SOP: GROUNDING & PROTECTION | FRANCIS UNIT 1
SOP-ELEC-007 REV 2.1

SHAFT GROUNDING & PROTECTION

THE INVISIBLE DESTROYER

SILENT BEARING KILLER

Magnetic imbalances induce voltage on the rotating shaft. Without proper grounding, this voltage arcs through the bearing oil film, vaporizing Babbitt metal and creating thousands of microscopic craters (Pitting).

WHY IT'S SILENT

Unlike mechanical wear, electrical pitting produces no heat or noise until catastrophic failure occurs.

ECONOMIC IMPACT

A 10-year bearing can fail in 18 months if shaft grounding is non-functional.

GROUNDING BRUSH INSPECTION

BRUSH WEAR LIMITS

New Brush Length 40-50mm
Service Limit 15-20mm
REPLACE IMMEDIATELY < 10mm

SLIP SURFACE CLEANING

  • Wipe with Isopropyl Alcohol
  • Gently polish with fine Scotch-Brite (600-grit)
  • Final wipe to bright metal finish
CONTAMINANTS: Silt, Oil Mist, Oxidation.

VOLTAGE MEASUREMENT PROTOCOL

SHAFT-TO-GROUND TARGETS
EXCELLENT < 0.2V
WARNING 0.5 - 1.0V
CRITICAL > 1.0V

Measurement must be taken during unit operation. Use True RMS Multimeter on AC+DC scale.

BEARING PITTING SIGNATURE

  • Surface appears "frosted" or "etched"
  • High Copper/Lead content in Oil DGA
  • Random crater distribution visible under magnification