Epcos AG issues 5 standard sizes of EFD (Economic Flat Transformer Design) configured ferrite cores made of power ferrite brands N87, N97, N92, N49 and also of high-permeability ferrite brand N30.
An advantage of using EFD-configured cores is a possibility to construct on their basis low height profile compact transformers based on traditional row machine winding.
Small height of finished ferrite transformers and chokes provides a high mechanical stability of wrap-in products made on basis of EFD-cores and gives a possibility to use frames intended for surface mounting.
Find Epcos EFD cores in our stock
Geometrical Dimensions
| Standard Size | A [mm] | B [mm] | C [mm] | D [mm] | h1 [mm] | h2 [mm] | E [mm] |
| EFD 10/8/5 | 10,5±0,3 | 2,7±0,1 | 7,65±0,25 | 4,55±0,15 | 5,2±0,1 | 3,75±0,15 | 1,45±0,05 |
| EFD 15/8/5 | 15,0±0,4 | 4,65±0,15 | 11,0±0,35 | 5,3±0,15 | 7,5±0,15 | 5,5±0,2 | 2,4±0,1 |
| EFD 20/10/7 | 20,0±0,55 | 6,65±0,15 | 15,4±0,5 | 8,9±0,2 | 10,0±0,15 | 7,7±0,25 | 3,6±0,15 |
| EFD 25/13/7 | 25,0±0,65 | 9,1±0,2 | 18,7±0,6 | 11,4±0,2 | 12,5±0,15 | 9,3±0,25 | 5,2±0,15 |
| EFD 30/15/9 | 30,0±0,8 | 9,1±0,2 | 22,4±0,75 | 14,6±0,25 | 15,0±0,15 | 11,2±0,3 | 5,1-0,4 |
Information on boobin and clamps issued by Epcos AG for EFD cores may be accessed by opening pdf files specified in tables shown above.
Lepcos Co. recommends also to use with EFD-configured ferrite cores made by Epcos AG, additional list of bobbin and clamps from other companies.
Designation in Design Documentation
Example of EPCOS code explanation and designation in design documentation:
N87 EFD15/8/5 A=160nH B66413-U160-K187
Measurement unit — piece
B66413 — code of EFD15 core standard size
U160 — execution with gap A=160 nH
K — value of variation for coefficient of single-turn inductance Аl (±10%)
87 - material brand (N87)
Example of Assembling a Magnetic Circuit Set
Example of assembling a magnetic circuit set from EFD-configured ferrite cores.
Additional Information
To decrease losses on transportation and storage, it is recommended (as possible) to order EFD cores and clamps in multiples of amounts contained in factory package. Information on number of cores in standard factory foam plastic package is given in here.
