Power supply size

[dhaddox]

I am building a cnc router and I am using servos. There are 3 of them that have a continous stall current of about 6amps, the other is about 3 amps. They are 60v brush servos. The power supply I have has a 1000va transformer and about 30000uf filter capacitors. My question is do you think this will be a large enough power supply? Any help appec.

[marting]

Hi From my calculations you should be fine, although with 1000VA you are just above minimum requirement, I would opt for 1500VA in case you would need the power particularly with servos. The capacitor value should be fine, you have almost twice the required value (approx 1000uF / 1A current of the servos - general rule) which not an overkill but that just makes it more stable on sudden current demand. The only thing about capacitors make sure it ideal for such applications, particularly the rated operating voltage - do some research on the net or consult a supplier about this to guide you better. Transformer should be aprox 43.5V AC (working ..... {60 (Vdc) / 1.414 (rms of sine wave)}+1.2Vdc (voltage drop across rectifier) = 43.6Vac.
Hope this has given you some orientation.
Marting

[Al_The_Man]

You should design for a supply at least motor rated voltage +10% DC.
Power-Supply Considerations For Servo Amplifiers
Also a little known phenomenon is that when the current demand is near the rated motor current, a larger capacitor will actually increase the required VA rating requirement.
Al.