What does Graded Insulation mean in Medium Power Transformers?

Primary side star connected transformers may have a graded insulation on their neutral point in order to optimize the design of the bushing & winding configuration. Due to the electrical characteristic of the neutral point, the Lightning Impulse withstand voltage levels can be graded compared to the primary phases. Thus, we can choose a lower insulated bushing and can design the winding accordingly. This will optimize the overall transformer design. However, this point needs to be agreed with the customer in any case.

Released for: Schneider Electric Canada