EMC-PARTNER CDN2000-06-25, Руководство пользователя

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CDN2000-06-25 coupling decoupling network
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Superimposing surge onto power supply
To superimpose the surge pulses onto power line supply, coupling filters must be used. The aim of the
coupling filter is to couple the generated surge waveform without deformation of rise time, half value time
and amplitude onto the operated EUT and to protect the auxiliary equipment from surge pulses.
When surges are superimposed onto power supply lines, the synchronisation angle must be chosen to
correspond to the half wave of the power supply. The picture below shows that pseudo tests can be carried
out, when the synchronisation angle is not correctly selected. When a positive surge is superimposed at
270°, the clamping voltage of the varistor is not reached and no real test is carried out.
Figure: 1.0.1-3
1.1.2 Ring wave test 0,5 µs / 100 kHz
Introduction:
The ring wave is a typical oscillatory transient, induced in low voltage cables due to the switching of
electrical networks and reactive loads, faults and insulation breakdown of power supply circuits or lightning.
The ring wave is representative of a wide range of electromagnetic environments of residential, as well as
industrial, installations; it is suitable for checking the immunity of equipment in respect of the above
mentioned phenomena.
Another cause of the ring wave, lightning, is characterised by a unidirectional waveform (standards 1,2/50;
8/20 µs); the circuits subjected to its indirect effect ( inductive coupling among lines) are mainly influenced
by the derivative of the primary pulse; the coupling mechanism, from its original frequency spectrum, gives
rise to oscillations, the characteristics of which depend on the reactive parameters of the ground circuits, on
metal structures involved in the lightning current flow, in addition to the propagation in the low voltage lines
involved (see figure below).
Protection circuit
Tester
Filter
Coupling
Superposing sure at
different angle