Designer69
Senior Member
Folks, if I can recall correctly I believe I heard once that DC motors do not have current inrush.
Is this truth or pure nonsense?
Thanks!
Is this truth or pure nonsense?
Thanks!
If you directly apply rated voltage, the instantaneous current is very large.Folks, if I can recall correctly I believe I heard once that DC motors do not have current inrush.
Is this truth or pure nonsense?
Thanks!
DC motors do not have current inrush.
And the DC inrush current should be the DC resistance divided into the applied voltage. Once the motor is spinning it generates a back emf which reduces the current draw.
110222-1817 EST
Designer69:
You need a fundamental understanding on how a DC motor works, then you will be able to answer this question and a number of others.
So maybe the correct question to ask is how does a DC motor work?
.
The inductance will slow the rate of rise of current - a little.There is some inductance there also. Would it be enough to limit the current until the motor gets moving?
Mechanical DC starters ( don't know about solid state ones) had resistors in series with the armature. The resistors limited current to the armature circuit. As the motor increased speed the resistors were shorted out by contactors in parallel with them. The resistors were usually shorted out by timing relays.
I think you're right. There is an R L time constant I didn't consider.There is some inductance there also. Would it be enough to limit the current until the motor gets moving?
Folks, if I can recall correctly I believe I heard once that DC motors do not have current inrush.
Is this truth or pure nonsense?
Thanks!