Description: Hitachi original imported ETP probe: ETP PTH hole probe is Hitachi CMI700/CMI500 instrument specisal probe, durable, test life can reach 80,000-100,000 times, is the Oxford hole copper tester long-term use consumable,ETP probe for CMI700, CMI500 testing gauge. PTH hole copper (ETP) test principle Measured by the principle of eddy current, the ETP probe has a probe, the probe is composed of two coils, when measuring, one of the coils emits electromagnetic field, the free electrons inside the conductor do circular motion in the electromagnetic field, generating a cyclotron current (eddy current), the eddy current generates an electromagnetic field in the direction opposite to the electromagnetic field generated by the coil, received by the other coil. An electrical signal is generated, and the thickness of the hole copper is measured due to the different thickness of the hole copper and the different size of the signal. It can be seen that the electrical cond…