| Stepper motors and servo motors have some | | | | can be performed using a standard multimeter or a |
| similarities and many differences. In general, stepper | | | | megohmmeter if one is available. |
| motors are controllable in steps without feedback | | | | First, disconnect and label the motor cable at the |
| whereas servo motors require a feedback device to | | | | motor junction box. Each wire on the motor can then |
| make adjustments accordingly. Troubleshooting these | | | | be checked for continuity to ground using a standard |
| two staples of industrial machinery is not all that | | | | ohmmeter. Each wire should read infinite or at least |
| complex when you have a basic understanding of | | | | 100,000 ohms at a minimum, anything below that |
| electricity and some proficiency using a multimeter. A | | | | reading or a direct short to ground would indicate a |
| general familiarity with motors and their operation and | | | | failed winding. Be sure to make a good clean |
| design is an added advantage as well. Stepper | | | | connection on both the motor wire and ground lug or |
| motors and servo motors can be found in virtually | | | | case of the motor. Repeat this test with a |
| every industrial environment these days. The | | | | megohmmeter is one is available. |
| complexity of industrial machines and the modern | | | | To check for continuity between the windings, you |
| controls that make them so efficient usually feature | | | | will need to set your ohmmeter to its lowest scale. |
| a servo motor or stepper for some type of motion | | | | There should be continuity between all three |
| control. Mechanical ratchets and gears, as well as | | | | combinations of wires (T1 & T2, T1 & T3, |
| human guided movement have long been replaced by | | | | T2 & T3) that reads in the area of 0.3 to2 |
| these precision motors. | | | | ohms. A reading of 0.0 ohms would indicate a short |
| Before beginning any troubleshooting of industrial | | | | circuit and and infinite or a reading of at least 1000 |
| equipment, the maintenance personnel or the | | | | ohms would indicate an open winding, hence a failed |
| individual responsible for troubleshooting and repair | | | | motor. |
| should take all steps required to ensure his or her | | | | Motor containing brushes can be visually checked and |
| own safety and the safety of those in the area of | | | | the commutators cleaned when necessary. Brush |
| the machinery. Proper lockout, tagout, and verification | | | | dust can be carefully blown out of a dirty motor |
| that the machine is energy-free is the responsibility | | | | using compressed air. This may even help alleviate a |
| of everyone involved in the troubleshooting. | | | | resistance reading to ground during the short test. |
| First we need to remember that the motor is just | | | | Overall, the basics of servo motors and stepper |
| one part of a motion control system. Once you have | | | | motors are much the same as a standard motors. |
| verified that the rest of the system is functioning | | | | Testing is also similar yet the name servo or stepper |
| normally, you can then proceed to determine if the | | | | can sometimes intimidate even a seasoned electrician |
| motor has failed using a few simple tests. These test | | | | or maintenance technician. |