Lead identity
Map each external wire to its intended winding terminal.
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Stator Production Quality
Verify which leads belong together, how each phase is oriented and what the final terminal labels mean before the rotor is installed.
Engineering Overview
Continuity identifies which conductors form a circuit. Relative polarity identifies the orientation of a coil or phase group. Phase sequence describes the order of a three-phase waveform or supply. A resistance meter can help find open leads and unequal branches, but it cannot by itself tell whether a coil group was connected in reverse. A mains phase-rotation indicator checks the supply; it does not prove the internal polarity of an unassembled stator.
Map each external wire to its intended winding terminal.
Check circuit paths against the connection drawing.
Confirm coil start and finish orientation by an approved method.
Validate intended rotation only after the motor and drive are configured.
Image Gallery
These views illustrate winding construction, stator access, a measurement setup and the rotating-field concept; they are not a substitute for a specific motor connection drawing.
First Principle
Label conventions are meaningful only when tied to an approved schematic. For a six-lead, three-phase winding, the design may identify the phase starts and finishes as U1/U2, V1/V2 and W1/W2. A three-lead internally connected stator exposes fewer endpoints, so some internal checks require in-process access before the common point or delta junction is closed.
Do not assume that wire color, slot position or equal ohmic readings establish polarity. Create a traceable map of actual lead IDs, winding groups, connection joints and terminal markings for each revision.
Test Matrix
| Question | Suitable Check | Interpretation | Limit |
|---|---|---|---|
| Which leads share a path? | Continuity or winding-resistance map | Identifies accessible phase and branch circuits | Does not establish polarity |
| Are three phases balanced? | Temperature-corrected resistance; inductance where specified | Flags opens, shorts or connection variation | Equal values can still hide a reversed group |
| Is a coil group reversed? | Approved low-voltage polarity or induced-voltage comparison | Checks relative start/finish orientation | Requires known reference and documented fixture |
| Is insulation intact? | Approved resistance, hipot or surge procedure | Checks a different failure mode | Not a lead-identity test |
| Will the assembled motor rotate as intended? | Controlled low-speed functional test with specified drive | Confirms system wiring and rotation direction | Cannot replace earlier in-process checks |
Production Route
Use the approved slot map and connection revision.
Tag coil starts, finishes and branch junctions before tying.
Record every expected and unexpected path.
Use a validated low-energy method and reference phase.
Apply released terminal labels and inspect joints.
Measure balance, insulation and then system rotation.
Failure Diagnosis
| Finding | Possible Cause | First Response |
|---|---|---|
| Open circuit at one phase | Unjoined lead, damaged wire or incorrect tag | Inspect in-process joints and trace individual groups |
| Resistance imbalance | Connection error, branch mismatch or temperature difference | Normalize conditions and compare the released circuit |
| Polarity result reversed | Start/finish swap or reversed coil group | Stop closure; verify reference and fixture before rework |
| Unexpected continuity between phases | Incorrect bridge or unintended contact | Isolate junctions and inspect the termination area |
| Motor runs opposite direction | Supply or drive phase order mismatch | Compare drive settings and connection drawing; do not assume a stator defect |
Engineering Support
The best checkpoint is usually before the lead joints disappear under lacing, impregnation or potting. A documented fixture can reduce dependence on individual operator memory. Store the tested lead map, instrument setup, applied stimulus, result interpretation and stator serial or batch ID so a later motor-level issue can be traced to the exact assembly state.
Ningbo Vanguard Technologies supports stator winding, motor components, rapid prototyping and production process review. We can help translate a winding diagram into practical in-process checks and inspection records.
FAQ
For engineering and quality teams.
No. Resistance identifies electrical paths and balance. Relative polarity needs a method that responds to orientation, with a known reference.
No. Labels must match the released wiring and drive convention. Rotation depends on the applied phase sequence and the full motor configuration.
A supply phase-rotation tester checks the three-phase source. It does not by itself verify the internal polarity of isolated stator coils.
Preferably while the relevant coil ends remain accessible, before permanent joints, impregnation or encapsulation conceal them.
A controlled motor-level test confirms the drive, sensor and phase connection as a system, including errors introduced after the stator bench test.
Share the winding diagram and terminal requirements for engineering review.
