AC Filter Before DC Power Supply

S

Sierevello

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I have a 36v DC power supply I am using to power a few steppers. Should I use an AC line filter on the incoming AC line power before the DC power supply just to be safe and assure the DC supply is getting the cleanest AC power possible and to alleviate any noise?

Thank You,
Steve
 
If you are talking about power conditioning, reducing spikes and noise into the supply, then I would only worry about it if you have had problems with other electronic equipment due to power problems. The stepper drivers and steppers are not particularly sensitive to the small glitches that might show up on the output of the power supply. Power supplies that are made today typically have input filtering (EMI/RFI) and surge protection (MOVs). The input filtering is aimed mainly at keeping the noise produced by the power supply from propagating onto your power line. (I'm assuming that your power supply is a switch-mode power supply. Is it a SMPS or is it a linear power supply?)
 
I'd be more concerned about keeping DC wiring away from AC wiring. The DC power supply is converting (rectifying) AC to DC and filtering it in the process. But after AC can pollute the cleaned up DC if routing of wires is poor. AVOID parallel runs of AC and DC. If AC must cross a DC line do so at a right angle. Twisting AC +- wires reduced induced AC hum. Shoving them into the corner of a metal enclosure also helps.

^^^ I'm drawing from the vacuum tube guitar amp world here where AC induced hum surfaces out the speakers. I have had amps that had a loud obnoxious AC hum go silent simply by re-routing the AC and DC wiring properly.
 
I'd only consider doing that if the supply was for something that would be sensitive to low-level noise-- audio preamplifiers come to mind here. But I also wouldn't use an SMPS for that kind of application.

For running stepper drivers ----- naah. The stepper drivers probably will emit more EMI than what's coming in on the SMPS anyway.
 
Stepper drivers are a noise source, but not sensitive to noise themselves. The only reason for an AC filter in your case would be to keep the noise *from* the stepper driver going back through the DC power supply and from there into your home/shop wiring to other devices like audio amps.
 
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