How to Test a Rogowski Coil?

A Rogowski coil is a flexible air-core current transducer for measuring AC, transient and high-frequency currents. It features no magnetic saturation, wide bandwidth and easy installation. Standard testing is required before delivery and use to guarantee measurement accuracy and stability. This guide summarizes the streamlined testing procedure, key items and acceptance criteria.

1. Working Principle

A Rogowski coil outputs a voltage proportional to the current's change rate (di/dt). It must pair with an integrator to restore the original current waveform. All tests verify the coil's voltage output, phase, frequency response and linearity to eliminate assembly, position and parameter errors.

2. Pre-Test Preparation

2.1 Required Equipment

• Programmable AC current source
• High-precision oscilloscope
• Calibrated reference current probe
• Matching integrator module
• Multimeter and insulation resistance tester

2.2 Visual Inspection

Check the coil for cracks, deformation and shielding damage. Ensure tight docking with no gaps, intact cables and connectors, and consistent model and parameter specifications.

3. Standard Test Items & Procedures

3.1 Continuity & Insulation Test

Steps: Measure coil winding resistance with a multimeter to rule out open/short circuits. Test insulation resistance between winding and shielding layer.

Criteria: Resistance conforms to factory standards; insulation resistance ≥100MΩ, no electric leakage or interference risks.

3.2 Waveform & Phase Test

Steps: Clamp the coil and reference probe on the same conductor, output standard sine-wave current, and compare the two waveforms via oscilloscope.

Criteria: Undistorted coil voltage waveform; phase error within allowable tolerance.

3.3 Accuracy & Linearity Test

Steps: Under fixed power frequency (50/60Hz), test current points of 20%, 50%, 80%, 100% and 120% rated range, record data and calculate errors.

Criteria: Full-scale error within ±1% (or customized standard); smooth linearity without obvious deviation.

3.4 Frequency Response Test

Steps: Keep current amplitude stable, adjust frequency across the coil's rated bandwidth, and record amplitude and phase errors.

Criteria: No excessive amplitude attenuation or phase shift; stable signal output within the full rated bandwidth.

3.5 Position Sensitivity Test

Steps: Test current at conductor center, offset and edge positions to check error fluctuation.

Criteria: Position-caused errors meet on-site installation tolerance requirements.

3.6 Integrator Matching Test

Steps: Connect the coil with the matched integrator, input standard current, and verify restored current waveform and amplitude.

Criteria: Complete, undistorted output waveform with negligible delay and accurate amplitude.

4. Common Faults & Troubleshooting

• Waveform distortion: Loose docking or poor wiring; re-fit coil interface and check connections.
• Large measurement error: Conductor offset or mismatched integrator; center the conductor and recalibrate parameters.
• High-frequency attenuation: Unmatched bandwidth or overlong cables; optimize wiring and matching accessories.
• No output signal: Open circuit or power failure; check coil winding and integrator power supply.

5. Acceptance Standards

A qualified Rogowski coil shall have intact appearance and structure, qualified insulation and continuity, undistorted waveform and stable frequency response, compliant accuracy and linearity, and good integrator matching performance.

6. Summary

Rogowski coil testing covers basic electrical performance, waveform characteristics, accuracy and environmental adaptability. Standard testing and regular calibration ensure reliable measurement in power systems and industrial testing applications.For more information, please contact us at sales@xfullstar.com