Power Supply Question (Possible AC bleedthrough)

[sdantonio]

Taking into consideration that I know nothing about electronics I have to ask what is probably another dumb question (actually I had to take an electronics course in grad school, but that was a long long time ago and it was a real sleeper, so I don't remember anything).

I have inherited a power one switching power supply Model spf4e2v6k. Rating is 28VDC, 27A (plus a whole host of other taps). It seems to be an obsolete number, they still make the spf4 series, but I can't find that particular model This is the best I could turn up on the web. http://rocky.digikey.com/WebLib/Powe...%20Catalog.pdf

I have it downstairs running now for a while and it seems to be pretty stable at 30VDC +0.2 /- 0.1 which is seems OK to me (but what do I know about electronics). When I switch the VOM to ACV I read 65.5VAC.

I intend to run it with gecko G202's and Pacsci powerpac steppers (N Series-
Standard, 1 stack , 665in-oz rated 65VDC wired in parallel). The parallel wiring should give me the equivalent of a 60VDC power supply wired in series.

Is this 65.5vdc normal behavior? Will it damage my gekodrives if I hook it up like this? Should I throw a bridge rectifier inline and will this get rid of the AC bleedthrough?

Thanks

[Al_The_Man]

Originally Posted by sdantonio When I switch the VOM to ACV I read 65.5VAC. The parallel wiring should give me the equivalent of a 60VDC power supply wired in series. Is this 65.5vdc normal behavior?

Testing a DC switching supply with an AC voltmeter, you are going to get all kinds of odd ball readings, you may be getting some switching pulses etc, which are misleading. Use the DC range only.
If you were to use a moving coil meter, in all probability you would get completely different results or none at all.
I am not sure what parallel wiring you are refering to to get 60vdc in series?
Al.

[sdantonio]

Is here a better way to test it? I could take it to work and let the EE's test it on the power supply tester if you think that would be a good recomendation. I just awitched it to AC to try and test it in every way possible that I have at home just to make sure it wasn't going to do anything funky when I hooked it up to things that matter.

This is the complete reference to wiring in parallel (The parallel wiring should give me the equivalent of a 60VDC power supply wired in series. could be a totally erroneous interpretation of the reference below on my part)

I have looked at a lot of stepper motor curves in the past, and for some Pacific Scientific units (I am running the Powermax II units) the torque is almost identical for both series wired and parallel wired at around 38 Volts DC. Anything 24 to 35 volts should be wired parallel. Above 35 Volts wire the steppers in series, Otherwise, the higher voltages with the motors wired in parallel will remove skin if touched, and de-magnetize and destroy the steppers.

I am running 48 VDC in Series, and the motors get so hot that I have to shut the system down after 3.5 hrs. of constant operation. Otherwise, they get so hot that they start missing steps. I won't recommend two 28 Volt power supplies in series (56V) from my own experience as it appears to be overkill. You should get very good results from the 28 Volt supply.

If you wire the motors in parallel at 28 VDC, The results should be almost the same as if they were wired in series at twice that voltage. Higher voltage above a certain point (about 38 Volts) only generates more heat from the steppers, since all excess power is dissipated as heat.

Thanks