65. Peculiarities of Delta Connection in Electrical Power Systems

In the first course in Electrical Engineering, one is taught about the equivalence between star and delta winding and the formula for conversion from star impedance to delta impedance and vice versa. An impression is created that, looking from terminals, performances of star and delta windings are identical. Though this is true for positive (and negative) sequence quantities, the performances of star and delta windings are dramatically different for zero sequence quantities. In this article, Author will illustrate a few examples in which presence of delta winding leads to peculiar phenomena in power systems.