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China Current Transformer Suppliers - Factory Direct AC Measurement Solutions for Power Systems

A current transformer (CT) is a vital component in electrical systems that regulates, monitors, and protects power networks. This technology effectively reduces large alternating currents (AC) into small, manageable measurements. Essential for connecting high-current power circuits to safety relays or delicate measurement devices, current transformers are widely utilized in power generation, transmission, distribution, and various industrial applications. As one of the leading suppliers and manufacturers in China, our factory is dedicated to providing high-quality current transformers that meet the demanding needs of the industry. Experience reliability and efficiency with our expertly crafted CT solutions, designed to enhance your power system's safety and performance
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    Product Details

    Product Overview

    Electromagnetic induction powers a CT, which has two windings: a primary winding with a few turns linked in series with the high-current circuit and a secondary winding with numerous turns connected to safety or measurement devices. The primary winding receives a high current while the secondary winding, which is usually tuned to 5A or 1A for most industrial applications, receives a low current. This proportionality—also referred to as the transformation ratio—allows for accurate current monitoring while shielding workers and equipment from potentially dangerous voltages.

    CTs require sufficient insulation to maintain high voltage between windings, sufficient linearity to minimize measurement error, and high precision for energy metering. When using a CT, the secondary winding should never be open circuit. This is because an open circuit might result in extremely high voltages that could harm electrical equipment. In conclusion, since they enable more precise current monitoring and improved problem avoidance, current transformers are crucial to ensuring the reliability, efficiency, and safety of modern electrical systems.

    • ⚡ Electromagnetic Induction
      Operates via primary & secondary windings using electromagnetic induction principles.
    • 🔒 High Insulation
      Sufficient insulation maintained between windings to handle high voltages safely.
    • 🎯 High Precision
      High linearity and accuracy designed for reliable energy metering applications.
    • 🛡️ Safety Critical
      Secondary winding must never be open circuit to prevent dangerous voltage spikes.

    Technical Parameters

    Type

    Rated Current (A)

    Rated Burden (VA)

    Class

    Rated Voltage (V)

    Rated Frequency (Hz)

    SF45/14

    30/5A~100/5A

    1.5~2.5

    1.0~0.5

    720

    50/60

    SF62/20

    30/5A~200/5A

    1.5~2.5

    3.0~0.5

    720

    50/60

    SF62/30

    100/5A~400/5A

    1.5~5

    1.0~0.5

    720

    50/60

    SF62/40

    200/5A~600/5A

    5~10

    1.0~0.5

    720

    50/60

    SF74/40

    150/5A~600/5A

    2.5~20

    1.0~0.5

    720

    50/60

    SF74/50

    250/5A~1000/5A

    5~20

    1.0~0.5

    720

    50/60

    SF86/60

    250/5A~1200/5A

    5~30

    1.0~0.5

    720

    50/60

    SF104/80

    600/5A~2000/5A

    5~45

    1.0~0.5

    720

    50/60

    SF140/100

    1000/5A~3200/5A

    5~50

    1.0~0.5

    720

    50/60
    Outline Drawing (unit: mm)

    Type

    A

    B

    C

    D

    E

    F

    G

    H

    I

    J

    K

    L

    M

    N

    O

    SF45/14

    65

    30

    30

    53

    68

    15

    45

    SF62/20

    78

    36

    6.6

    36

    55

    71

    30.1

    30.1

    11

    23

    44

    21

    62

    21

    26

    SF62/30

    78

    47

    6.6

    35

    55

    71

    31

    31

    16

    31

    44

    31

    62

    21

    26

    SF62/40

    78

    47

    6.6

    35

    55

    71

    33

    33

    11

    31

    47

    41

    74

    21

    31

    SF74/40

    98

    61

    6.6

    45

    67

    81

    41

    41

    31

    41

    47

    41

    74

    21

    31

    SF74/50

    98

    61

    6.6

    45

    67

    81

    51

    51

    21

    51

    68

    51

    86

    31

    44

    SF86/60

    110

    56

    6.6

    40

    62

    76

    65

    65

    31

    61

    86

    61

    104

    31

    56

    SF104/80

    126

    56

    6.6

    40

    62

    76

    81

    ⚠️ Important Notice: The secondary winding of a current transformer must never be left open circuit during operation. An open circuit can generate dangerously high voltages, potentially damaging equipment and posing serious safety risks.

    Frequently Asked Questions

    Q What is the working principle of a current transformer (CT)?
    A current transformer works on the principle of electromagnetic induction. It consists of a primary winding connected in series with the high-current circuit and a secondary winding connected to measurement or protection devices. The high current in the primary induces a proportionally lower current in the secondary, enabling safe and accurate current monitoring.
    Q What is the standard secondary output current for industrial CTs?
    For most industrial applications, the secondary winding of a current transformer is standardized to output either 5A or 1A, regardless of the primary current level. This standardization allows compatible use with a wide range of measurement and protection instruments.
    Q Why should the secondary winding of a CT never be left open circuit?
    If the secondary winding of a current transformer is left open circuit while current flows through the primary, the magnetic flux becomes unbalanced and generates an extremely high voltage across the secondary terminals. This can result in insulation breakdown, equipment damage, and serious safety hazards to personnel.
    Q What accuracy classes are available for these current transformers?
    The current transformers in this series are available in accuracy classes ranging from Class 0.5 to Class 3.0, depending on the model. Class 0.5 is suitable for precision energy metering, while higher class values are typically used for protection and general measurement purposes.
    Q What rated voltage and frequency do these CTs support?
    All models in this series support a rated voltage of 720V and are compatible with both 50Hz and 60Hz power systems, making them suitable for global industrial applications across different regional electrical standards.
    Q How do I select the right CT model for my application?
    To select the appropriate CT model, consider the following factors: the primary rated current range of your system (e.g., 30/5A up to 3200/5A), the required accuracy class for your measurement needs, the rated burden (VA) of your connected instruments, and the physical dimensions (outline drawing) to ensure compatibility with your installation space.