Conducted Immunity (CDN BCI/CCL)

Conducted immunity testing is performed on all electric and electronic equipment having at least one conducting cable (such as mains supply, signal line or earth connection). The effect of conducted disturbing signals, induced by electromagnetic radiation, is tested by injecting the signal via special coupling units to the cabling.

The source of disburbance is basically an electromagnetic field, coming from intended RF transmitters, that may act on the whole length of cables connected to installed equipment. The dimensions of the disturbed equipment, mostly a sub-part of a larger system, are assumed to be small compared with the wavelengths involved. The in-going and out-going leads: e.g. mains, communication lines, interface cables, behave as passive receiving antenna networks because they can be several wavelengths long. Between those cable networks, the susceptible equipment is exposed to currents flowing through the equipment. Cable systems connected to equipment are assumed to be in resonant mode ( /4, /2 dipoles) and as such are represented by coupling and decoupling devices having a common-mode impedance of 150 Ohm with respect to a ground reference plane.

This test method subjects the EUT to a source of disturbance comprising electric and magnetic fields, simulating those coming from intentional RF transmitters. The disturbing fields ( E and H) are approximated by the electric and magnetic near-fields resulting from the voltages and currents caused by the test set-up. The use of coupling and decoupling devices to apply the disturbing signals to one cable at a time, while keeping all other calbes non-excited, can only approximate the real situation where disturbing sources act on all cables simultaneously, with a range of different amplitudes and phases.

When performing the tests it is required that the EUT and possible auxiliary equipment are exercising all normal modes of operation. The test results may be classified on the basis of the operating conditions and functional specifications of the EUT, according to the following performance criteria:

• (A) Normal performance within the specification limits;
• (B) Temporary degradation or loss of function or performance which is self-recoverable;
• (C) Temporary degradation or loss of function or performance which requires operator intervention or system reset;
• (D) Temporary degradation or loss of function or performance which is not recoverable, due to damage of equipment (components) or software, or loss of data.