ESD transfer through Ethernet magnetics

Ethernet transceivers are connected to twisted-pair cables by magnetics, which typically contain pulse transformers, common mode chokes, capacitors and resistors. Voltage waveforms on the transceiver-side of magnetics due to electrostatic discharge to the cable-side pins of an integrated Ethernet connector have been measured. 200 m CAT5 unshielded and shielded twisted-pair cables were used. Effect of proximity of the cable to grounded metal carrier in a cable rack was observed. Three methods of discharge to the connector pins are compared: contact-discharge of an ESD-gun, manual discharge of the cables, and cable-discharge using an automatic setup that employs high-voltage relays. The results can also help standardizing the test procedure.