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Ring cores

Ring cores are frequently used for inductors with a defined L value, predetermined frequency stability and thermal and temporal constancy. Medium and high perm manganese-zinc ferrites and medium to low perm nickel-zinc ferrites are the materials used for ring cores.

The recommended materials are:

Frequency range Material
10kHz – 1MHz K2005, K4000, K5500, K6000,K7000, K10000
1MHz – 200MHz K14, K40, K250, K800

Ferrite ring cores are used for highly symmetrical transformers, for impulse and wideband transformers, for common-mode chokes for damping of radio interference and now increasingly also for the development of power transformers.

The following favourable frequency ranges are predetermined for materials K2001, K2004, K2006 and K2008:

Frequency range Material
20 – 100 kHz K2004
50 – 200 kHz K2006
50 – 300 kHz K2008
300 – 1000 kHz K2001

In order to prevent short-circuits when winding and to increase the insulation strength, ring cores can also be supplied with parylene or lacquer coating. Dimensions and insulation of ferrite ring cores are in compliance with IEC 61604.

If not otherwise agreed upon, the following electrical insulation strenght apply to coated toroids:

outer diameter ≤ 10 mm: ≥ 1,0 kV
outer diameter ≤ 20 mm: ≥ 1,5 kV
outer diameter > 20 mm: ≥ 2,0 kV

In the case of AC tests, the insulation strengths apply to the effective value. It complies with IEC 61604.

Nickel-zinc ferrites are supplied without coating due to their high electrical resistance. In contrast, manganese-zinc ferrites can be supplied with parylene or lacquer coating. The layer thickness leads to an enlargement of the outer diameter and the height and to a decrease of the inner diameter and amounts to with parylene approx. 30 – 40 µm as well as with the lacquer approx. 0.3 – 0.6 mm. The applied lacquer usually leads to a loss of permeability, which makes it necessary to expand the AL tolerance values in relation to uncoated cores.

The stated core heights are for orientation and can be changed on request. The guaranteed parameters for power applications apply to the winding data stated by the manufacturer, the predetermined testing frequency, excitation and temperature.

Type Drw.  no. nominal AL values / nH datasheet
K2006 K2008 K4000 K5500 K6000 K7000 K10000
R 2.5/1.5/1 1 410 610 1020 PDF Icon
R 3.5/1.8/2,4 1 530 800 1300 PDF Icon
R 4.1/2.2/1.6 1 780 1150 1950 PDF Icon
R 5,8/3/1.5 1 790 1150 1950 PDF Icon
R 6.3/3.8/2.5 1 1000 1500 2500 PDF Icon
R 8/4/3 1 1650 2450 4150 PDF Icon
R 10/6/4 1 850 900 1600 2200 2450 2700 4050 PDF Icon
R 12.5/7.5/5 1 1050 1150 2000 2800 3050 3300 5100 PDF Icon
R 14/9/5 1 900 1000 1750 2400 2650 2850 4400 PDF Icon
R 16/9.6/6.3 1 1350 1450 2550 3500 3850 4150 6400 PDF Icon
R 19/11/8 1 1800 2000 3450 4800 5250 5650 8700 PDF Icon
R 20/10/7.4 1 2150 2350 4100 5600 6150 6650 10250 PDF Icon
R 21.5/10.3/7.5 1 2200 2400 4150 5750 6250 6850 PDF Icon
R 22/10/6 1 1800 2000 3400 4700 5150 5550 PDF Icon
R 23/14/7 1 1450 1600 2750 3800 4150 4500 PDF Icon
R 25/15/10 1 2100 2350 4050 5600 6100 6600 PDF Icon
R 26/14,5/10 1 2450 2650 4650 6400 7000 7600 PDF Icon
R 27/14.5/8.5 1 2050 2300 3950 5450 5950 6850 PDF Icon
R 28/18/19 1 3500 6700 9200 10050 10900 PDF Icon
R 29/19/7.5 1 1300 2500 3450 3800 4100 PDF Icon
R 30/11.5/5.3 1 2000 3850 4800 5750 6250 PDF Icon
R 31.5/19/12.5 1 2650 5050 6300 7550 8200 PDF Icon
R32.5/13/7 1 2550 4850 6050 7250 7850 PDF Icon
R 34/20.5/12.5 1 2650 5050 6050 7550 8200 PDF Icon
R 36/23/15 1 2800 5350 6700 8050 8700 PDF Icon
R 40/24/16 1 3400 6500 7850 9800 10600 PDF Icon
R 42/26/12.5 1 2450 4650 5850 7000 7600 PDF Icon
R 50/30/20 1 4250 8150 9800 12250 13250 PDF Icon
R 56/32/18 1 4050 7700 9650 11550 12550 PDF Icon
R 58.3/40.8/17.6 1 2600 5000 6250 8150 PDF Icon
R 63/38/12,5 1 2650 5050 6050 8200 PDF Icon
R 80/40/15 1 4350 8300 10500 PDF Icon
R 102/65,8/15 1 2750 5250 6300 PDF Icon
Drawing 1

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