Current Transformer (CT) - Resin Cast vs Tape Wound: A Comprehensive Comparison

Resin Cast CTs

Overview

Resin Cast CTs are encapsulated in a high-quality epoxy resin, which provides excellent mechanical strength and insulation. These CTs are typically used in environments where durability and reliability are critical.

Advantages

• Enhanced Insulation: The resin provides high dielectric strength, ensuring better performance under high voltage conditions.
• Moisture Resistance: Resin encapsulation prevents moisture ingress, making them ideal for humid or outdoor environments.
• Durability: These CTs are robust and resistant to mechanical impacts and environmental factors.
• Compact Design: Resin casting allows for a smaller footprint, useful in confined spaces.
• Maintenance-Free: The solid encapsulation minimizes the need for regular maintenance.

Applications

• Power distribution systems
• High-voltage switchgear
• Industrial plants
• Outdoor installations

Tape Wound CTs

Overview

Tape Wound CTs consist of a core wound with a specific number of turns of tape or wire. These CTs are typically used in low- to medium-voltage applications.

Advantages

• Customizable: Tape Wound CTs can be easily tailored to specific ratios and applications.
• Cost-Effective: These CTs are generally more economical compared to Resin Cast CTs.
• Lightweight: They are lighter and easier to handle.
• Flexible Design: Suitable for irregular shapes and retrofitting into existing systems.

Applications

• Panel boards
• Control systems
• Relay protection circuits
• Metering in low-voltage environments

Resin Cast vs Tape Wound: Key Differences

CT Accuracy Classes

The accuracy class of a CT determines its ability to reproduce the primary current accurately in its secondary circuit. This is critical for applications such as metering and protection.

Common Accuracy Classes

• Class 0.2: Offers high accuracy suitable for metering critical loads and where billing precision is paramount.
• Class 0.5: Adequate for general metering and less stringent accuracy requirements.
• Class 1: Suitable for applications where moderate accuracy is acceptable, often used in protection systems.

Choosing the Right CT

When selecting a CT, consider the following factors:

• Application: Identify whether it’s for metering or protection.
• Accuracy Class: Higher classes for metering, lower for general protection.
• Environmental Conditions: Resin Cast CTs are better for harsh environments, while Tape Wound CTs suit controlled indoor settings.
• Cost Constraints: Tape Wound CTs are more economical for basic applications.
• Voltage Levels: Match the CT type with the system’s voltage requirements.

Conclusion

Resin Cast and Tape Wound CTs cater to different operational needs and environments. Resin Cast CTs are durable, reliable, and ideal for challenging conditions, whereas Tape Wound CTs offer flexibility and cost advantages. Understanding the accuracy classes further ensures the selection of the right CT for precise metering and effective protection. Always consider application-specific requirements to make an informed decision.

For high-quality CTs, visit Best of Electricals to explore a wide range of options and make your purchase online with confidence.