Vertical hollow shaft motors can fail due to electrical bearing damage. You can prevent this by following shaft grounding best practices.
Motor Shaft Grounding Module - Standard : : Industrial & Scientific
BALDOR JL1303A 1/2HP 3450 56J ODP
Baldor EM2539T-G MOTOR W/SHAFT GROUNDING KIT
AEGIS® Shaft Grounding Installation Guide
WPI Low Voltage High Thrust with “P” Base – TECO-Westinghouse
Super-E motor with Baldor-Reliance shaft grounding brush
HOW TO Wire US Hollow Shaft Motor
Motor Shaft Grounding Module - Standard : : Industrial & Scientific
Vertical Motors
Processes, Free Full-Text
Electrical Bearing Protection Q&A Part 6
Energy $aver - GE Motors - PDF Catalogs, Technical Documentation
Color Insert McGraw-Hill Education - Access Engineering
Shaft Grounding for Vertical Hollow Shaft Motors
Aurora Motors - 46WP1HS500PEE Nema Premium Efficiency Vertical Hollow Shaft Pump Motor 500 HP 460V