Using a third rail is a good way to reduce the wear and tear that comes from operating train engines. However, it isn't a cost-free solution. Given the potential system-wide implications, you need to pay close attention to the following signs that third rail train equipment may be failing.
Brief Power Losses
Trains stay in contact with the third rail to maintain power. Contact is rarely perfect, but it should always be sufficient to keep the vehicle moving on schedule. As some components fail, there may be brief power losses. Notably, the affected section might be short enough that the train's momentum allows it to coast to another electrified segment. In other words, the train will lose power briefly and then regain it.
You might notice that the power losses don't happen in predictable spots, though. In that scenario, you could be dealing with a failing power supply.
Similarly, the collector shoe could also be failing. It might wear down to the point that it's fine in most spots but loses contact in locations that aren't ideal. For example, a curve or slope might lessen contact enough to cause a momentary power loss.
Over time, the rails may also become damaged. Some of this is expected wear and tear. However, it can get to the point that it makes the train's motion jerky. This also may happen if the collector shoe is failing. The jerking motion may arise from inconsistent contact.
Sparks and Arcs
Modern third rails shouldn't throw sparks. Likewise, the electricity shouldn't visibly arc between the rail and the collector. If you see these problems, there is likely some form of damage or contamination on the rail or the shoe. Electrical systems are also possible. If you've performed maintenance and not found the problem, you may need to contact a third rail train equipment manufacturer to discuss potential problems with electric delivery subsystems.
Excessive electrical resistance can cause the rail or shoe to scorch. This happens due to contamination. It also occurs as third rail train equipment wears down. If you can see discoloration of the rail or shoe, you should contact a manufacturer to order replacement parts.
Third rail systems have built-in monitors. Sensors in the train or along the track may detect problems and trigger alarms. If alarms trigger regularly at certain locations or during particular conditions, there may be an equipment issue.
Reach out to a third rail train equipment manufacturer to learn more.