Transformers with power ratings over what value typically have four secondary bushings?

Transformers that have power ratings exceeding 100 KVA generally feature four secondary bushings. This design allows for better load balancing and flexibility in connection configurations for multi-phase or dual-voltage applications. Transformers with higher power ratings are engineered to accommodate increased current flow, which may necessitate additional connections for managing the electrical load effectively.

When the power rating hits 100 KVA and exceeds it, the requirements for insulation and physical space also increase. This often results in the incorporation of four secondary bushings instead of fewer, as it provides more versatility in how the transformer can be connected to the electrical system. This is particularly important in larger systems where load distribution is crucial for operational efficiency and safety.

Lesser-rated transformers (like 50 KVA and 75 KVA) typically manage their power needs with fewer bushings, as the electrical demands and complexities are lower. Similarly, the 150 KVA rating continues to adhere to this norm, but it’s the 100 KVA threshold that marks the general transition where four bushings become standard practice.