Re: [CAD_CAM_EDM_DRO] Burned out drives
Posted by
R Rogers
on 2004-11-15 06:41:49 UTC
Ronald Anderson <ronaldsa@...> wrote:
FYI,
For all those reading about or experiencing burned out drives, the problems
as related, reveals several issues.
1.) Just because a drive is rated to 80 volts does not mean that you should
run it there.
///Mariss form Gecko stated that the Gecko 320 actually comes apart at 118 volts and 30 amps. 72 volts, if I recall correctly is what he recommends. That would be nice to run amps at half rated voltage however, many of us do not have that option. In a perfect world or one without budget restrictions we would order specially wound servo motors as an exact element of our control system. thats not the case, as used and surplus motors are the typical candidates. Large 40 volt servos are vitually non-existent. Then again, why would anyone want to run a CNC system at half speed for years trying to protect a $100 servo amp? when it would probably have been fine running twice the speed all the while.
Ron
The rating usually comes from the max rating of the
transistors being used. As an electronics designer I will never push a
device past 1/2 of the max rating just to give some reasonable margin to
the operation. Anything beyond the 80 volts is beyond the SOA (safe area of
operation, read the data sheets).
2.) Everyone running 48 volts is doing the right thing. With chopper drives
you can achieve the current required through the stepper windings without
resorting to max voltage.
3.) By running something like 48 volts then one can incorporate an active
power dump on the power supply, by using a comparitor and setting it to say
60 volts, the fet being controlled by the comparator can be turned on to
dump extra power into a power resistor anytime the power supply voltage
goes above 60 volts. Thus feed back power and spikes will not be a problem.
/// This would remedy power spike issues? If so, I'd like to know more about this as I have lost one Gecko in a year and a half operation due to voltage spikes. My Geckos are running at 64 volts.
Ron
If someone needs an active power dump device, send me an e-mail message off
the list.
Sincerely,
Ron
ronaldsa@...
www.bsio.us
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bill
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[Non-text portions of this message have been removed]
FYI,
For all those reading about or experiencing burned out drives, the problems
as related, reveals several issues.
1.) Just because a drive is rated to 80 volts does not mean that you should
run it there.
///Mariss form Gecko stated that the Gecko 320 actually comes apart at 118 volts and 30 amps. 72 volts, if I recall correctly is what he recommends. That would be nice to run amps at half rated voltage however, many of us do not have that option. In a perfect world or one without budget restrictions we would order specially wound servo motors as an exact element of our control system. thats not the case, as used and surplus motors are the typical candidates. Large 40 volt servos are vitually non-existent. Then again, why would anyone want to run a CNC system at half speed for years trying to protect a $100 servo amp? when it would probably have been fine running twice the speed all the while.
Ron
The rating usually comes from the max rating of the
transistors being used. As an electronics designer I will never push a
device past 1/2 of the max rating just to give some reasonable margin to
the operation. Anything beyond the 80 volts is beyond the SOA (safe area of
operation, read the data sheets).
2.) Everyone running 48 volts is doing the right thing. With chopper drives
you can achieve the current required through the stepper windings without
resorting to max voltage.
3.) By running something like 48 volts then one can incorporate an active
power dump on the power supply, by using a comparitor and setting it to say
60 volts, the fet being controlled by the comparator can be turned on to
dump extra power into a power resistor anytime the power supply voltage
goes above 60 volts. Thus feed back power and spikes will not be a problem.
/// This would remedy power spike issues? If so, I'd like to know more about this as I have lost one Gecko in a year and a half operation due to voltage spikes. My Geckos are running at 64 volts.
Ron
If someone needs an active power dump device, send me an e-mail message off
the list.
Sincerely,
Ron
ronaldsa@...
www.bsio.us
Addresses:
FAQ: http://www.ktmarketing.com/faq.html
FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@..., timg@...
Moderator: pentam@... indigo_red@... davemucha@... [Moderators]
URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
http://www.metalworking.com/news_servers.html
http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
bill
List Mom
List Owner
Yahoo! Groups Links
---------------------------------
Do you Yahoo!?
Check out the new Yahoo! Front Page. www.yahoo.com
[Non-text portions of this message have been removed]
Discussion Thread
Ronald Anderson
2004-11-15 06:01:47 UTC
Burned out drives
R Rogers
2004-11-15 06:41:49 UTC
Re: [CAD_CAM_EDM_DRO] Burned out drives