- General Support
- Oneline & User Interface
- License Key Issues
- Downloading/Installing Software
- Printing
- Reports
- Equipment Modeling
- DAPPER (Demand Load)
- DAPPER (Load Flow)
- DAPPER (Short Circuit)
- CAPTOR (TCC)
- Arc Flash Evaluation
- Equipment Evaluation
- Cable Ampacity
- A_Fault (ANSI)
- IEC 60909 Fault
- IEC 61363 Fault
- TMS (Transient Motor Starting)
- HI_WAVE (Harmonics)
- Unbalanced/Single Phase
- DC Systems Analysis
- GroundMat
- Cable-3D
- Scenario Manager
- Backup & Import/Export
Modeling High-Leg (Open Delta) Transformer
High-leg delta (also called “red-leg” or “wild-leg” delta) configuration are commonly used in older
three-phase electric power installations in which it supplies both line-to-line and line-to-neutral
services in the same distibution system. Typically, it supplies lighting loads connected phase-to-neutral
and 3-phase motor loads at line-to-line voltage.
One common method to create this type of service is by utilizing two transformers: one set as a
single phase connection and the other is set as a single phase mid-tap.

High-Leg Delta Model:
Voltages for each phase:
Phase A: 120V
Phase B: 208V (High Leg)
Phase C: 120V
(Note: 208V is obtained from 120V * √3 )
PTW Model:
To model the high-leg delta in PTW, two parallel single-phase transformers are connected to a
common bus. One is set as single-phase midtap (XF2-0001) and the other as single-phase (XF2-
0002). The high leg (phase B) is the one set as single-phase. In PTW, the transformers will need to
be connected to a fictitious cable for the parallel connection to be valid.

Once the Unbalanced/Single-phase Load Flow is ran, the voltages for each phase shows the
corresponding line-to-neutral voltages as seen on BUS-0001.
three-phase electric power installations in which it supplies both line-to-line and line-to-neutral
services in the same distibution system. Typically, it supplies lighting loads connected phase-to-neutral
and 3-phase motor loads at line-to-line voltage.
One common method to create this type of service is by utilizing two transformers: one set as a
single phase connection and the other is set as a single phase mid-tap.
High-Leg Delta Model:
Voltages for each phase:
Phase A: 120V
Phase B: 208V (High Leg)
Phase C: 120V
(Note: 208V is obtained from 120V * √3 )
PTW Model:
To model the high-leg delta in PTW, two parallel single-phase transformers are connected to a
common bus. One is set as single-phase midtap (XF2-0001) and the other as single-phase (XF2-
0002). The high leg (phase B) is the one set as single-phase. In PTW, the transformers will need to
be connected to a fictitious cable for the parallel connection to be valid.
Once the Unbalanced/Single-phase Load Flow is ran, the voltages for each phase shows the
corresponding line-to-neutral voltages as seen on BUS-0001.