O-Core PR

The performance of a toroidal transformer may be further optimized with an O-core (like in O-ring). O cores are wound from a silicon steel strip, which is continuously pointed towards each end to produce a circular cross section.

They are more expensive to produce than regular toroids and inevitably involve some scrap losses when the strip is cut to shape, but on the other hand feature advantages, which sometimes are worth the extra cost.

Why should you consider the O-core:

Get more power in a smaller package and save 10%-15% in magnet wire. The circumference of a circle is about 12% less than that of a square with the same area, and 18% less than a rectangle with the same area and a 1:2 side ratio.

Save the cost of epoxy coating the cores. Epoxy coating adds 20-30 % to the cost of a bare toroid. Taping with 50% overlap is sufficient core insulation because the rounded shape eliminates the risk of edge cut through. The O-cores also eliminates the barrel shape of windings placed on a square core.

Prolong the life of the winding machine. Heavy wire may be wound at reduced tension, reducing the risk of insulation damage and layer cut through.

Alpha-Core now introduces a series of O-cores for power transformers ranging from 12 to 1200VA at 60Hz. They are made of the 0.009" grain oriented silicon steel and may be used safely up to 17kG.

Buy O-cores here!

PN App. VA [60Hz] ID OD Section Diameter Net Cross Section Weight

[mm] [in] [mm] [in] [mm] [in] [sqcm] [sqin] [Kg] [Lb]

OA-10

12-24

32

1.26

64

2.52

16.5

0.65

2.13

0.33

0.26

0.57

OA-20

24-48

35

1.38

72

2.83

18.5

0.73

2.68

0.42

0.37

0.81

OA-30

36-72

38

1.50

75

2.95

20.0

0.79

3.17

0.49

0.42

0.92

OA-40

48-96

40

1.57

80

3.15

21.5

0.85

3.48

0.54

0.51

1.12

OA-50

60-120

42

1.65

86

3.39

23.5

0.93

3.89

0.60

0.65

1.43

OA-80

96-192

45

1.77

92

3.62

25.0

0.98

4.92

0.76

0.79

1.74

OA-100

120-240

48

1.89

98

3.86

26.5

1.04

5.30

0.82

0.95

2.09

OA-120

144-288

50

1.97

105

4.13

27.5

1.08

6.03

0.93

1.15

2.53

OA-150

180-360

52

2.05

108

4.25

29.0

1.14

6.74

1.04

1.27

2.79

OA-200

240-480

55

2.17

115

4.53

31.5

1.24

7.78

1.21

1.57

3.45

OA-250

300-600

58

2.28

122

4.80

33.5

1.32

8.70

1.35

1.84

4.05

OA-300

360-720

58

2.28

128

5.04

35.0

1.38

9.53

1.48

2.03

4.47

OA-400

480-960

62

2.44

134

5.28

37.5

1.48

11.00

1.71

2.53

5.57

OA-500

600-1200

65

2.56

141

5.55

39.5

1.56

12.30

1.91

2.92

6.42

OA-600

720-1440

68

2.68

148

5.83

41.5

1.63

13.47

2.09

3.37

7.41

OA-800

960-1920

72

2.83

157

6.18

44.0

1.73

15.56

2.41

3.99

8.78

OA-1000

1200-2400

75

2.95

166

6.54

47.0

1.85

17.40

2.70

4.84

10.65