Major rehabilitation of a high-power motor (7000 kW) for a critical boiler feedwater pump system - Planta Centro

• Equipment: Boiler Feedwater Pump "A" Motor, Unit 4.

1. Executive Summary

• Key Impact: Assured operational availability of Unit 4 at Planta Centro through the major overhaul of a 7000 kW motor.
• Engineering Applied: The project included advanced diagnostic protocols, mechanical assessment and dielectric recovery to guarantee the pumping of feedwater to the boiler, a process vital to power generation.

2. Technical Challenge (The Problem)

The availability of one of the country's most important thermal power plants depended on the integrity of this medium-voltage asset:

• Asset Specifications: Hitachi motor, 7000 kW, operating at 6.6 kV and 1185 RPM.
• Criticality: As a unit dedicated to the boiler feedwater pump, any deviation in mechanical or electrical parameters directly compromises the steam and power generation of the unit.
• Diagnostic Need: The equipment required an in-depth assessment to detect incipient faults in the core and validate the mechanical tolerances of the bearings and shaft.

3. Comprehensive Solution (Engineering by SIDELCA)

SIDELCA carried out a comprehensive maintenance protocol (Overhaul) under international standards:

• Diagnostics and Specialized Testing:
• Core Loss Test: Validation of the magnetic efficiency of the stator.
• Surge Comparison: Detection of turn-to-turn winding faults.
• Mechanical Assessment: Rotor run-out measurement and verification of tolerances at bearing seats and shaft.
• Dielectric and Thermal Treatment:
• Steam cleaning of the winding with mild solvents and repair of lashings.
• High-Grade Varnishing: Application of solvent-free Dolph Class H varnish with a red anti-flash varnish finish.
• Controlled baking processes for the polymerization of the insulation.
• Improvements and Protection:
• Supply and installation of 1000 W (220 V) space heaters to prevent moisture condensation during shutdown periods.
• Installation of a new set of bearings to guarantee minimum friction and operational stability.

4. Results and Testing (Guaranteed Success)

The project concluded with the certification of the equipment within nominal parameters:

• Acceptance Testing: No-load operating protocol at reduced voltage to validate mechanical and electrical stability.
• Dielectric Certification: Validation of the stator's insulation resistance and polarization index.
• Schedule Efficiency: Technical execution completed within 15 to 20 working days.

5. Project Technical Data