I want to attach 2 series motors to 40V AC how much current do I need if each motor is 24V DC?
Less current as marked on motor, about much less than half. 40Vac needs to go through a bridge rectifier to change into DC before able to be used by DC motor. Output voltage as low as 36Vdc after that.
We have no idea - you don't give the power rating of the motors and of course there are losses in the rectification of the AC to DC
It won't work. You can't connect a DC motor to an AC supply. It will just sit there and eventually burn out.
Do you want to attach 2 permanent magnet DC motors in series across a 40 VAC source or do you have two series wound DC motors that you want to run from a 40 VAC source?
You will need to rectify the 40V AC to DC. If you use silicon diodes you will lose 2*.7 or 1.5 v so you will get ~ 38.5 volts Dc. If you use schottky diodes you will lose ~2*.345V =~ .7V and end up with ~ 39.3 volts. You will need a fairly large capacitor. You did not say how much current the motors need. Read the data plate on the motors. It will say they use 24 V @ X current. They need to use the same current. They should be the same motor model # to share current. You are compremising the motors because together they need 48 volts not 40. They will run slow.
