Stromsonden

Stromsonden, known in English as current probes, are instruments that measure electrical current in a conductor without requiring a direct electrical connection to the circuit carrying the current. They are widely used in laboratory testing, power engineering, motor control, and automotive diagnostics to observe current waveforms, analyze transients, and support protection and power-quality applications.

There are several technologies used in current probes. Rogowski coils are flexible, air‑cored coils that encircle the conductor and sense the rate of change of current; the output is proportional to the derivative of current and requires signal processing to reconstruct the waveform. They offer wide bandwidth and can measure large currents without saturating. Hall-effect probes employ a Hall sensor in a magnetic circuit to produce a voltage proportional to the current’s magnetic field; available as clamp‑on (split-core) devices or inline sensors, they can measure both alternating and direct current and provide galvanic isolation. Current transformers use a magnetic core and secondary winding to generate a scaled voltage for AC currents; they are common in power-distribution, metering, and protection schemes and also provide isolation but are generally limited to AC.

Selection depends on the application: CTs are reliable for AC power measurements; Hall probes suit DC and AC with fast transients; Rogowski coils are useful for high-bandwidth AC measurements and non-contact sensing. Considerations include bandwidth and accuracy, dynamic range, isolation, temperature stability, and integration with measuring instruments.

Stromsonden are integrated into many measurement systems, including oscilloscopes, data loggers, and power analyzers, as well as handheld clamp meters for field use.