2. Measure the outer diameter of the commutator and, if the wear is greater than the limit, replace the rotor. -
Switch Outer Diameter:
- Standard: 28.0-28.1mm
- Limit: 27.5mm
3. Using the indicator, measure the runout of the commutator and, if it is greater than the limit, replace the rotor.
Switch beat:
- Standard: less than 0.02mm
- Limit: 0.05mm
4. Check the switch segments for wear, dirt, and metal particles. If the surfaces of the segments are dirty or burnt, sand them with #500 or #600 sandpaper.
5. Measure the depth of the mica. If the depth is less than the limit, correct with a hacksaw blade.
Depth of mica:
- Standard: 0.4-0.5mm
- Limit: 0.15mm
6. Verify that there is continuity between each switch segment.
7. Place the rotor on the prism, place the hacksaw blade parallel to the core and carefully turn the rotor. If the hacksaw blade is attracted to the core or vibrates, the rotor windings are closed.
8. Check continuity between commutator and shaft, between commutator and core.
9. Using a megger with a standard voltage of 500V, measure the insulation resistance between the commutator and the core.
- Standard resistance: 0.1 MΩ (under voltage above 500V)