EARTHRINGS® Shaft-Grounding Protection for VSD-Driven HVAC&R Motors

Sixth Element Australia supplies EARTHRINGS®, a precision-engineered shaft-grounding solution designed to protect electric motor bearings from destructive electrical discharge caused by VSD/VFD (IGBT-PWM) drives. EARTHRINGS® provide a continuous low-impedance grounding path that prevents bearing fluting, EDM pitting and vibration-related failures in HVAC-R plant.

Modern HVAC&R systems—AHUs, cooling towers, CHW/CW pumps, large FCUs, industrial fans, VRF/VRV equipment—rely heavily on VSDs. However, VSDs introduce shaft voltage, a well-established cause of premature bearing failure and unplanned plant outages. EARTHRINGS® directly address this reliability risk.

The Engineering Problem: VSD-Induced Shaft Voltage

VSD drives using IGBT PWM switching generate:

• Common-mode voltage
• High-frequency switching spikes
• Rotor charge accumulation

When unmanaged, this discharges through motor bearings, potentially causing:

• EDM pitting
• Fluting patterns on raceways
• Lubrication carbonisation
• Accelerated wear and vibration
• Sudden motor failure

This affects cooling tower fans, AHU supply/return fans, chilled-water pumps, condenser-water pumps, and industrial ventilation motors.

 Independent Media Coverage (HVAC&R News, ProcessOnline + Industry Context)

HVAC&R News (AIRAH) – Technical Feature

https://hvacrnews.com.au/business/sixth-element-australia-offers-arc-earthrings/
AIRAH’s HVAC&R News covered EARTHRINGS® as a reliability solution for VSD-driven motors, explaining how shaft voltage forms in PWM-driven systems and how grounding rings mitigate bearing damage.The article emphasises the relevance to HVAC fans, pumps and cooling towers, noting the wide shaft-size range and suitability for both LV and HV motors.
This positions EARTHRINGS® as an HVAC-R specific reliability technology backed by Australia’s peak HVAC engineering body.

ProcessOnline – Industrial Automation Spotlight

https://www.processonline.com.au/content/equipment/product/arc-earthring-shaft-grounding-rings-612225279
ProcessOnline showcased EARTHRINGS® within industrial automation applications, highlighting their adjustable ARC™ design, wide size range and suitability for environments involving dust, moisture, grease and vibration.
This gives EARTHRINGS® credibility across both HVAC and industrial drive systems.

How EARTHRINGS® Work

EARTHRINGS® create a low-impedance path from the motor shaft to the motor frame, safely redirecting electrical discharge away from bearings.

• Technical Features
• Gold-plated conductive micro-fibres

• ARC™ adjustable ring design for alignment and fit
• Solid or split rings for fast retrofit
• Durable in dust, humidity, grease and harsh plantrooms
• Suitable for high-frequency PWM environments

Technical Overview:
https://sixthelementaustralia.com/earthrings/

Where EARTHRINGS® Are Recommended in HVAC-R ( VSD applications only)

• Cooling tower fans
• AHU / MAU supply & return fans
• Chilled-water pumps
• Condenser-water pumps
• Large FCU motors
• Industrial process fans
• Any VSD/VFD-driven motor
• Retrofit scenarios with recurring bearing failures

This ensures correct specification and avoids unnecessary installation.

Why HVAC Contractors, Facilities Managers  and Consultants Consider EARTHRINGS®

Mechanical Contractors

• Prevents premature motor failure
• Reduces warranty costs & call-backs
• Easy retrofit during upgrades
• Ideal for cooling tower reliability
• Works seamlessly with existing VSDs

Consulting Engineers

• Enhances reliability of NCC-compliant VSD systems
• Reduces lifecycle risk in critical buildings
• Provides a validated protection method for PWM-driven motors
• Simple to specify for all major HVAC plant

Facilities Managers

• Reduces outages and emergency failures
• Minimises bearing replacement costs
• Improves uptime of fans, pumps & towers
• Critical for hospitals, data centres & premium assets