Description
1. Current Transformers (CTs)
Description:
Current Transformers (CTs) are used to measure high current levels by stepping them down to a lower, manageable value that can be safely handled by measurement and protection devices. They are essential for the monitoring and protection of power systems.
Features:
- Accuracy: High precision for accurate measurement and protection.
- Ratio: Step-down current ratio (e.g., 1000:5 A).
- Burden: Ability to drive a specified load without significant accuracy loss.
- Saturation: Designed to prevent core saturation at high fault currents, maintaining accuracy.
- Types: Wound, bar, and toroidal CTs.
- Insulation: Typically insulated with oil, resin, or gas for medium and high voltage applications.
- Safety: Built-in features to safely manage high current levels.
2. Voltage Transformers (VTs)
Description:
Voltage Transformers (VTs), are used to step down high voltage levels to a lower voltage for metering and protection purposes. They provide an accurate representation of the primary voltage for the secondary circuit.
Features:
- Accuracy: High precision to ensure reliable voltage measurement.
- Ratio: Step-down voltage ratio (e.g., 110kV:110V).
- Burden: Ability to drive connected loads without significant voltage drop.
- Insulation: Typically use oil, resin, or gas insulation for high voltage applications.
- Safety: Designed to isolate secondary circuits from high voltage primary circuits.
- Types: Electromagnetic VTs for standard applications, and precision VTs for metering.
3. Capacitive Voltage Transformers (CVTs)
Description:
Capacitive Voltage Transformers (CVTs) use a capacitance divider to step down high voltage levels. They are particularly suited for high voltage applications and offer advantages in terms of cost and performance at very high voltages.
Features:
- Accuracy: Suitable for both metering and protection, though generally less precise than electromagnetic VTs for metering.
- Capacitance Divider: Uses a series of capacitors to achieve voltage reduction.
- Frequency Compensation: Often includes compensation networks to improve accuracy over a range of frequencies.
- Insulation: Typically involves high-voltage capacitors and oil or gas insulation.
- Coupling: Can be used for carrier communication by coupling high-frequency signals onto the transmission line.
- Cost-Effectiveness: More economical at very high voltages compared to electromagnetic VTs.
4. Inductive Voltage Transformers (IVTs)
Description:
Inductive Voltage Transformers (IVTs) are a type of voltage transformer that use electromagnetic induction to step down high voltage levels. They are similar to conventional VTs but are often optimized for specific high voltage applications.
Features:
- Accuracy: High precision for accurate voltage measurement.
- Ratio: Step-down voltage ratio (e.g., 400kV:110V).
- Insulation: Typically use oil, resin, or gas for high voltage insulation.
- Design: Robust design to withstand high voltage stresses and environmental conditions.
- Applications: Commonly used in high voltage transmission and distribution systems.
- Safety: Ensures isolation between primary high voltage and secondary low voltage circuits.
