Model Monday: Winding Phasing and Orientation

Model Monday: Winding Phasing and Orientation

This is the second part of a two-part Model Monday post series about RSCAD’s three phase, two winding transformer model. Check out last week’s post for the first in the series.

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For a three phase two winding transformer, using the pol1 and pol2 parameters it is possible to specify the winding orientation (ie. The information normally indicated using the dot convention) as shown in the following Figure. For example, specifying pol1= +ve and pol2= +ve means that the node voltage across the transformer for a Y−Y configuration is in phase. Changing pol2 to –ve introduces a 180 degree phase shift.

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It is also possible to specify a phase rotation between primary and secondary. For example, setting both the rot1 parameter and the rot2 parameter to ABC indicates that coupled winding set 1 is connected to A phase on the primary and A phase on the secondary. By setting the rot2 parameter to BCA results in winding 1 on the secondary to be connected to B phase, winding 2 to C phase and winding 3 to A phase. The result is that a 120 phase lead is introduced on the secondary node voltages relative to the primary node voltages. By using the winding arrangement, phase rotation and winding polarity parameters phase shifts as shown in the following table may be obtained.

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