Power Supply/Power Cord Sizing for Four 850 oz-in Servos, One is Slaved
Could someone please give me feedback on power supply and power cord sizing? This is an aluminum machine made to cut aluminum plate. It is in a residential building connecting to 240VAC but will be moved to “light industrial” commercial space in the future. Here are some details:
I have four 850 oz-in Keiling servos.
Continuous current: 7.5 amps
Peak current: 33.5 amps
I also have
Spindle: 15 amps (3-1/4 hp router)
My gantry is 3 ft. wide weighing 215 lbs. with two servos driving it. A servo is on each side with one slaved to the other. Calculated servo inertia ratio was less than 10, with a 2:1 toothed belt reduction.
Servo cable is rated at 41 amps.
Power Supply Sizing Problem:
For a 3-servo machine, I believe a general rule of thumb that others have used is to take the peak current draw, multiply it by 3 servos and take 66% of that.
My 4-servo total current calculation for power supply sizing is:
(66% x 33.5 amps x 4 servos) + ( 15 amp spindle motor) = 104 amps
I took 12 amps off because one servo is slaved. So, 92 amps still seems like way too much for a machine with a 200 lb gantry. Life experience is telling me it’s a 65 amp machine. I don’t think it will be stiff enough to handle deeper cuts anyway. Am I off track?
In any case, I have one 1500W, 19.5 amp Toroidal power supply. The data sheet states that it can easily handle 200% overload for a few minutes. I don’t know how they come up with the 19.5 amps since it varies inversely with the voltage. So, I was planning to run it with just one power supply while checking the toroid for heat buildup. I think two of these should be enough. That will be 39 amps continuous with 78 amps for a few minutes. What do you think?
Power cord sizing should then be 78 amps + 15 amp spindle = 93 amps. In my residence, I can only get 240VAC ,50 amps. So, I’ll be limited on depth of cut until I move it to a “light industrial” commercial space. Does this sound like I’m in the ballpark and like it's going to work okay for now?
Thanks!