A study of impulse noise caused by connecting or disconnecting coaxial cable between equipment

This paper describes the characteristics of impulse noise that is generated when a coaxial cable linking pieces of equipment at different ground potentials is connected or disconnected. The potential difference of equipment with a DC power supply system in a telecommunications center is simulated with an experimental model. The measured peak value of the impulse noise current is almost independent of any DC current on the coaxial cable produced by potential differences between the equipment and earth. An analysis model for adopting a SPICE program has been developed and the calculated waveforms agree well with the experimental results. A countermeasure to prevent the impulse noise current is also clarified.