A high measurement indicates the motor has an open winding. It has a center tap for each phase, which can be used to change the wiring to supply current to the opposite half of each coil. The readings should be about 10-14% of the following values:Ī low measurement indicates the motor has a shorted winding. The Step Motor Specialists Stepper Motor Basics DIFFERENT WINDINGS Unipolar Unipolar winding has two windings per phase, and can reverse the magnetization of the stator coils without reversing the direction of the current. When one winding or set of windings is energized, it becomes an electromagnet with a polarity determined by the direction of current. This gives you the true resistance measurement. A stepper motor consists of a central rotor surrounded by a stator with some number of windings (see figure 1).
If you do not know how to zero your meter, take note of the resistance measured when the two leads are touched together and subtract that from the actual measurement.
IMPORTANT: Set the multimeter to the ohm scale and zero it out by touching the two leads together and pressing the appropriate button to zero your meter (see your meter instruction manual on how to do this). Each motor, regardless of the connector, can be measured this way. These can be used to measure the resistance. At the connector, you can see tabs where the pins are (see Figure 2 and Figure 3). Starting from either side, the first two wires are one phase and the remaining two wires are the second phase. To measure the resistance, disconnect the motor at the connectors (see Figure 1). This will be more useful than the video LED test in identifying the windings in, for example, centre-tapped uni-polar motors as each coils.
as i know the 4.2 A isnt the current i have to deliver to my motor to get the best torque because this current is per winding, it has to be 1.44. with 24 V power supply and an DM542T driver. The DC current in a winding needs to be reversed to reverse a magnetic pole and allow the motor to function. I am running here a stepper Motor Nema 23 with arduino and the following specification in the pictures. Resistance in the stepper motors is measured on the two phases. Bipolar stepper motors are a type of stepper motor with a single winding per phase and no center tap (unlike a unipolar stepper motor). The stepper motor consists of a rotor that is generally a permanent magnet and it is surrounded by the windings of the stator. Stepper Motor Resistance Test Stepper Motor Resistance Test