Electrical power is a field of continuous improvement, with ever-evolving control methods. Since the development of the first electric motor, various devices and techniques have emerged to enhance reliability and efficiency.
For example, it has been proven that shaft grounding is essential to optimize an electric motor’s performance, especially in industrial settings.
In this article, our electric motor specialists explain why shaft grounding is necessary and how to ensure effective implementation.
Why Is Shaft Grounding Important?
Shaft grounding prevents bearing damage by protecting them from circulating currents and minimizing voltage buildup on the motor shaft. This buildup can eventually discharge through the bearings or other sensitive motor components, causing damage.
Excessive shaft voltage can originate from several sources, including:
- Electrical induction;
- Electromagnetic leakage;
- High-frequency circulating currents generated by variable frequency drives (VFDs).
Electric motors, particularly those paired with VFDs, can act as electromagnetic dynamos, with rapidly moving components generating unwanted voltage. This excess voltage accumulates mainly on the motor shaft. When this buildup surpasses the insulating capacity of the lubricant, it discharges through the motor bearings or connected equipment bearings.
This phenomenon should not be overlooked. Even though the motor shaft is designed to endure high stress, other more sensitive components, such as certain bearing types, are at risk and require protection.
Regardless of the source, excessive shaft voltage can be effectively minimized using a high-quality shaft grounding device that redirects the current safely to the ground.
Plan Your Motor Shaft Grounding Today
Shaft Grounding Devices: Effective Protection for Bearings
Without a shaft grounding device, motor bearings typically provide the path of least resistance for stray currents accumulated on the motor shaft.
When these currents pass through the bearings, electrical arcs occur, damaging the bearing surfaces. This leads to noise, vibration, and ultimately premature bearing failure.
It is crucial to redirect stray shaft currents away from the motor to protect the bearings and other internal components from harmful electrical currents.
Shaft grounding devices achieve this by safely channeling electrical currents from the motor shaft to the ground. These devices may include grounding rings (Grounding Brushes) or other specialized equipment detailed below.
Identifying Shaft Grounding Issues in Electric Motors
If the bearings of a motor (or coupled equipment) wear out abnormally fast, one of the most likely causes is the absence of proper shaft voltage grounding. This can be confirmed by inspecting the bearings for the following signs:
- Fluting;
- Fusion craters;
- Frosting;
- Pitting;
- Surface discoloration.
Shaft Grounding Devices Protect More Than Just Bearings
As motor designs increasingly incorporate computer systems and integrated circuits, shaft grounding devices provide more than just mechanical wear prevention.
In fact, advanced circuits should be properly shielded from increased and fluctuating electrical residues to ensure the consistent performance of motors relying on sensitive electronic components.
Shaft Grounding Installation and Maintenance Should Be Left to Professionals
The installation of shaft grounding equipment should always follow established safety standards. Additionally, ensuring all components are correctly sized and positioned during installation is crucial.
Regular maintenance is equally important to ensure the grounding system remains effective and safe over time.
Helwig Carbon Bearing Protection Kits
Helwig Carbon bearing protection kits utilize proven silver graphite brush technology to ground motor shafts effectively. These kits safely divert induced electrical currents away from the bearings, protecting them from damage and failure.
They have consistently demonstrated their effectiveness in protecting bearings in various types of equipment powered by electric motors:
- Industrial pumps;
- Fans;
- Compressors;
- Elevators;
- Conveyors;
- Mining equipment;
- HVAC systems;
- And more.
Interestingly, the resistance of Helwig Carbon’s silver graphite is over five times lower than that of carbon fiber, significantly reducing the risk of stray currents passing through the bearings.
But this isn’t the only advantage of Helwig Carbon bearing protection kits. Additional benefits include:
- Typically reducing shaft voltage to below 1V at frequencies above 1MHz;
- Lasting 10 years or more under normal conditions;
- Providing the path of least resistance to the ground;
- Adapting to most electric motor designs and shaft sizes;
- Requiring minimal maintenance;
- Featuring internal mounting components that are shielded from external contaminants.
Omnifab Helps Extend the Life of Your Electric Motors
In summary, it’s important to remember that unwanted current can accumulate inside a motor, particularly on its shaft, if not properly grounded. To efficiently dissipate this current and prevent damage to bearings or other delicate motor components, a well-maintained shaft grounding device is essential.
For installation or maintenance of your shaft grounding devices, always trust experienced electric motor repair specialists like Omnifab.
Contact us today to learn more about this specialized expertise from Omnifab!
