Laminated Transformers

Introduction:
Laminated transformers, the most common type of transformer, are made by stacking punched strips of iron or nickel that serve as the core of the transformer. Laminated transformers are less expensive than both the R-Core and toroidal construction transformers and can be designed to meet all types of agency approvals (UL, CSA, VDE).

Typical Applications:
The laminated construction is often used in isolation transformers, step-up and step-down transformers, autotransformers, power supplies, test and measurement instruments, industrial controls, power transducers, audio amplifiers, voice and music reproduction equipment, telephone communication networks, and lighting controls.

Electrical Characteristics:
The gauge (4 mil to 25 mil) and grade (M-55 to M-6) of the laminations are used to control core loss and exciting current.

Silicon laminations, both grain oriented and non-oriented steel, as well as 50% to 80% nickel laminations are used to meet different permeability requirements.

Primary and Secondary windings can be constructed as concentric windings, side by side windings on a 3-flange bobbin, or wound on two separate bobbins to control leakage inductance and winding capacitance.

For high-voltage applications or high breakdown voltage requirements, layer wound laminated transformers are cheaper than toroids and most other constructions.

Custom Magnetics typically produces laminated transformers between 1 mW and 2,000 W. The normal frequency range is 25 Hz to 400 Hz for power applications and 20 Hz to 20,000 Hz for audio applications.

Physical Characteristics:
Laminated transformers are available in several shapes including: Long E, EE, EI, UI, L, and J. Typical sizes range from 1/4" cube to 8" cube. Many types of standard mounting styles are available. Laminated transformers can be designed with fly leads, solder lugs, or printed circuit board pins.

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