A node can hold up to 26 phases corresponding to the 'A'..'Z' node name extension. The number of phases is set in the Edit definition dialog. For Models input and outputs can be defined as arrays IN[1..5], IN[1..26], OUT[1..18]. A single-phase may or may not have an extension dependent on if it is connected to other n-phase nodes.
Only three-phase nodes can be transposed all other n-phase nodes will always have a phase sequence starting with 'A' followed by 'B' etc.
An n-phase and an m-phase node directly overlapping each other will be make a connection of the min(n,m) phases starting from 'A'. A single-phase node directly overlapping an n-phase node will connected to phase 'A'. A connection between an n-phase and an m-phase node will hold as many phases as the node that was first clicked.
When you draw a connection between an n-phase node and a single phase node the Connection dialog appears. In this dialog the user has to specify which of the n phases to connect to the single-phase node in the Phase index field. You are also advised to give a color or a label to the connection corresponding to the phase index. In a sequence of connection it is the final one connecting the nodes that determine the phase, and no automatic consistency check is performed by ATPDraw when the node names are made from the ATP menu (Run ATP or Sub-process|Make node names). A connection with phase index '0-@' is a pure single phase connection, while a connection with phase index '1-A' explicitly carries the first phase (A if no transposition) and this will affect the single-phase nodes connected to it.
A connection between a 3-phase node and a single-phase with phase index for instance '2-B' is in version 7 affected by transpositions in the 3-phase circuit. Such type of connection can in many cases replace a the Splitter object found under 'Probes & 3-phase' in the Selection menu. The figure below shows the phase index in a 3-phase system using connections. Note that the Splitter object follows the phase sequence, while the connections with phase index do not.
Figure. Various 3-phase connections
Example: Let's say you need to connect a 3-phase node to phase 4-6 of an n-phase node.This is not as trivial as the case with connection to phase 1-3. Actually, it is not possible unless you break the circuit up in single phase nodes as shown in the figure below, to the right. The case to the left using the Splitter does not work.
Left: Fails Right: Correct