CT-PT Analysis

As per guidelines and procedures set forth by the International Electrotechnical Commission (IEC) and the Institute of Electrical and Electronics Engineers (IEEE), CT-PT analysis refers to the measurement and analysis of current transformers (CTs) and potential transformers (PTs) used in electrical power systems.

There are some challenges in the CT-PT analysis market in Bangladesh, such as the lack of well-equipped testing facilities, trained professionals, and awareness among end-users about the importance of regular testing. To overcome these challenges-

ICONIC Engineering, is the Only accredited Lab by NABL in Bangladesh who have the ability to provide the service of CT-PT Analysis as they have also the only authorization in Bangladesh is giving the best solution for CT-PT Analysis which is meeting the National goal bonded by the Government.

Introduction

Definition of CT-PT analysis:

As per guidelines and procedures set forth by the International Electrotechnical Commission (IEC) and the Institute of Electrical and Electronics Engineers (IEEE), CT-PT analysis refers to the measurement of current transformers (CT) and potential transformers (PT) used in power systems. Current transformers are used to measure the

Figure: PT analysis

current flowing through a conductor, while potential transformers are used to measure the voltage across a conductor.CT-PT analysis is used in a wide range of power systems, including high-voltage transmission systems, industrial power systems, and distribution systems.

CT-PT analysis involves performing various tests to ensure that these transformers are functioning properly and are calibrated correctly. The tests typically include checking the transformer ratios, polarity, insulation resistance, and burden, among others.

The results of CT-PT analysis are used to ensure the accuracy of the measurements taken by the transformers, which are critical for the safe and efficient operation of power systems.

Importance of CT-PT analysis in electrical power systems:

CT-PT analysis is important in electrical power systems as it ensures accurate measurements of current and voltage as per IEEE C57.13, which are critical for the safe, reliable, and efficient operation of the system. It helps prevent electrical accidents, optimize power generation and delivery, ensure compliance with regulatory requirements, and identify faults and failures in transformers for timely maintenance.

Therefore, CT-PT analysis is essential for the overall performance and stability of power systems.

Objectives of CT-PT analysis:

• • Ensure accurate measurement of current and voltage
  • Detect faults and failures in CTs and PTs
  • Ensure compliance with regulatory requirements and industry standards
  • Optimize the performance of power systems
  • Ensure the reliability of power systems

Foundations of CT-PT Analysis

Understanding CTs and PTs:
Current Transformers (CTs): CTs are used to measure high currents in electrical power systems. They work by transforming the high current flowing through a conductor into a lower current that can be safely measured by instruments, meters, or protection relays. CTs are typically used in conjunction with protective relays, which detect faults and tripping the circuit breakers to isolate the faulty part of the system.

Potential Transformers (PTs): PTs are used to measure high voltages in electrical power systems. They work by transforming the high voltage across a conductor into a lower voltage that can be safely measured by instruments, meters, or protection relays. PTs are typically used to step down high voltages to levels that can be safely measured by meters or instruments, such as voltmeters.

CT-PT Ratio:
CT-PT ratio refers to the ratio of the primary current or voltage to the secondary current or voltage of a CT or PT. This ratio is a critical parameter of CTs and PTs, as it determines the accuracy of the measurements taken by these transformers.

The CT-PT ratio is typically expressed as a fraction or a ratio, where the numerator represents the primary current or voltage and the denominator represents the secondary current or voltage. For example, a CT-PT ratio of 500/5 means that the primary current is 500 amps, and the secondary current is 5 amps.

Difference between CT & PT:

Figure: Difference between CT & PT

Different CT-PT Analysis Tests offered by ICONIC Engineering:

As per the Standards of IEEE C57.13, IEC 61869, ANSI/IEEE C57.13.6, IEC 60044, IEEE C37.110, ANSI C12.20, NEMA SG-4 & ICONIC Engineering can detect a variety of issues, including overloads, short circuits, phase imbalances, and other types of electrical faults that can lead to power system disruptions or damage.

Polarity Test:

A polarity test is used to determine the direction of the current or voltage in a transformer's primary and secondary windings. ICONIC Engineering follows the standards of IEC 60044-1, NSI/IEEE C57.13.1, BS 7626 in terms of the Polarity test that the polarity of a CT or PT be correct within a specified tolerance range, typically ±5% or ±10% of the nominal voltage or current. The test is conducted to verify that the transformer is wired correctly and that the polarity markings on the transformer match the actual connections.

During the polarity test, a known voltage or current is applied to the primary winding, and the resulting voltage or current on the secondary winding is measured. The polarity of the secondary voltage or current is compared to the polarity markings on the transformer to ensure that they match.

Ratio Test:

The ratio test in CT-PT analysis is used to determine the turn ratio between the primary and secondary windings of a transformer. ICONIC Engineering maintains the standards of IEC 60044-1, IEEE C57.13 in terms of the Ratio test of a CT or PT being determined with uncertainty not exceeding 0.5% for CTs and 0.2% for PTs. This test is important to ensure that the transformer is operating at the correct voltage or current levels, and to identify any potential issues with the transformer's performance.

The ratio test involves applying a known voltage or current to the primary winding and measuring the resulting voltage or current on the secondary winding, and then calculating the ratio between the two.

Magnetization Curve Test:

The magnetization curve test is used to measure the magnetizing characteristics of a transformer. ICONIC Engineering follows the standards of IEC 61869-2, IEEE C57.13.1, BS 7626, ANSI/IEEE C57.13.6, and IEC 60044-6 in terms of the Magnetization Curve test. This test is conducted to verify that the transformer is capable of operating within its specified range and to identify any potential issues with the transformer's performance.

The test involves applying a gradually increasing voltage or current to the transformer's primary winding and measuring the resulting magnetic flux density in the core.

Burden Test:

The burden test in CT-PT analysis is used to determine the impedance or burden of a current transformer. ICONIC Engineering follows the standards of IEC 61869-2, IEEE C57.13.1, BS 7626, ANSI/IEEE C57.13.3, and IEC 60044-1 in terms of the Burden test. This test ensures that the CT is accurately measuring the current flowing through the power system and identifies any potential issues with the CT's performance.

The test involves applying a known voltage to the secondary winding of the CT and measuring the resulting current output. The ratio of the voltage to the current output provides the impedance or burden of the CT, which can then be compared to the manufacturer's specifications to verify that the CT is operating correctly.

Phase Error Test:

Phase error test is used to measure the phase angle between the primary and secondary windings of a transformer. ICONIC Engineering follows the standards of IEC 61869-2, IEEE C57.13.1, BS 7626, ANSI/IEEE C57.13.3, and IEC 60044-1 in terms of Phase Error test. It ensures that the transformer is accurately measuring the voltage or current in the power system and identifies any potential issues with the transformer's performance.

The test involves applying a known voltage or current to the primary winding and measuring the resulting voltage or current on the secondary winding. The phase angle between the two is then calculated and compared to the manufacturer's specifications to verify that the transformer is operating correctly.

Saturation Test:

A saturation test in CT-PT analysis is used to determine the level of saturation in a transformer's core. ICONIC Engineering follows the standards of IEC 61869-2, IEEE C57.13.1, BS 7626, ANSI/IEEE C57.13.3, and IEC 60044-1 in terms of Phase Error test. This test is important to ensure that the transformer is not operating in a saturated state, which can cause inaccuracies in the voltage or current measurements.

The test involves applying a gradually increasing voltage or current to the transformer's primary winding and measuring the resulting voltage or current on the secondary winding.

What ICONIC Engineering ensures the Advantages of CT-PT Analysis:

• Assists in accurately measuring and monitoring electrical parameters in power systems
• Provides reliable data for protection and control devices such as relays and meters
• Improves power quality analysis and enables better power system planning and optimization
• Assists in identifying faults, errors, or anomalies in the system, enabling prompt corrective actions
• Increases the overall efficiency and reliability of the power system
• Enables safe and effective operation of electrical equipment and devices
• Reduces maintenance and repair costs by detecting and addressing issues early on.

Standards for CT-PT Analysis

1. IEEE C57.13
2. IEC 61869
3. ANSI/IEEE C57.13.6
4. IEC 60044
5. IEEE C37.110
6. ANSI C12.20
7. NEMA SG-4

Conclusion

CT-PT analysis is an essential technique for maintaining the reliability and safety of electrical power systems. ICONIC Engineering is providing accurate measurements of electrical currents and voltages, enabling engineers to detect potential issues and take corrective action to prevent damage to the system.

With the increasing demand for electricity and the growing complication of power systems, the importance of CT-PT analysis will only continue to grow in the years to come. By utilizing this technique, engineers from ICONIC Engineering can ensure that power systems operate efficiently and effectively, providing the reliable energy supply needed for modern life.

FAQ (Frequently Asked Questions)

Q: What is CT-PT analysis?

A: CT-PT analysis is a technique used in the electrical power industry to measure and analyze electrical currents and voltages.

Q: What is the purpose of CT-PT analysis?

A: The primary purpose of CT-PT analysis is to ensure that the electrical power system is functioning properly, and to detect and diagnose any faults or abnormalities that may occur.

Q: How is CT-PT analysis performed?

A: CT-PT analysis is typically performed by placing current transformers and potential transformers at strategic points in the power system to measure the electrical currents and voltages.

Q: What are the benefits of CT-PT analysis?

A: The benefits of CT-PT analysis include the ability to provide accurate measurements of electrical currents and voltages, the ability to detect potential problems and take corrective action, and the ability to ensure the safe and efficient operation of the power system.

Q: Why is CT-PT analysis important?

A: CT-PT analysis is important because it helps to maintain the reliability and safety of electrical power systems, which are essential for modern life. Without CT-PT analysis, power systems would be more prone to failures and damage, leading to potential power outages and other disruptions.

Q: How often should CT-PT analysis be performed?

A: The frequency of CT-PT analysis depends on the specific power system and the needs of the engineers responsible for monitoring it. CT-PT analysis should be performed on a regular basis to ensure that the system is functioning properly.