What are the maintenance items for high-voltage motors

​I. Pre-Maintenance Preparation​

1. ​Safety Isolation & Power Shutdown​

   • Disconnect and lock out the power supply (LOTO), verify voltage absence using a discharge rod, and ground the motor windings to prevent accidental energization.
   • Post warning signs and establish a restricted zone. Personnel must wear 10kV insulated gloves, boots, and goggles.

2. ​Preliminary Fault Diagnosis​

   • ​Visual Inspection: Check for cracks, burn marks, or excessive dust on the casing and ensure legible nameplate data.
   • ​Electrical Tests: Measure insulation resistance with a megohmmeter (e.g., 2500V for 6kV motors; minimum 1MΩ/kV). Record polarization index (≥2.0) and absorption ratio (≥1.3).
   • ​Mechanical Check: Rotate the rotor manually to detect bearing obstruction or abnormal noise.

​II. Motor Disassembly​

1. ​External Component Removal​

   • Label and disconnect power cables (e.g., U1, V1, W1), then short-circuit and ground them with copper wires.
   • Remove cooling fans, shrouds, and couplings, documenting the disassembly sequence.

2. ​Bearing & End Shield Removal​

   • Mark alignment between end shields and the frame before disassembly. Use pullers or copper mallets to avoid damaging bearings.
   • Inspect bearings for pitting, cracks, or excessive play (e.g., >0.2mm clearance requires replacement).

3. ​Rotor Extraction​

   • For large motors, use balanced hoisting tools to extract the rotor without contacting stator windings. Measure air gap uniformity (deviation ≤±5%).

​III. Core Component Maintenance​

1. ​Stator Inspection​

   • ​Winding Check: Identify grounding, short circuits, or breaks. Re-insulate damaged areas with Class F mica tape (10 layers) or rewind if necessary.
   • ​Core Repair: Tighten loose laminations with insulation wedges; perform core loss tests on overheated sections.
   • ​Slot Wedge Fixing: Secure loose wedges with epoxy resin to eliminate hollow sounds.

2. ​Rotor Maintenance​

   • ​Bar Repair: Weld broken rotor bars (copper/aluminum) using TIG welding or replace with copper bars.
   • ​Slip Ring/Commutator: Machine surfaces to roughness Ra≤1.25μm; adjust brush pressure to 15-25kPa.

3. ​Lubrication & Cooling System​

   • Clean bearing housings and repack with grease (e.g., lithium-based, ≤2/3 capacity). Clear blocked cooling ducts and replace damaged fan blades.

​IV. Reassembly & Testing​

1. ​Reassembly Steps​

   • Reverse the disassembly sequence. Heat bearings to 80–100°C for installation (avoid direct flame exposure).
   • Seal terminal boxes with dual-layer protection (rubber gasket + waterproof putty). Ground cable shields at one end.

2. ​Electrical Tests​

   • ​DC Withstand Test: Apply 2.5× rated voltage (e.g., 25kV for 10kV motors); leakage current deviation ≤50%.
   • ​No-Load Test: Run for 2 hours, monitoring current imbalance (≤5%), bearing temperature rise (≤55K), and vibration (≤2.8mm/s).

3. ​Protection Device Calibration​

   • Verify differential protection response time (≤35ms) and overcurrent tolerance (±5%).

​V. Documentation & Maintenance Planning​

1. ​Data Archiving​
   • Record insulation resistance, withstand voltage, and no-load current for trend analysis.
2. ​Scheduled Maintenance​
   • ​Minor Maintenance (6–12 months)​: Clean, tighten bolts, and replace lubricant.
   • ​Major Overhaul (5+ years)​: Full disassembly and winding replacement.

​Critical Notes​

• ​Safety Compliance: High-voltage tests require a team; keep fire extinguishers ready.
• ​Environmental Control: Maintain humidity ≤80% to prevent insulation damage.

This procedure should be adapted based on motor specifications. For OEM-specific guidance , consult manufacturer manuals.