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China YK Series Current Transformer - Reliable Suppliers for Industrial Power Monitoring from Our Factory
Product Overview
A CT is powered by electromagnetic induction and consists of two windings: a main winding (few turns connected in series with the high-current circuit) and a secondary winding (many turns connected to safety or measurement devices). While the primary winding receives a large current, the secondary winding, which is typically specified at 5A or 1A for the majority of industrial applications, receives a low current. This proportionality, sometimes referred to as the transformation ratio, protects personnel and equipment from potentially dangerous voltages while enabling precise current measurement.
CTs need strong insulation to sustain high voltage between windings, good linearity to reduce measurement error, and high precision for energy metering. When employing a CT, the secondary winding should never be open-circuited. This is due to the possibility that an open circuit might produce extremely high voltages that could damage electrical equipment. In summary, because they provide more precise current monitoring and improved fault protection, current transformers are essential for guaranteeing the dependability, effectiveness, and safety of contemporary electrical systems.
CTs need strong insulation to sustain high voltage between windings, good linearity to reduce measurement error, and high precision for energy metering. When employing a CT, the secondary winding should never be open-circuited. This is due to the possibility that an open circuit might produce extremely high voltages that could damage electrical equipment. In summary, because they provide more precise current monitoring and improved fault protection, current transformers are essential for guaranteeing the dependability, effectiveness, and safety of contemporary electrical systems.
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Important Safety Notice: The secondary winding must never be left open-circuited during operation. An open circuit can generate extremely high voltages, potentially causing severe damage to equipment and posing serious safety hazards.
Technical Parameters
| Type | Main Loop Current | (mm) Outline Size | ||||
|---|---|---|---|---|---|---|
| YK-30 | < 63A | 30 | 89 | 70 | 28 | 80 |
| YK-45 | < 100A | 45 | 104 | 85 | 28 | 95 |
| YK-65 | < 250A | 65 | 124 | 105 | 28 | 115 |
| YK-80 | — | 80 | 142 | 122 | 28 | 132 |
| YK-100 | < 630A | Current: 1A | 100 | 162 | 142 | 28 | 152 |
| Rated Primary | — | Rated Secondary Current: 0.5mA | ||||
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All outline dimensions are in millimeters (mm). Specifications subject to change without notice.
Frequently Asked Questions (FAQ)
Q
What is a Current Transformer (CT) and how does it work?
A Current Transformer (CT) operates 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 measuring or protection devices). The large primary current induces a proportionally smaller secondary current, allowing safe and accurate measurement of high currents.
Q
Why should the secondary winding of a CT never be left open-circuited?
If the secondary winding is open-circuited while the primary is energized, the transformer will attempt to drive all the primary magnetomotive force through the core, producing an extremely high and dangerous voltage across the secondary terminals. This can damage insulation, destroy the transformer, and pose a serious risk of electric shock or fire.
Q
What are the typical secondary current ratings for industrial CTs?
For most industrial applications, current transformers are specified with a secondary current rating of either 5A or 1A. The YK-100 model in this series, for example, is rated at 1A secondary current, suitable for circuits carrying up to 630A on the primary side.
Q
How do I select the correct CT model for my application?
Selection depends primarily on the maximum primary current of your circuit and the physical dimensions (busbar or cable size) that must pass through the CT window. Refer to the Technical Parameters table above — choose a model whose Main Loop Current rating exceeds your circuit's maximum operating current, and verify that the outline dimensions fit your installation.
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What are the key performance requirements for a current transformer?
A high-quality CT must meet three critical performance criteria: (1) High insulation strength to withstand the high voltage between the primary and secondary windings; (2) Good linearity to minimize measurement errors across the full operating range; and (3) High accuracy to ensure reliable energy metering and protection functions.
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What is the transformation ratio of a CT and why is it important?
The transformation ratio is the proportional relationship between the primary current and the secondary current (e.g., 100A:1A). This ratio is critical because it allows high currents — which would be dangerous to measure directly — to be scaled down to safe, manageable levels for metering instruments and protection relays, while maintaining accuracy and isolating connected equipment from high-voltage circuits.