Tag: Shielding & Grounding

Stop Signal Noise & PLC/DCS Glitches

Clean data is vital in industrial control systems. As an operations manager, I’ve seen signal noise turn reliable data into headaches, causing PLC/DCS glitches. Your Bently Nevada 991 thrust transmitter’s precision can be ruined by electrical interference. This guide shows essential shielding and grounding practices to ensure rock-solid data.

Why Signal Noise Threatens Your Operations

Signal noise isn’t just annoying – it’s dangerous. Erratic signals from your 991 transmitter can cause:

• ⚠️ False alarms and unnecessary shutdowns
• ⚠️ Missed real machinery problems
• ⚠️ Corrupted thrust position data

Key Insight: While the 991 is robust, industrial environments aren’t. Motors, VFDs, and communication lines create interference that proper shielding blocks.

Essential Shielding Practices

1. Use Proper Shielded Cables

• Always use Bently Nevada’s shielded cables
• Never substitute with unshielded alternatives
• The braided shield acts like a Faraday cage against noise

2. Smart Cable Routing

• ↔️ Keep 12+ inches from power cables
• ⤵️ Cross other cables at 90-degree angles
• 🚫 Avoid motors, transformers, and welders

3. Regular Cable Inspections

• Check for nicks, cuts, or crushing
• Test shield continuity monthly
• Replace damaged cables immediately

Mastering Grounding Techniques

The Golden Rule: Single-Point Grounding

• Ground shield at monitoring end ONLY (PLC/DCS cabinet)
• Never ground both ends – creates noise antennas
• Use dedicated instrument ground point

Proper Ground Connections

• 🔧 Clean contact surfaces thoroughly
• 🔩 Use star washers for metal-to-metal contact
• 📏 Check tightness quarterly (vibration loosens connections)

Step-by-Step Installation Guide

1. Mount Transmitter – Secure on clean surface
2. Route Cable – Maintain 12″ from power sources
3. Transmitter Connections – Connect wires (leave shield unconnected)
4. Monitoring End – Connect to PLC/DCS input card
5. Ground Shield – Connect only at rack ground bus
6. Verify – Test shield continuity (grounded at one end only)

Maintenance & Troubleshooting

Critical Benefits

• ✅ Eliminate false alarms and shutdowns
• ✅ Prevent missed machinery failures
• ✅ Ensure accurate thrust position data
• ✅ Extend transmitter lifespan
• ✅ Reduce maintenance costs by up to 40%

Final Recommendation

Proper shielding and grounding aren’t optional – they’re essential for reliable operations. Following these practices ensures your Bently Nevada 991 delivers accurate data, protects turbines, and prevents costly PLC/DCS glitches. The few hours invested in perfecting your setup prevent weeks of troubleshooting.

Get Noise-Free Monitoring – Explore Powergear X Automation’s Bently Nevada Solutions