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China CT3 Series Current Transformers - Reliable Suppliers from a Leading Factory for Power System Protection

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A current transformer (CT) is a crucial component in electrical engineering, designed for effective control, monitoring, and protection of power systems. This device transforms massive alternating currents (AC) into small, measurable levels, ensuring safety and precision in various applications. In the realm of power production, transmission, and distribution, as well as industrial settings, high-current power circuits are commonly integrated with safety relays and sensitive measuring devices. As a leading supplier from China, our factory specializes in manufacturing high-quality current transformers to meet the needs of diverse industries. Trust our expertise and commitment to excellence for all your current transformer requirements.

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    Product Details

    ⚙ Product Overview

    A CT operates on electromagnetic induction and has two windings: a primary winding with a few turns linked in series to the high-current circuit, and a secondary winding with many turns connected to safety or measurement devices. The primary winding receives a significant current, whereas the secondary winding — which is normally tuned to 5A or 1A for most industrial applications — receives very little current.

    This proportionality, also known as the transformation ratio, allows for accurate current measurement while safeguarding workers and equipment from potentially hazardous voltages.

    • 🔌 High Insulation
      Sufficient insulation to maintain high voltage between windings.
    • 📈 High Linearity
      Minimizes measurement error for reliable readings.
    • ⚡ High Precision
      Designed for accurate energy metering in industrial use.
    ⚠️

    Important: When using a CT, never leave the secondary winding open circuit. An open circuit may produce extremely high voltages, which can seriously damage electrical equipment and pose safety hazards.

    Since they enable more precise current monitoring and improved issue detection, current transformers are crucial to ensuring the reliability, efficiency, and safety of modern electrical systems.

    📋 Technical Parameters

    🔌 Outline Size Reference (mm)
    Type Specification (mm) Outline Size
    A B C D E F M
    CT3-100 100A / 100mA 118 60 30 108 18 20 c4*7
    CT3-250 250A / 100mA 136 64 35 123.5 22 25 c4*7
    CT3-400 400A / 100mA 180 93 40 165.5 32 35 c4*7
    CT3-630 630A / 100mA 212 102 40 198 43 41 c4*7
    Accuracy Grade: 0.5  |  Lead Length: 1 m Overload Current: ≥ 1.2% ln

    ❓ Frequently Asked Questions

    Q What is the basic 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 current in the secondary winding is proportional to the primary current, allowing safe and accurate measurement.
    Q Why should the secondary winding of a CT never be left open circuit?
    Leaving the secondary winding open circuit can generate extremely high voltages across it. This is dangerous as it can damage the CT, connected equipment, and pose a serious safety risk to personnel. Always ensure the secondary winding is connected to a burden or short-circuited when not in use.
    Q What is the standard secondary output current for industrial CTs?
    For most industrial applications, the secondary winding of a CT is standardized to output either 5A or 1A. This standardization allows the safe connection of measuring instruments and protection relays regardless of the primary current level.
    Q What does the accuracy grade 0.5 mean for the CT3 series?
    An accuracy grade of 0.5 means that the CT has a maximum ratio error of ±0.5% under specified conditions. This level of accuracy is suitable for energy metering and billing applications where precise current measurement is essential.
    Q What is the overload current specification for the CT3 series?
    The CT3 series is rated for an overload current of ≥ 1.2% of the rated current (ln). This means the transformer can handle currents exceeding its rated value by at least 20% without significant degradation in performance or accuracy.
    Q How do current transformers contribute to electrical system safety and reliability?
    Current transformers isolate high-voltage circuits from measuring instruments and personnel, enabling safe monitoring of large currents. They provide precise data for protection relays, energy meters, and fault detection systems — all of which are critical to maintaining the reliability, efficiency, and safety of modern electrical infrastructure.