Why is there a high minimum current required for a clamp meter to measure frequency in addition to current?

Question

Modern clamp meters use hall effect sensors to measure AC and DC current and normally calculate True-RMS. But for the meter to display the frequency of the measured current some require significant current to be flowing.

For example for the Fieldpiece SC680

Frequency (Hz) Through Clamp

Minimum current range: >7AAC (10 to 100Hz); >20AAC (100 to 400Hz) on 100AAC range; >25AAC (10 to 400Hz) on 600AAC range.

Why is this?

Answer 1

You need sufficient current to generate a large enough magnetic field around the conductor to induce a voltage into the AC clamp sensor.