Custom Split Shaft Grounding Ring for a Brazilian DC Motor: Addressing Bearing Electrical Erosion

Customer Background

A customer in Brazil operates a high-power DC motor for a rubber extrusion system. The motor is air-cooled and rated at over 300 HP, with a voltage of 500 VDC and a speed of 1,800 rpm. The motor shaft diameter is 82.5 mm, with a 100.4 mm mounting diameter.

During operation, the customer noticed a persistent current leakage problem in the motor bearing. The bearing showed visible electrical erosion, raising concerns about bearing life and long-term motor reliability.

The Problem: Bearing Damage Continued After Replacement

The customer initially replaced the damaged bearing with a completely new one. However, the electrical erosion problem remained.

This indicated that the bearing itself was not the root cause. If shaft current continues to pass through the bearing, a new bearing can eventually suffer the same type of electrical damage.

The customer therefore needed a way to provide a controlled, low-resistance path for shaft current and keep harmful current away from the bearings.

A Proven Solution, but a New Requirement

Before contacting Volsun, the customer had tested a split shaft grounding ring from Aegis. The trial was successful, and the grounding ring effectively addressed the bearing current problem.

However, the customer was looking for an alternative supplier with better cost efficiency and more stable delivery while maintaining the required electrical protection performance.

This created a clear requirement: develop a customized split shaft grounding ring that could fit the existing motor and provide a practical alternative to the current solution.

Volsun's Custom Split Shaft Grounding Ring

After reviewing the customer's motor specifications and installation conditions, the Volsun engineering team designed a custom two-piece shaft grounding ring, the installation type is press-fit.

Instead of using a conventional one-piece circular ring, the grounding ring was redesigned into two semi-circular sections. This split structure makes it easier to position the ring around the existing motor shaft and better suits the customer's installation requirements.

The customized design was developed specifically around the customer's motor rather than simply selecting a standard grounding ring. By considering both the electrical problem and the mechanical dimensions, Volsun developed a grounding ring solution designed specifically for this application.

Sample in Production

The customized sample drawing has been reviewed and confirmed with the customer. The sample is currently in production and will be prepared for the next stage of testing.

For this Brazilian customer’s application, the goal is not only to provide a reliable low-resistance path for shaft current, helping prevent harmful electrical current from passing through the motor bearings, but also a solution that offers competitive pricing, stable delivery and customized installation compatibility.

A Flexible Alternative for Motor Bearing Protection

This project demonstrates how shaft grounding solutions may need to be adapted to the actual motor rather than relying solely on standard designs.

For large DC motors, industrial motors and other rotating equipment experiencing bearing current or electrical erosion, Volsun can develop customized shaft grounding rings based on shaft diameter, mounting dimensions, motor structure and installation conditions.

Looking for a custom shaft grounding ring for your motor? Contact Volsun to discuss your application and grounding requirements.