What Are The Disadvantages of The Rogowski Coil?

The Rogowski coil is a type of electrical device used for measuring alternating current (AC), particularly in high-current or high-frequency applications. It operates on the principle of electromagnetic induction and consists of a helical coil of wire wound on a nonmagnetic core. When an alternating current flows through a conductor enclosed by the coil, the changing magnetic field induces a voltage in the coil that is proportional to the rate of change of current. This induced voltage is then integrated electronically to provide a signal proportional to the actual current waveform.

Working Principle

The Rogowski coil measures current without direct electrical contact. It functions based on Faraday’s Law of Electromagnetic Induction, which states that a changing magnetic field induces a voltage in a nearby conductor.  
 

Applications

Rogowski coils are widely used in a variety of fields due to their flexibility, wide frequency response, and ease of installation. They are commonly applied in:

Power systems monitoring – For measuring AC currents in power grids, switchgear, and substations without breaking the circuit.

Industrial automation – Used to monitor large AC motors, drives, and power converters.

Transient current detection – Suitable for capturing short-duration pulses or harmonic-rich currents in power electronics and fault analysis.

Metering and protection – Installed in smart meters, protective relays, and monitoring equipment to measure current safely and accurately.

Research and laboratory testing – For experimental setups requiring non-intrusive, wideband current measurements.

Despite these advantages, the Rogowski coil also has several notable disadvantages, which can limit its performance in certain conditions.

Need for an Integrator Circuit
One of the main disadvantages is the requirement for an external or built-in integrator circuit to obtain a signal proportional to current. The coil output is proportional to the derivative of current, not the current itself. This makes the measurement system more complex, as it requires additional electronic components for integration, calibration, and filtering. Any error in the integrator (such as drift, offset, or noise) can directly affect the accuracy of the current reading.

Limited Low-Frequency Performance
Rogowski coils are less effective at measuring low-frequency or direct currents (DC). Since the output voltage depends on the rate of change of current, the signal amplitude decreases as the frequency decreases. At very low frequencies or for DC measurements, the coil provides little or no output, which restricts its use to AC and transient applications only.

Sensitivity to External Noise and Positioning
Because the Rogowski coils has no magnetic core, it can be more sensitive to external electromagnetic interference. Proper shielding and grounding are necessary to minimize noise pickup. Additionally, measurement accuracy depends on the coil’s positioning and how well it encircles the conductor. If the coil is not centered or its loop is not fully closed, errors may occur due to leakage flux or non-uniform magnetic coupling.

Calibration and Temperature Drift
Rogowski coils require periodic calibration to maintain accuracy, especially when used in environments with significant temperature variation. The coil winding resistance and electronic integrator performance can change with temperature, leading to output drift and reduced measurement precision over time.

Mechanical Fragility and Installation Care
Though flexible and easy to install, the coil’s physical construction can be relatively delicate. Excessive bending, stretching, or mechanical stress may damage the winding or insulation, affecting accuracy. Furthermore, if the coil loop does not close properly, the measurement will not be reliable.

Limited Dynamic Range
Compared to traditional current transformers, Rogowski coils may have a lower dynamic range, particularly in detecting both very small and very large currents accurately. Their performance can be limited by the sensitivity of the integrator and the noise level in the system.

Conclusion

The Rogowski coil remains an excellent choice for high-current, wide-frequency, and non-intrusive AC current measurement. Its flexibility, lightweight design, and linear response make it invaluable in power monitoring, industrial systems, and research. However, its disadvantages—including the need for an integrator, low-frequency limitations, and potential noise sensitivity—mean that it must be carefully implemented and calibrated for best performance. In applications requiring DC measurement, very low frequencies, or high precision without electronic compensation, traditional current transformers or Hall-effect sensors may be more suitable.