How a mining company reduced costs by over 60% with independent advice

A copper-and-gold operation in Queensland faced a worn Toshiba mill motor and an initial plan for a full stator rewind. An independent review focused the work on what the machine actually needed. The result: the motor returned to service faster and at over 60% lower cost.

Key Results

• >60% cost reduction versus a full rewind.
• Shorter outage with a targeted repair.
• Evidence-based decision backed by standard tests and documentation.

Before vs After

• Before (initial recommendation): Full stator rewind due to missing wedges (~10%) and damaged end-winding grading coat.
• After (final scope): Targeted partial re-wedge of affected slots and application of a new grading coat; coils and core left in place based on test evidence.
• Outcome: Faster return to service with a controlled risk profile and documented test results.

3-Step Timeline

1. Receive & Inspect (Day 0–2): Dismantle, opening report, plan tests.
2. Decide & Execute (Week 1): Partial re-wedge; clean and re-apply conductive grading coat.
3. Verify & Return (Week 2): Acceptance checks, documentation, shipment, and support during re-installation

What We Did

We applied standard rotating-machine assessments to confirm the health of the stator core and windings before committing to scope:

• Wedge tightness survey to locate and quantify loose wedges and plan a focused re-wedge.
• Low-flux core test to check for inter-laminar faults in the stator core laminations.
• Optional electrical checks (partial-discharge trend/spot checks) to corroborate winding condition.

Why This Approach Works

Loose wedges allow bar movement and insulation wear; restoring wedge tightness re-establishes mechanical restraint. A fresh grading coat reduces surface electrical stress at the end-windings. When wedge surveys and core tests are satisfactory, a full rewind is not automatically required.

Our Solutions

• Iris Power Stator Wedge Analyzer (SWA)— assesses and trends stator wedge tightness for planning and post-repair proof.
• EL CID™ Evolution— low-flux stator core testing to confirm lamination integrity.
• TGA-B/TGA-S— portable partial-discharge instruments for motors and generators.
• GuardII+— continuous online condition monitoring with fleet-level data collection and trending via Iris Application Manager.

Results

• Cost: Over 60% reduction versus a full rewind.
• Time: Shorter outage from a limited, clearly defined scope.
• Confidence: Test reports archived to support future maintenance planning.

When a Full Rewind Is Appropriate

• Low-flux core testing indicates inter-laminar faults that require core repairs beyond a limited scope.
• Wedge survey shows widespread looseness or instability across the stator.
• Electrical testing indicates severe winding degradation inconsistent with continued service.