An EI-type transformer operates on the fundamental principle of electromagnetic induction, identical to all transformers. It utilizes a core constructed from stamped E-shaped and I-shaped laminated steel sheets stacked together. When alternating current flows through the primary winding wound around the center limb of the 'E', it creates an alternating magnetic field. This magnetic flux circulates through the closed magnetic path provided by the assembled E and I laminations, inducing a voltage in the secondary winding. The turn ratio between the windings determines whether the voltage is stepped up or down.
Product Features
1. Cost-Effective Manufacturing: The simple, rectangular shape of the E and I laminations makes them easy and cheap to mass-produce by stamping, leading to a very economical transformer design.
2. Moderate Performance: It offers a good balance for general-purpose applications. Its magnetic path is less ideal than a toroidal core, resulting in higher magnetic leakage and audible hum, but it is entirely sufficient for many non-critical uses.
3. Mechanical Robustness and Ease of Winding: The rigid, stacked core structure provides good mechanical strength. The bobbin windings are also relatively simple to automate, facilitating production.
Common Applications
Due to their low cost and reliable performance for standard requirements, EI-core transformers are ubiquitous in:
1. Power Supplies for consumer electronics, appliances, and low-power industrial equipment.
2. Audio Equipment such as amplifiers and mixers (for impedance matching and isolation).
3. Control Circuits and general-purpose low-voltage applications.
