150VDC MAX for a reason.

What is that reason?

I am NOT a CNC expert. I have only installed a single Allin1DC. But I am an engineer that has used, specified and tested motors for my whole career in the products I designed. I now work for a company that makes electric motors. IMHO they will work just fine.

What is much more critical from a safety/heat, etc standpoint is the current. Since the motors will be driven by a smart control that will regulate the max speed and current, this should not be an issue. I can't believe that the windings can't handle a 10% over voltage. The ONLY reason it would be an issue is for some reason the motor winding were made with a wire that had a break down voltage that was really close to 150VDC. Once again, this seems very unlikely. I would use them the way they are before I would start making some Frankenstein transformer, that is more dangerous.

This is my opinion, use at your own risk.

Tim
[/quote]

Thanks for your opinion— this was my feeling as well. I think if I don’t find a transformer, I might give it a try with some spare servos that I have at the shop.

[tblough]

How about something like this: https://www.larsonelectronics.com/produ ... ps-50-60hz

16V drop should be enough ~ 145VDC.

[cncsnw]

The buck/boost transformer is probably the cheapest option, and should work just fine.

Another option, since you have 208VAC, would be to use a transformer than nominally steps single-phase 240V to 120V. These are extremely common. I won't say "dime a dozen", because when you price one out that has the necessary capacity (maybe 2KVA) it is going to be two or three hundred dollars. If you supply such a transformer using two legs of your 208VAC, you should get about 104VAC on the secondary.
https://www.automationdirect.com/adc/sh ... /c1f002les

[BartakamosRex]

How about something like this: https://www.larsonelectronics.com/produ ... ps-50-60hz

16V drop should be enough ~ 145VDC.

I looked at a Larson that was similar to that, but actually was a step down from 115VAC to 105VAC but didn’t seem large enough— I think it was only about 13A rating.

Didn’t think or using a step-up transformer and connecting it the opposite way— would this still be rated at the same Amperage if I am using it in that way?

Thanks for your help!

[BartakamosRex]

The buck/boost transformer is probably the cheapest option, and should work just fine.

Another option, since you have 208VAC, would be to use a transformer than nominally steps single-phase 240V to 120V. These are extremely common. I won't say "dime a dozen", because when you price one out that has the necessary capacity (maybe 2KVA) it is going to be two or three hundred dollars. If you supply such a transformer using two legs of your 208VAC, you should get about 104VAC on the secondary.
https://www.automationdirect.com/adc/sh ... /c1f002les

I thought of that, but I didn’t want to buy an expensive transformer to find that it wasn’t supplying enough voltage. I wasn’t sure what the calculation is to figure that out— is it just as simple as applying the percentage?

Thanks for this idea as well!!