Electric motors are the backbone of practically every industry. From HVAC systems in commercial buildings to manufacturing equipment, they keep operations running smoothly. But what happens when these motors fail? They must be repaired or replaced, while accruing the enormous costs of unplanned downtime. To keep your motors running reliably, protecting them against problems caused by variable frequency drives (VFDs) is crucial.
Understanding the Downsides of VFDs
Variable frequency drives control motor speed, saving energy in applications where motors can be run slower. However, they produce high-frequency electricity that can damage motor components. In particular, they produce a shaft voltage that can discharge through the bearings. This discharge can cause premature motor bearing failure, potentially bringing production to a halt. For facility managers and maintenance professionals, preventing these avoidable problems is a top priority.
The Role of Shaft Grounding Rings
One effective solution to mitigate damage done by VFD-induced stray voltage is the shaft grounding ring. The AEGIS® Shaft Grounding Ring provides a reliable path for stray current, channeling it safely around sensitive motor bearings. By installing these rings, you help your motors reach their natural lifespan without unexpected failures.
Enhancing Protection with Essential Accessories
To enhance motor bearing protection further, consider incorporating supplementary accessories that work in tandem with shaft grounding rings.
Colloidal Silver Shaft Coating CS015
Electrical contact between the shaft and the grounding ring is vital to the ring’s functioning properly. AEGIS® Colloidal Silver Shaft Coating effectively ensures a low-resistance contact. CS015 increases shaft surface conductivity and guards against corrosion that can disrupt the grounding path.
Key Specifications:
- Weight: 15 grams.
- Coverage: Suitable for 20-25 applications on a 3-inch (76mm) shaft diameter.
- Shelf Life: 6 months (contents may separate; stir thoroughly before use).
Before applying, ensure the coating has reached room temperature, and always use personal protective equipment.
AEGIS® Shaft Voltage Tester Digital Oscilloscope
Installing grounding equipment is a step in the right direction, but how do you confirm it's working effectively? The AEGIS® Shaft Voltage Tester Digital Oscilloscope provides the answer. This device allows you to accurately measure shaft voltage levels, ensuring that your shaft grounding ring is working properly.
Key Features:
- Display: 5.6-inch TFT LCD color display with 640 x 480 resolution.
- Multimeter Functions: Measures DC/AC volts, resistance, continuity, and diode capacitance.
- Battery Life: Up to 5 hours with a rechargeable lithium-ion battery.
With dual inputs, this oscilloscope functions as a testing and diagnostic tool. Its user-friendly interface supports multiple languages, making it accessible for diverse teams. Regular testing with this device can help you identify problems before they escalate, saving time and resources in the long run.
AEGIS® High-Frequency Grounding Straps
While shaft grounding rings address voltage on the motor shaft, it's equally important to manage high-frequency current’s flow to ground. AEGIS® High-Frequency Grounding Straps offer an efficient solution. These straps are made of flat-braided, tinned copper and provide a low-impedance path for stray current, to help get it to ground without causing other damage.
Benefits of Using Grounding Straps:
- Effective Bonding: Electrically bonds equipment to prevent stray currents from damaging sensitive components.
- Versatile Installation: Features a circular hole on one end for easy mounting and a ring terminal on the opposite end.
- Compatibility: Available in various sizes to fit different NEMA and IEC frame sizes.
Installing grounding straps creates a continuous path for high-frequency currents to safely reach ground. This additional layer of protection complements the shaft grounding ring and helps prevent rotor ground current between a motor and its coupled equipment.
An Integrated Approach to Motor Protection
Protecting your electric motors from the challenges posed by VFDs doesn't have to be complicated. By using shaft grounding rings in conjunction with accessories like colloidal silver shaft coatings, shaft voltage testers, and high-frequency grounding straps, you enhance your motor protection strategy. This comprehensive approach prevents avoidable problems and keeps your operations running efficiently.
AEGIS rings also come with a 2-year extended warranty against bearing fluting damage. No other form of shaft grounding comes with a warranty like this.
To learn more about AEGIS shaft grounding and best practices for electrical bearing protection, sign up for a training. We offer monthly live training webinars, and we can also visit your facility to review your exact application.
