Shorting the 3-Phase Side of a Breakout
Grounding the 3-Phase Side of a Breakout
With the introduction of single-line diagram (SLD) capabilities in PSCAD, a few special components (i.e. Breakout, 3-Phase Short, and 6 to Twin 3-Phase Splitter) have been included in the Master Library, to help provide a transparent interface between the SLD and the 3-phase view formats.
There are a few configurations that must be avoided when using these components. These are outlined below:
The Breakout component is a mapping device, that is it does not create real electrical nodes on its 3-phase side. Rather it associates these connections with those of the single-line diagram side. Therefore, at no point should any of the 3-phase side connections be shorted. Once a series element (such as a Resistor) is inserted, normal electrical connections are allowed.
NOTE: The illegal connection shown above will result in an error message Short in breakout at '<Node>'. Node array elements must be uniquely defined.
A similar concept is true for the 6 to Twin 3-Phase Splitter, as shown below:
The Breakout component is a mapping device, that is it does not create real electrical nodes on its 3-phase side. Rather it associates these connections with those of the single-line diagram side. Therefore, at no point should any of the 3-phase side connections be grounded. Once a series element (such as a Resistor) is inserted, normal electrical connections are allowed.
NOTE: The illegal connection shown above will result in an error message Invalid breakout connection to ground at '<Node>'. Node array elements cannot be individually grounded.
A similar concept is true for the 6 to Twin 3-Phase Splitter, as shown below:
The Breakout component is a mapping device, that is it does not create real electrical nodes on its 3-phase side. Rather it associates these connections with those of the single-line diagram side. As such, a special condition that cannot be mapped is referred to as an 'unbalanced' condition, where the unbalance refers to electrical nodes, not actual impedance. For example, consider the following diagram:
NOTE: The illegal connection shown above will result in an error message Branch imbalance between breakouts at '<Node>'. Node array elements cannot be shared between signals.
The basic rule to remember here is that all branches on the 3-phase side must include at least one series impedance. These impedances do not have to be equal or balanced however. For example, the diagram below is perfectly valid:
On a final note, back-to-back Breakout connections are in fact valid, as long as no 3-phase side branches contain an impedance. This is particularly useful when connecting orthogonal buses:
