CRYOGENIC FREEZING & SHAFT REPLACEMENT
SCENARIO
A 200kW, 4-Pole motor used to drive a large fan on our customer’s site had failed due to a possible seizure in its application, resulting in deformation to the shaft and damage to the motor windings. This was a critical motor on site and due to lengthy lead times on replacements, the customer chose to have the motor repaired.
SOLUTION
To begin the repair, the damaged shaft needed to be removed and replaced. This was done following the procedure below:-
- Original, damaged shaft was bored from the rotor and its precise dimensions were noted.
- New shaft was designed and manufactured.
- New shaft submerged into a specially insulated enclosure with liquid nitrogen.
- Once cooled and its diameter sufficiently reduced, the shaft was removed from the enclosure and reinstalled into the rotor assembly.
- The newly installed shaft was then left in the rotor assembly to return to its ambient temperature and re-expand to its original diameter, creating the desired interference fit.
OUTCOME
Following the successful reinstallation of the shaft into the rotor assembly and ensuring that the rotor was correctly re-balanced, the motor was fully rewound, re-insulated, painted to the customer’s specification and delivered back to site to be commissioned.
