The problem of size [EMC testing]

Some systems, such as telephone exchanges, are simply too large or too complex to undergo EMC testing in the normal way. Three main problems exist with the EMC Directive for large systems. First, the size of the open area test sites recommended in existing standards is often too small for large systems. Secondly, there is a requirement to vary the position of the cables attached to the equipment under test (EUT) to maximise emissions. Finally, standards require the rotation of the equipment under test to maximise the emissions measured. This would prove difficult in the case of a physically large system and its associated cabling. The limitations of existing standards has been recognised by the European telecoms industry, and a new standard covering the measurement of emissions from large telecoms systems has been published. This standard is ETS 300 127 (1994), published by the European Telecommunications Standards Institute (ETSI), and it may be used to demonstrate compliance to the EMC Directive