These are electrical devices used to measure alternating current. They produce a proportional secondary current in their output. However, revenue grade CTs are specially made to give highly accurate and reliable output typical of commercial and industrial applications, normally meant for billing and metering purposes.
Types of Revenue Grade CTs
Split Core Current Transformers
The core of a split core CT is designed to open and close around a conductor without disconnecting the conductor from the circuit. They, therefore, offer flexibility for their installation, making them quite suitable for retrofitting applications. They usually find application where it’s not possible to isolate the circuit for installing the CT. One of the most common usages of the split core CTs’ convenience is where minimal disruption needs to be achieved.Advantages
• Easy installation and maintenance
• No need to open the circuit
• Suitable for retrofit installations
Applications
• Building energy management systems
• Sub-metering
• Load monitoring
h5>Solid Core Current Transformers Solid core CTs are designed with a solid core that is not designed to be opened. They are more accurate and stable, generally, than split core CTs due to their nature. However, they typically require that a circuit be deenergised in order that the CT may be placed around the conductor.
<Advantages
• High accuracy and stability
• Less prone to errors compared to split core CTs
Applications
• Utility metering
• High-accuracy energy measurement
• Power distribution systems
NATA Tested Current Transformers
The NATA tested current transformers are certified to meet standards and accuracy limits. The testing by the National Association of Testing Authorities guarantees these current transformers to provide a reliable and accurate measurement suitable for revenue billing and critical measurement applications.Advantages
• Certification ensures high accuracy and reliability
• Complies with national and international standards
• Suitable for regulated billing applications
Applications
• Metering of electricity for billing
• Compliance with regulatory standards
• High-stakes energy management
Billing Current Transformers
Billing CTs are designed particularly for the purpose of billing and revenue. It provides accuracy and reliability of electrical consumption measurements. These CTs have to meet rigid standards of accuracy to ensure that the billing is impartial and accurate.Advantages
• High accuracy suitable for financial, billing applications
• Reliable performance for financial transactions
• Compliance with utility regulations
Applications
• Commercial and industrial billing systems
• Electricity sales and distribution
• Energy accounting
Metering Current Transformers
Metering CTs are used along with energy meters and they make sure the measurement of electrical current with an extremely high degree of accuracy. They find major applications in applications that require very precise monitoring and analysis of electrical consumption.Advantages
• Highly accurate for exact energy metering
• For a wide range of metering applications
• Normally used with digital meters
Applications
• Energy management systems
• Industrial process monitoring
• Grid management
Ceramic Cased Current Transformers
Ceramic-cased CTs have ceramic materials casing, providing excellent insulation and high-temperature resistance. These CTs are extremely robust, reliable, and resistant to challenging environments. In continuous operation, they can bear all sorts of adversities.Advantages
• High mechanical strength and resistance to high temperatures
• Good electrical insulation
• Long lifespan under difficult conditions
Applications
• Industrial harsh environment
• High-temperature applications
• Outdoor installation
Revenue-grade current transformers are required for accurate electrical measurement and billing. Knowing what kinds are available—split core, solid core, NATA tested, billing, metering, and ceramic cased CTs—makes a lot of difference in picking the right CT for any particular application. Each has different advantages and is ideal for different modes of installation and operation. Proper choice of CT enables proper measurement, reliable billing, and effective energy management for any business or utility.
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