What are Current Transformers?

Current transformers are one of the fundamental components used in electrical systems and are used to measure, isolate, or convert high currents into lower, measurable values in circuits carrying high current. These devices play a significant role, especially in large industrial facilities, power grids, and energy generation plants. Current transformers, also known as current transducers, are widely used in the field of electrical engineering. So, how do these current transformers work and why are they so important?

Basic Operating Principles of Current Transformers

Current transformers reduce high currents to lower, measurable levels. In this way, high currents in electrical circuits can be safely monitored and measured. Busbar-type current transformers are used for this purpose in large systems.

The current passing through the primary winding of a current transformer creates a magnetic field, and while this magnetic current passes through the primary winding, lower currents are induced in the secondary winding. This current in the secondary winding is usually connected to measuring devices or relays for safe monitoring.

Types of Current Transformers

Current transformers are classified into different types according to their areas of use and functions. Here are the most commonly used types of current transformers:

1. Measuring Current Transformers

These types of transformers are used to measure current in the circuit. They are preferred for monitoring the current in power grids or industrial plants. The current passing through the secondary circuit is directed to measuring devices. These devices are generally used with electricity meters to accurately measure energy consumption.

2. Protective Current Transformers

These transformers are used for protection purposes, specifically to detect overcurrents in the circuit. They protect electrical systems against overloads and short circuits. Oil-type and dry-type current transformers are the main types used for protection.

3. Low Power Current Transformers

Low power transformers are typically used in small-scale electronic devices that require precise measurements. In this type of transformer, the winding through which current flows is adjusted with much greater sensitivity.

Applications of Current Transformers

Current transformers have a wide range of applications. These devices typically play a critical role in large electrical systems.

1. Energy Distribution Systems

Current transformers are used in energy distribution systems to measure and monitor electric current. In large power lines, currents can be reduced to a safe level with current transformers to enable measurement.

2. Industrial Facilities

In industrial facilities, industrial transformers are used in electrical systems to monitor and protect motors and generators. The current from the secondary circuit is directed to control panels to ensure system safety.

3. Electricity Meters and Energy Management Systems

Current transformers used in electricity meters are used to monitor energy consumption. In these types of transformers, the primary winding wound around a core enables current measurement.

Advantages and Disadvantages of Current Transformers

As with any electrical device, current transformers have both advantages and disadvantages.

Advantages

• Safe Measurement: Reduces the current passing through the circuit to a safe level, allowing for safe monitoring of electrical circuits.

• Provides Protection: Ensures that protective relays activate during overcurrent situations.

• Energy Efficiency: Helps improve energy efficiency in enterprises by monitoring energy consumption.

Disadvantages

• Accuracy Class: Low-quality devices may not provide accurate measurements.

• Limited Power Capacity: Very high-power systems may require more specialized transformers.

Selection Criteria for Current Transformers

There are several important factors to consider when choosing a current transformer:

1. Current Rating

The maximum current level in the circuit to which the transformer will be connected is a critical factor in the selection of the device. Transformers wound in the opposite direction to the primary winding can manage high currents more efficiently.

2. Accuracy Class

The accuracy class represents the measurement sensitivity of the current transformer. Devices with high accuracy classes should be selected depending on the area where the measurement will be made.

3. Physical Size

The physical dimensions of the current transformer should match the size of the installation area. The magnetic current in the secondary winding is an important factor affecting the size of the device.

4. Environmental Conditions

It is important that transformers are suitable for the environmental conditions in which they will operate. Transformers that will operate under challenging conditions such as high temperature, humidity, or dusty environments must be resistant to these factors.

Conclusion

Current transformers are critical devices that enhance the safety and efficiency of electrical systems by ensuring the safe and accurate measurement of high currents.

Choosing the right current transformer improves both energy management and system safety. When selecting a current transformer suitable for the system's needs, factors such as current capacity, accuracy class, and environmental conditions must be thoroughly evaluated.