[naveen.a019]

Hi, my doubt is if i am planning to run 3 stepper motors rated 1.5v 1A from the same power supply, do i have to choose a power supply of 4.5A output because of 3 motors or just 1.5A for all motors.

[emorning]

4.5 A for all the motors.

I think about electricity like it was water flowing through pipes.
A power supply is like a water pump, the voltage is a measure of the 'pressure' that the water(electricity) is pumped into the pipes(wires).

Current is a measure of the amount of water(electricity) that is being pumped.

A power supply will always pump electricity at its rated voltage and can pump an amount of electricity up to its rated amps.
So what you want is a power supply that can pump up to 4 amps of electricty at 1.5 volts.

After you select a power supply maybe you should post again just to make sure its appropriate.

[doorknob]

Generally you would add the current loads together to get the total current that would be drawn from the supply. However, in typical CNC applications, not all three motors are drawing full current at the same time, so you should be able to get by with a power supply that is rated at less than 3X a single motor's current draw.

Perhaps a rating of 60% or 70% of the maximum current draw of the three motors would be adequate, but that would depend on your specific application.

As far as the voltage rating of the power supply, typical practice is to use a higher voltage than the stepper's "nameplate" rated voltage, and regulate the current through the motor coils by using a "chopper" or other current regulating method to keep the current within the rated value. So, instead of looking for a 1.5 volt power supply, you would be looking for one rated for a higher output voltage, based on the electrical characteristics of the specific stepper motors that you plan to use and the current regulating characteristics of the stepper motor driver that you will use.

[naveen.a019]

Wow....that's easy to remember, thank you so much for your reply...and i will definitely post again once i run it. And by the way you would laugh at me if i would say i have already built 3 machines and the drivers myself and still keep's forgetting about the stepper motor current.

[James Newton]

emorning and doorknob are both right (or wrong) depending on the type of drive. If you use a linear or simple drive, then the current is additive and 4.5 is the correct answer. If you use a chopper, then you get the percentage discount.