Two Winding Transformer - Connection Information

Figure 1: Connection Information (ANSI)

Figure 2: Connection Information (IEC)

Figure 3: Connection Information (Single-Phase)

Option Descriptions
Option Description

ID Name

Uniquely identifies the equipment item. The program automatically assigns a name, but you can change it, if needed. The name can be up to 16 characters long.

For two winding transformers, the program automatically assigns the names TX-1, TX-2, TX-3, and so on.

From Bus

The bus from which the transformer connects, which must already exist on the one-line. Ensure that the From Bus has approximately the same base kV as the transformer's From Rated kV. For reference, the From Bus base kV is displayed next to the bus name.

The base kV displays the highest voltage between the current carrying conductors. For 3-phase or line-to-line connected single-phase equipment, the base kV is the line-to-line (LL) voltage. For line-to-neutral (LN) connected single-phase equipment, the base kV is the line-to-neutral voltage.

To Bus

The bus to which the transformer connects, which must already exist on the one-line. Ensure that the To Bus has approximately the same base kV as the transformer's To Rated kV. For your reference, the From Bus base kV is displayed next to the bus name.

The base kV displays the highest voltage between the current carrying conductors. For 3-phase or line-to-line connected single-phase equipment, the base kV is the line-to-line (LL) voltage. For line-to-neutral (LN) connected single-phase equipment, the base kV is the line-to-neutral voltage.

Phase

The phase type for this item:

  • 3PH: 3 phase
  • 1PH: 1 phase

Conn

The transformer winding connection type, which is either:

  • D: Delta
  • Y: Wye ungrounded
  • YG: Wye grounded (ANSI) 
  • YN: Wye neutral (IEC) 

If YG or YN is selected, grounding impedances can be entered on the Impedance tab under Grounding.

The default settings are D-YG for ANSI, and D-YN with a phase shift of 11 for IEC.

These options are not available for single-phase connections.

Center tap connection

For single-phase, select this check box to indicate that the center tap (neutral) is used.

When this option is selected, the secondary side has a distribution system or service type of 1PH-3W. (See 1PH-3W Systems for more information.) The bus or panel connected to the secondary side must also be a 1PH-3W service.

Note: In load calculations, loads on L1 and L2 conductors are done separately below the secondary side of a 1PH center-tapped transformer. On the primary side, since it is a 1PH-2W system, the load is summed based on kVA.

Lock Auto-Sizing

 When this check box is selected, this item cannot be automatically sized using SmartDesign™ (the auto-design feature).

Phase Shift: Ref: HV Side

For IEC transformers, you can specify the phase shift as related to the notations on a clock. Select from 1, 3, 5, 7, 9, or 11. The high voltage side is used as the reference side.

This option is available only if the Standard on the transformer is set to IEC and the short circuit calculation method in System options is set to IEC-60909.

(Information Icon)

The blue information icon indicates that the item must be disconnected to change the value. See Information Icon for more information.

More Information