Simo motors successfully solved the stator winding grounding fault of a chemical plant's 6kV high-voltage motor.

I. Fault Background: Sudden shutdown, critical production situation

Customer Information:

• Client OrganizationA major chemical company (name withheld at client's request)
• Equipment Type6kV High-Voltage Asynchronous Motor
• Key ParametersRated power: 710 kW Rated voltage: 6 kV Rated current: 82 A Rotational speed: 2985 r/min
• application scenarioDrive critical process pumps
• Fault Symptoms：
  • Sudden trip during operation; relay protection indicates "stator ground fault."
  • On-site testing revealed that the insulation resistance of all three-phase windings to ground had dropped to zero.
  • Equipment emergency shutdown severely disrupted production processes.

II. In-Depth Diagnosis: Identifying the Root Cause of the Malfunction

Simo motorsUpon receiving the client's urgent request, the technical team arrived on-site within two hours to conduct a systematic diagnosis:

1. Preliminary Testing and Data Analysis

• Using a megohmmeter to measure the winding-to-ground insulation resistance, the reading is below 0.5 MΩ (Standard requirement: not less than 1 MΩ under hot conditions).
• DC resistance testing indicates balanced resistance across all three phases, ruling out winding open circuits and turn-to-turn short circuits.
• Preliminary determination indicates a breakdown of the stator winding's primary insulation to ground.

2. Precision Positioning and Root Cause Analysis

• Scanning the open-circuit point of windings using the open-winding transformer method
• Precise fault location using pulse wave reflection method
• Fault LocationA winding insulation breakdown point was detected 15 cm from the end of the core.
• root cause：
  1. Long-term operation in humid environments causes moisture ingress and aging of the winding insulation.
  2. Insulation materials naturally age, resulting in a decrease in electrical strength.
  3. Recent power grid operational overvoltage surges have become the primary cause of breakdowns.

III. Specialized maintenance programme and implementation process

Based on the diagnostic results, we have developed a detailed repair plan:

1. Faulty Winding Repair and Handling

• Detailed TeardownCarefully remove the faulty winding using specialized tools, taking care not to damage the iron core.
• Insulation treatmentThoroughly clean the groove and remove burrs by sanding with three grades of sandpaper.
• Application of New Materials：Selecting Simate's specially formulated H-class insulation material to enhance heat resistance rating

2. Implementation of Professional Insulation Processes

• Vacuum Pressure Impregnation (VPI): Immersion treatment is performed in specialized equipment to ensure thorough penetration of the insulating varnish.
• High-temperature curingStrictly follow the process curve for temperature ramping and curing to ensure insulation performance.
• Anti-aliasingApply specialized anti-corona varnish to the winding ends to improve the electric field distribution.

3. Comprehensive Testing and Validation
After completing the repairs, we conducted rigorous testing and verification:

• Insulation Resistance TestWinding insulation resistance to ground restored to over 1000 MΩ.
• DC Withstand Voltage TestPassed DC withstand voltage test at 2.5 times rated voltage
• AC Withstand Voltage TestPasses standard power frequency AC withstand voltage test
• No-Load TestNo-load current balance, vibration, temperature rise, and other parameters all meet standards.

IV. Maintenance results and customer value

1. Direct repair results

• The equipment passed its initial test run after being repaired.
• All electrical parameters exceed factory standards.
• It has been operating stably for 8 months without any issues.

2. Value Created for Customers

• Avoid major lossesQuick response minimized production downtime losses for the customer by approximately 1.2 million yuan.
• Performance EnhancementMotor efficiency improved by 21% (TP3T), with an estimated annual electricity savings of approximately 50,000 kWh.
• Life ExtensionAfter maintenance, the equipment's expected service life is extended by more than 10 years.
• Management OptimizationAssist clients in establishing equipment preventive maintenance systems

V. Case Summary and Professional Recommendations

1. Technical Summary

• Accurate fault diagnosis is the key to successful repairs.
• Advanced VPI process ensures insulation treatment quality
• Rigorous testing standards ensure repair reliability.

2. Preventive Maintenance Recommendations
Based on the experience gained from this case, we recommendHigh voltage motorsUser:

• Regular inspection：
  • Measure insulation resistance monthly and establish trend analysis.
  • Conduct DC leakage current testing every six months.
  • Comprehensive preventive trials are conducted annually.
• Operation and Maintenance：
  • Keep the motor operating environment dry and clean.
  • Monitor bearing temperature and vibration conditions
  • Record operational data and establish equipment health records.
• Professional Assurance：
  • Select a repair service provider with professional qualifications.
  • Establish an emergency repair plan
  • Perform regular professional maintenance

VI. Professional Advantages of Xima Motors

This case study demonstrates Xima Electric's core strengths in the field of high-voltage motor maintenance:

1. rapid responseOn-site within 2 hours, diagnosis completed within 24 hours
2. Professional TeamTechnical experts with over 20 years of experience
3. Advanced Processes：Possesses complete VPI equipment and processes
4. Quality AssuranceProvides a 12-month warranty period