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Replacement stepper motor technical data - resistance of motor

Posted: Fri Nov 09, 2018 12:56 pm
by bobby
Hello good people of Tom's 3D.

I have to replace old stepper motor - but can't find exact the same model. (it's 20 years old now)

The old one parameters:
4 wires
1,4 A
1,8 degree step
0,6 Nm
Inductance 11 mH
resistance 2,55 ohm

The new one:
8 wires
1,4 / 2.8 A
1,8 degree step
1,4 (2-phase) Nm
Inductance 11,2 / 2,8 mH
resistance 3,4 / 0,85 Ohm

Of course if i plug it in series mode i will get: 1,4 A, 3,4 Ohm, 11,2 mH

There are two things that bother me:

I don't want to replace or reprogram drivers (strictly i am not able to do that)
First thing: will higher resistance make a difference (driver is Allegro A3955) ? I thought that most critical parameters are: current (1,4A), steps 1,8 degree, sufficient torque and inductunce (affect voltage). I am a bit worry i could burn motherboard of the device.

The second thing is: manufacturer of the stepper motor claims it's 1,4 A in serial mode and 2,8 A in parallel.
I always thought that there is 0,707 multiplier between serial and parallel mode of stepper motors. Am I wrong?
Again, I don't want to burn the driver.