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Electrical Transformer

This example presents a view inside the transformer core using the magnetic library blocks.

The transformer is rated 50W, 60 Hz, 120V/12V and assumed to have an efficiency of 94%, no-load magnetizing current of 1% and a leakage reactance of 2.3%. Core losses are not modeled and the core material B-H characteristic is assumed to be linear.

All electrical components, including the winding resistances, are presented on the top level of the model and the magnetic components are presented inside the transformer system. Open the Transformer subsystem to see how the rectangular core is modeled.

The turns ratio of 10 is reflected in the scope displaying voltages. The transformer initially operates under no-load conditions. At time t = 0.5s, the rated load is turned on. Because of the winding resistances and flux leakage, the secondary voltage drops from 12 Vrms to 11.3 Vrms and the transformer supplies a full load current of 3.9 A rms on its secondary. The flux and mmf scopes show the operating conditions during no-load and full-load. Compare the leakage flux with the core flux, and observe the primary and secondary-side mmfs.

The core geometry assumed is shown below.

  <--L1--><-----L2----><--L1-->
  -----------------------------   --
 |                            |
 |                            |   L1
 |       |------------|       |   --
 |       |            |       |
 |       |            |       |
 |       |            |       |   L2
 |       |            |       |
 |       |            |       |
 |       |------------|       |   --
 |                            |   L1
 |                            |
  -----------------------------   --

where L1 = 0.75 inches, and L2 = 1.5 inches

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