Introduction

When it comes to measuring electrical parameters in power electronics applications, two popular options are current transformers (CTs) and shunt resistors. Both these devices have their pros and cons and are used depending on the application requirements. In this article, we'll compare these two devices and try to understand which one is better suited for different applications.

Current Transformers

A current transformer (CT) is a device that measures current flow in an electrical circuit. The CT consists of a primary winding through which the current flows and a secondary winding that is used to measure the current flow. CTs are used to measure AC current in power systems and are commonly used in power generators, transformers, and other high-power applications.

The main advantage of CTs is their high accuracy, as they are specifically designed to sense and measure current with high precision. They are also non-invasive and do not require breaking the circuit to measure current. However, CTs are limited to measuring only AC current, and their size can be an issue in some applications.

Shunt Resistors

A shunt resistor is a low resistance resistor that is placed in series with an electrical circuit to measure the current flowing through it. The voltage drop across the resistor is measured, and the current is calculated using Ohm's law. Shunt resistors are commonly used in low power systems, as they are inexpensive and have a small form factor.

The main advantage of shunt resistors is that they can measure both AC and DC current. They also have a low cost and are readily available. However, their accuracy is lower compared to CTs, and they can cause a voltage drop in the circuit, leading to power loss.

Comparison

When it comes to accuracy, CTs score over shunt resistors as they are specifically designed to sense and measure current with high precision. CTs are also non-invasive, which makes them a better option when the circuit cannot be broken. However, CTs only measure AC current and have a bigger form factor.

Shunt resistors, on the other hand, have a lower accuracy compared to CTs, but their small form factor and low cost make them ideal for low power applications. They can also measure both AC and DC current, making them a versatile option.

Conclusion

In conclusion, both current transformers and shunt resistors have their pros and cons, and the choice depends on the application requirements. CTs are ideal for high-power systems where accuracy is crucial, but their size and inability to measure DC current limit their usage. Shunt resistors are inexpensive, versatile, and can measure both AC and DC current, but their accuracy is lower compared to CTs.

We hope this article helps you understand the differences between CTs and shunt resistors and helps you choose the right device for your application.

References

• "Current Transformers." Electrical4U, 24 Apr. 2021, electrical4u.net/current-transformers.

• "Shunt Resistor Basics - Electronic Control Devices." Electronic Control Devices, 30 May 2021, ecdi.com/resources/blog/shunt-resistor-basics.