Circuits and switching groups

Transformatorenwerk Breimer-Roth GmbH characterizes its three-phase transformers – three-phase transformers – as follows, in accordance with the approach that is used worldwide and is easier for the user to understand:

The 1. capital letter describes the primary input winding and the 2nd lower case letter the secondary output winding.

If no other order information with a more precise assignment of the position of the upper and lower clamping is formulated, the above-mentioned type of labeling is selected! Three-phase transformers are preferably manufactured in Dyn5 if no specifications are available.

Load capacity of the neutral conductor (star point)
In the star-star circuit (Yy), the star point may only be loaded with the full rated current if the neutral conductor of the supplying network is connected to the primary-side transformer star point. If this is not the case, the neutral point can only be loaded with approx. 10% of the phase conductor current.

The same rule applies to three-phase autotransformers that are designed as star autotransformers (YNa0). If a fully loadable star point is required, but this is not available on the mains side, the double zigzag connection (ZZan0) must be selected.