When checking windings on a three-phase motor, the resistance readings should:

When checking windings on a three-phase motor, the resistance readings should:

• A. All read the same
• B. Two readings equal, third higher
• C. All read different
• D. One reading is zero

Answer: (A)

Windings in a healthy three-phase motor have equal DC resistance so each phase carries the same current and creates balanced magnetic fields. When you measure resistance with an ohmmeter across each winding, you should see roughly the same value for all three. This equality indicates the windings are intact and uniform. If one winding reads higher, it points to a damaged winding or bad connections; if a winding reads zero or very low, that suggests a short or a severe fault. Wide differences among the three readings mean the winding set isn’t balanced. So the best indicator of a healthy motor winding set is that all three windings read the same (within tolerance).

Windings in a healthy three-phase motor have equal DC resistance so each phase carries the same current and creates balanced magnetic fields. When you measure resistance with an ohmmeter across each winding, you should see roughly the same value for all three. This equality indicates the windings are intact and uniform. If one winding reads higher, it points to a damaged winding or bad connections; if a winding reads zero or very low, that suggests a short or a severe fault. Wide differences among the three readings mean the winding set isn’t balanced. So the best indicator of a healthy motor winding set is that all three windings read the same (within tolerance).