Which device is commonly used to measure AC current flow in large diameter conductors?

The most suitable device for measuring AC current flow in large diameter conductors is a clamp-on type ammeter. This instrument is specifically designed to measure electric current without requiring direct contact with the conductor. It works by using a magnetic field generated around the conductor when current flows through it. The clamp-on ammeter surrounds the conductor, allowing it to measure the AC current based on this magnetic field, which is particularly useful for large conductors where it may be impractical or unsafe to disconnect the circuit for measurement.

Using a multimeter may not be feasible for large conductors as it typically requires breaking the circuit to connect in series, which can be cumbersome and unsafe in high-current applications. A digital voltmeter is designed to measure voltage, not current, and likewise, an oscilloscope is primarily used for analyzing waveforms and signals rather than measuring current directly. Therefore, the clamp-on ammeter is the most effective and practical choice for this specific application.