Above NEMA electric motor internal “air baffles” are critical to motor operation & reliability.Megan Thompson
Background: A specific OEM electric motor design use an internal air baffle tied to the inside diameter of the stator coil extensions for two important reason;
- Provide bracing and support to mitigate stator coil movement
- Provide an air draw in coordination with the rotor’s internal cooling fans (See Picture #1) to ensure the proper amount of air circulation for motor ventilation/ cooling.
Picture #1 – View of the Rotor and its two Internal Cooling Fans
The Challenge: IPS received a refinery motor without its internal air baffle. The motor was previously rewound by an unknowing motor repair shop without the internal baffle, resulting in stator coil movement and signs of overheating (See Picture #2).
An experienced IPS winder quickly noticed the missing baffle common to the Specific OEM’s design, and brought it to the attention of IPS Engineering. Without the missing baffle, the coil movement and overheating problems would not have been resolved.
Picture # 2 – Stator coil movement from lack of bracing
The Solution: Before motor disassembly, IPS technicians measured, mapped and recorded the air flow at the motor’s air exhaust. IPS installed an air baffle making sure to measure and record the exact location on the winding data sheet, and the inside diameter of the internal baffle. (See Picture #3) After the stator completed VPI, technicians used a two-part epoxy to fill the gaps between adjacent stator coils and the internal baffle to create an “Air Dam” (See Picture #4), so that the rotor cooling fans will be able to create enough air draw across the inside diameter or newly installed Air Dam, or internal baffle. During the final test run, IPS measures and records the air flow values as we did prior to disassembly.
Picture #3 – Air Baffle is placed with proper alignment and air-gap with the rotor cooling fans
Picture # 4 – Connection End View of the Air Baffle
The Conclusion: Rewinding an Above NEMA motor without its “Air Baffle” can result in a hot running motor and stator coil movement.