# Three-Phase Transformer 12 Terminals

Implement three single-phase, two-winding transformers where all terminals are accessible

## Library

Simscape / Electrical / Specialized Power Systems / Fundamental Blocks / Elements

## Description

The Three-Phase Transformer 12 Terminals block implements three single-phase, two-winding linear transformers where all the 12 winding connectors are accessible. The block can be used in place of the Three-Phase Transformer (Two Windings) block to implement a three-phase transformer when primary and secondary are not necessarily connected in Y or Delta.

## Parameters

[Three-phase rated power Frequency]

The total nominal power of the three phases, in volt-amperes (VA), and the nominal frequency, in hertz (Hz). Default is `[ 10e6 60 ]`.

Winding 1: [phase voltage R X]

The nominal voltage of the three primary windings (labeled 1) in volts RMS (Vrms), the winding resistances, in pu, and the winding leakage reactances, in pu. Default is ```[ 10e3 0.002 0.05 ]```.

Winding 2: [phase voltage R X]

The nominal voltage of the three secondary windings (labeled 2) in volts RMS (Vrms), the winding resistances, in pu, and the winding leakage reactances, in pu. Default is ```[ 25e3 0.002 0.05]```.

Magnetizing branch: [Rm Xm]

The resistance and reactance simulating the core active and reactive losses, both in pu. For example, to specify 0.2% of active and reactive core losses, at nominal voltage, use Rm = 500 pu and Lm = 500 pu. Lm can be set to `inf` (no reactive core losses), but Rm must have a finite value. Default is `[ 200 200 ]`.

### Note

Refer to the Linear Transformer for explanations on the per unit system.

## Examples

See `power_3phPWM` for an example of use of the Three-Phase Transformer 12 Terminals block in a three-phase double-bridge voltage-sourced converter.