What is the most common connection type on the BES?

The most common connection type on the Bulk Electric System (BES) is the Wye-Wye connection. This configuration is frequently used because it provides several advantages in terms of system stability and performance. In a Wye configuration, the neutral points of the windings are connected, which helps in balancing the load across the three phases. This balanced load is crucial for minimizing the risk of voltage imbalances that can affect system reliability.

Additionally, Wye connections are beneficial for connecting to grounded systems, which is essential for safety and to facilitate overvoltage protection. The grounding capability of the Wye connection also helps in reducing the stress on the insulation of equipment and can be advantageous during fault conditions, allowing protective devices to detect and isolate faults more effectively.

While other connection types, such as Delta-Delta, Wye-Delta, and Delta-Wye, are also used in transmission systems for various applications, the Wye-Wye configuration stands out as the most prevalent due to these operational and safety benefits, especially in high voltage applications found in the BES.