The main switch transformer of ATX power supply

The main switch transformer in Figure 1 comes from a "single-pole switching power supply with a single-tube forward topology. Its model number is EI-33A, 33 of which indicates that its core length is 33mm. Since the transformer is often included in its model number the length of the core in millimeters is visible. It can be seen that the length data of the transformer should be used to measure the performance of a transformer as a whole.

Figure 1

This is actually very easy to understand. To understand this problem, the reconciliation is based on the nature of the function (energy conversion) of the transformer. If the length of the core is large (the total volume is related to the length), it means that a larger core can accommodate more magnetic energy during the "electromagnetic" process. In another expression, as the core increases, the ability to convert more energy into magnetic field energy through the transformer and continue to deliver energy to the transformer in the subsequent stage is improved in a single oscillation cycle. The final result is that the output power of the entire power supply can be increased by outputting more power (current) at the output terminal of the ATX power supply.

This is the fundamental reason for judging the true output power of a specific ATX power supply by observing the external dimensions of the main transformer. Unexpectedly, a power supply with a nominal output of 450W uses a main transformer with a length of 33mm, which is the most common false-defense means of the cottage power supply.

This article is from Allicdata Electronics.