Accurate current measurement is crucial in electrical engineering. At Smilics Technologies, we've been perfecting our sensor solutions to the highest quality standards since manufacturing our first split-core current transformer in 1994 and our first Rogowski Coils over 15 years ago.
Do you know the differences between these two solutions?
Two popular devices used for this purpose are Current Transformers (CTs) and Rogowski Coils. This article aims to highlight the differences, advantages, and disadvantages of these two devices.
Current Transformers (CTs)
CTs operate on the principle of magnetic induction, translating high-current signals into lower, safe levels suitable for metering devices or protective relay equipment.
Advantages of CTs
- Measurement accuracy: TCs are able to measure more accurately, especially at low current intensities. In the case of Smilics CTs we reach class 0.2s.
- Protection: CTs provide necessary input signals for protective relays, allowing them to disconnect circuits when fault conditions occur.
- Load Balancing: By accurately measuring the load current, CTs aid in balancing the load across phases, thereby improving system efficiency.
Disadvantages of CTs
- Saturation Limitation: CTs may saturate when exposed to high levels of current, leading to measurement inaccuracies.
- Measuring current ranges: The measuring current ranges are lower, due to the limited space of the winding.
- Dimensions: TCs are considerably larger and heavier.
Rogowski Coils
Named after Walter Rogowski, these coils are used for the measurement of alternating current (AC) or high-speed current pulses.
Advantages of Rogowski Coils
- Versatility: the same sensor can be used for any range and it is not necessary to design sensors according to the amperage of the installation.
- Saturation Limitation & Wide Range: RCs do not saturate and can therefore measure any current range, even short circuits.
- Size and Flexibility: Rogowski coils can be made smaller, lighter, and are flexible, allowing them to be wrapped around conductors of any shape.
Disadvantages of Rogowski Coils
- Accuracy: Rogowski coils have lower accuracy compared to CTs. Typically reach class 0.5
- Installation: although their installation is very simple, they are more sensitive to the position of the conductor and to nearby electromagnetic fields.
- Need for Integrator Circuit: To obtain the current waveform, the output of the coil must pass through an integrator circuit.
In conclusion, both CTs and Rogowski coils have their unique advantages and disadvantages. The choice between the two depends on the specific requirements of the application. While CTs are more suitable for applications requiring high accuracy, Rogowski coils are more suited for applications requiring flexibility and a wide measurement range.
Whatever solution best suits your needs, at Smilics Technologies we have standard and customised solutions for whatever your needs may be.
Find out more on our website www.smilics.com or contact us.
