Shaft Grounding Improves Electric Rail Reliability
Like other electric vehicles, electric trains offer significant benefits over petroleum-powered trains. Electric engines cost around 20% less than diesel engines, and their maintenance costs are 25-35% less. They also produce less noise and far less pollution. Diesel engines produce large amounts of soot, volatile organic compounds, and toxic nitrogen and sulfur oxides. While opinions vary on climate change, most people agree that black grime, acid rain, and smog are things you want less of rather than more.
Like all technologies, though, rail electrification has its challenges. There is the infrastructure problem - electrifying a national rail system is an enormous project, though it can be done. Even with the infrastructure in place, electric trains are still vulnerable to other, sometimes unexpected, problems.
Such as electrical bearing damage. The traction motors in electric trains are controlled by variable frequency drives, which have the unfortunate side effect of generating a voltage between the shaft and frame of the motors they control. This "shaft voltage" can and does discharge through the motor bearings, causing electrical damage and premature failure. Premature failure means premature maintenance, which means more expense for the operator and higher ticket or freight charges for consumers.
Variable frequency drives can also produce electromagnetic interference (EMI), disrupting controls and other electrical systems on the train.
Luckily, both of these problems are soluble. The AEGIS® Shaft Grounding Ring creates a low-resistance electrical path between the motor shaft and frame. Consequently, shaft voltage bleeds harmlessly through the ring instead of arcing through the bearing. At the same time, it guides electrical noise back to the drive instead of leaving it to wander freely and interfere with other systems.
We've done a case study on shaft voltage reduction in electric trains in Halle (Saale), Germany. Before AEGIS was installed, the motors built up 7-8 volts before discharge occurred. Our Shaft Grounding Rings reduced that to under one volt, essentially eliminating discharge through the bearings.
AEGIS Shaft Grounding Rings also have a 2-year extended warranty against bearing fluting damage. No other form of shaft grounding offers a warranty like this.
To learn more about AEGIS shaft grounding and best practices for electrical bearing protection - for motors and generators - sign up for a training. We offer monthly live training webinars, and we can also visit your facility to review your exact application.