Non-destructive testing of tubes and wires - using inductive probe with passive elements providing compensation for unbalance

摘要

The non-destructive testing of welded or drawn tubes or wires to detect fissures is performed using Foucault currents induced from an inductive probe. Passive elements provide compensation for probe unbalance. A sinusoidal voltage generator (1) is coupled to probe (2) comprising primary winding (9) with secondary windings (7, 8) wound on it. This probe assembly fits over tube under test. Both secondary windings have equal turns. Any unbalance of probe assembly during manufacture is compensated for by passive network (3) with variable transformers permitting adjustment for zero output. Probe output (10) is amplified (4) for phase or amplitude detection of fault conditions.