How many PEI units are there per carriage?

In a typical traction system design, each carriage is equipped with two Power Electronic Interface (PEI) units. This configuration allows for redundancy and ensures that the system can maintain operational capability even if one unit fails. Using two PEI units also helps in distributing the load and managing power more efficiently, leading to improved performance and reliability of the overall traction system.

This design choice aligns with industry standards where redundancy is crucial for safety and operational integrity, particularly in railway applications where consistent performance is necessary. The presence of two units also allows for easier maintenance, as one can be serviced while the other continues to operate.