Introduction

Over 15 years in industrial automation, I’ve fixed 200+ false alarm cases. Let’s cut through the guesswork and tackle what really causes Bently 7200 sensors to cry wolf.

1. Oil Contamination – The Silent Killer

Hydraulic leaks coat probe tips, dampening eddy currents. Unlike standard sensors, the 7200’s high-frequency design fails faster when oily. Pro tip: Use IP67-rated cable glands – reduced oil ingress by 90% at a GE plant in 2021.

2. Cable Fatigue: More Than Just Fraying

Vibration cracks inner shielding before outer damage appears. Check impedance values monthly – a drop below 85Ω means replace cables NOW. Cheaper than unplanned downtime.

3. EMI From VFDs – Your Hidden Enemy

Variable-frequency drives emit noise that mimics real faults. Install ferrite cores every 1.5 meters on sensor cables. Bonus: Add grounded metal conduits (saves 70% troubleshooting time).

4. Wrong Thresholds for Aging Machinery

Older machines vibrate more – but most keep factory settings. Recalibrate alarms using 3-month vibration trend data, not specs from new gear. My AB client cut false alerts by 65% this way.

5. Temperature Swings Lie to Sensors

Thermal expansion alters gaps between probe and shaft. If your plant has ±20°C shifts daily, use dual-range calibration (hot/cold states). Works better than “average” settings.

Stop Firefighting – Build a Prevention Plan

• Monthly: Clean probes with non-abrasive EC-200 solvent
• Quarterly: Test cables with megohmmeters (5kV DC minimum)
• Yearly: Full recalibration with Bently Nevada’s ADAPT-2X kit

Get Reliable 7200 Sensor Kits Today

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