Depends on the full spec of the motor: 4.2A but at what coil voltage? If we assume a 3v coil rating (like all our motors, but thats not a given, check your datasheet) then: 4.2 x 3 = 12.6w x 2 coils - 24.6w per motor. Lets assume a 80% efficiency from the stepper driver, so lets add 20% to the base rating: 30w per motor at least 30w x 3 motors = 90 watt. BUT, that depends on the coil voltage. If its a 9v rated coil, you go up to 270w for example, so do check (or post here if you'd like us to check) the datasheet
Thank you for the reply, This all the information on the stepper motor. Not so sure if that voltage stated in the companies spec sheet is true This is the strongest Nema 23 stepper cnc motors, it with step angle 1.8deg and size 57x57x114mm. It has 4 wires, each phase draws 4.2A, with holding torque 3.0Nm (425oz.in). Electrical Specification Manufacturer Part Number: 23HS45-4204S Motor Type: Bipolar Stepper Step Angle: 1.8 deg Holding Torque: 3.0Nm(425oz.in) Rated Current/phase: 4.2A Voltage: 3.78V Phase Resistance: 0.9ohms Inductance: 3.8mH ± 20%(1KHz) Physical Specification Frame Size: 57 x 57mm Body Length: 113mm Shaft Diameter: Φ10mm Shaft Length: 24mm D-cut Length: 20mm Number of Leads: 4 Lead Length: 400mm Weight: 1.8kg
If you don't trust the values given, you can always check them with a little Ohms Law: I=V/R I = 3.78 / 0.9 3.78/0.9 = 4.2 And they claim 4.2A, so the two matches, makes me think even if they are lying, at least they made sure the math checks out (; So with that number: 3.78v x 4.2A = 15.876w per coil x 2 coils = 31.752w per motor x 3 motors = 95.256w (add some overhead for losses, lets call it under 120w, so the 350w will be great, running cool, long life expectancy, etc)