Application areas:
Measuring-level current transformer used in power system, transformer used on precision measuring instruments (such as watt-hour meter).

According to the requirements of different measurement accuracy of the transformer, different soft magnetic materials can be chosen as iron core materials. The higher the permeability of the iron core is, the smaller the measurement error of the transformer is, hence the accuracy is higher. At present, the most common iron core material is cold-rolled silicon steel sheet, followed by Permalloy and nano-crystalline glass alloy.

In recent years, demands for transformers with high-precision level (such as class 0.2, class 0.2Sand class0.5S) increased rapidly. When small ratio, low ampere turns are required or the iron core is restricted because of the small volume, the cold-rolled silicon steel often fails to meet the accuracy requirements. Although the Permalloy iron cores with high permeability can meet the required precision, its price is very high.

However use of nano-crystalline alloy iron cores can both meet the accuracy requirements and be produced at lower cost than the Permalloy. Therefore, the demand of measuring level current transformer iron core made of nano-crystalline alloy rapidly increased domestically.

The typical parameters comparison of the common soft magnetic materials used for current transformer iron cores:

Basic parameters
Nano-crystalline iron core
Permalloy (1J85) iron core
Silicon steel iron core

Saturation magnetic flux density (Bs)
1.25T
0.75T
2.03T

Initial permeability (¦Ì0)
8¡«12, 104
5¡«8, 104
103

Maximum permeability (¦Ìm)
60, 104
60, 104
4, 104

Curie Temperature (¡æ)
570
400
740

Density (g/cm3)
7.25
8.75
7.65

Lamination factor
0.7
0.9
0.95

Thickness (mm)
0.03
0.15
0.3


Features:

It is made of the iron-based nano-crystalline strips with a moderate saturation magnetic induction, high permeability and low loss, which can effectively reduce ratio difference angle difference of the transformer. The saturation magnetic induction Bs of nano-crystalline alloy is between the silicon steel and Permalloy.

The lower the Bs value is, the lower the security coefficient of the instrument is. When the system failure occurs and large current through the current transformer results therefore, the iron core is more easily filled, and the secondary current no longer increases in proportion, as can assure that the secondary instruments are well protected and not to be damaged. Permeability of nano-crystalline alloy is close to Permalloy and a magnitude higher than silicon steel, so it is suitable to be made as high-precision transformer iron core.

The density and lamination coefficient of nano-crystalline is lower than that of Permalloy, under the condition of the same size and similar performance of the two. In this case the nano-crystalline iron core is 1/4 lighter in weight, and 1/3 lower in the manufacturing cost. In addition, the linear range of nano-crystalline alloy is wider than that of Permalloy .It can work for a long time at temperature of -55 ~ 130 ¡æ ,with a good temperature stability.


Specifications

a. Rectangular core: (mm)

Iron Core Size(mm)
(mm)

The case size(mm)
Weight of the iron Core

(kg per piece)
Turns Ratio

N1: N2
Excitation current(mA)
Excitation voltage(mV)

55*97/77*119, 25
50*92/82*114, 30
0.53
1:1
25
0.45

95
2.2

1500
53

70*90/100*120, 30
65*85/105*125, 36
0.81
1:1
200
15

1:1
500
50

75*95/105*125, 25
70*90/110*130, 30
0.7
1:1
70
2

1:1
175
8

80*95/120*135, 25
75*90/125*140, 30
1.09
1:1
80
1.7

1:1
600
41

90*90/160*160, 30
85*85/165*165, 36
2.4
1:1
100
6

1:1
500
100

1:1
1000
140

135*135/260*260, 10
130*130/265*265, 16
2.3
1:1
100
1.5

1:1
500
32

82*602/138*658, 45
75*595/145*665, 55
8.8
1:1
100
1.2

1:1
1000
45

1:1
2000
120


b. Ring core:
No.
The iron Core Size
Case size(mm)
The weight of the iron core (kg per piece)
Turns ratio N1: N2 is 1:1; Input current (mA), 50Hz; Output voltage (mV)

1
1105/1165, 15
1095/1175, 25
8.35
Excitation current
450
1200
2000


Excitation voltage
0.59
2.36
5.28


2
415/520, 15
409/526, 23
6.08
Excitation current
50
250
700


Excitation voltage
0.4
3
11


3
305/490, 15
299/496, 23
9.1
Excitation current
350
900
¡¡


Excitation voltage
5
20
¡¡


4
315/395, 35
309/401, 43
8.2
Excitation current
120
400
¡¡


Excitation voltage
3
11
¡¡


5
198/248, 30
192/254, 37
2.76
Excitation current
100
200
500
1000

Excitation voltage
2
6
35
90

6
198/248, 20
192/254, 27
1.84
Excitation current
100
200
500
1000

Excitation voltage
1.5
3.5
25
60

7
155/200, 30
150/205, 36
2
Excitation current
100
190
1000


Excitation voltage
2.5
9.5
80


8
140/180, 30
135/185, 36
1.58
Excitation current
40
80
240


Excitation voltage
1
2.9
15


9
130/190, 30
125/195, 36
2.38
Excitation current
40
80
240


Excitation voltage
1.2
3.8
17


10
100/140, 30
95/145, 36
1.19
Excitation current
30
120
500


Excitation voltage
0.85
6.8
68


11
90/130, 30
85/135, 36
1.09
Excitation current
30
120
500


Excitation voltage
0.7
6
55


12
90/125, 25
85/130, 31
0.78
Excitation current
30
120
500


Excitation voltage
0.9
7
70


13
80/120, 30
75/125, 36
0.99
Excitation current
200
500
¡¡


Excitation voltage
20
65
¡¡


14
85/115, 30
80/120, 36
0.74
Excitation current
30
120
500


Excitation voltage
0.7
6.5
55


15
85/125, 20
80/130, 26
0.7
Excitation current
30
120
500


Excitation voltage
0.62
5.5
50.



wooden case+carton box.