At what size do transformers transition from being additive to subtractive?

Transformers transition from additive to subtractive connections based on their size, particularly in terms of their KVA rating. Once transformers reach a certain size, the way they are connected in a circuit changes to optimize efficiency and performance.

In the context of this question, the transition size is typically around 200 KVA. At this rating, transformers start utilising subtractive connections to manage the load and improve voltage stability in the system. Subtractive connections help in balancing the loads more effectively when larger capacity transformers are involved, allowing for better management of electrical power distribution in a network.

Understanding this transition is crucial for linemen, as it impacts how transformers are installed and integrated into power systems, ensuring that they operate efficiently and safely at higher capacities.

The other sizes mentioned, like 100 KVA, 150 KVA, and 250 KVA, represent various points on the spectrum of transformer connections, but it's specifically at 200 KVA that the shift from additive to subtractive connections typically occurs. This distinction is important for selecting the correct configuration and ensuring reliable power delivery in electrical systems.