EMC-PARTNER CDN2000-06-25, User Manual

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CDN2000-06-25 coupling decoupling network
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A dc source charges the impulse capacitor Cs to a programmed voltage. The high voltage switch S links
impulse capacitor to the impulse shaping network. Depending on energy and voltages it can be a
mechanical or an electronic switch. The waveform is mainly influenced by the network of the generator.
Voltage and Current waveform and tolerances
t t
Figure: 1.0.2-3
Relevant parameters for testing.

Repetition rate
The repetition rate of the transient is directly related to the frequency of occurrence of the primary
phenomenon; it is higher whenever the primary cause is the load switching in control lines, and less frequent
in the case of faults and lightning; the occurrence may range from 1/s to 1/month

Phase angle
Equipment failures related to ring wave on power supply sources can depend on the phase angle of the a.c.
voltage sine wave at which the transients are applied. When a protection element sparks over during a ring
wave test, power-follow might occur. Power-follow is the current from the connected power source that flows
through a protective element, or from any sparkover in the EUT, during and following the passage of test
discharge current.
For semiconductors, the phenomenon appears related to conduction state of the EUT semiconductor
devices at the time the ring wave occurs. Semiconductors parameters that might be involved include
forward and reverse recovery characteristics and secondary breakdown performance.
The device most likely to fail in a phase-related way are semiconductors involved in the power input
circuitry. Other devices, in different areas of the EUT, might also exhibit such failure modes in the EUT
power-input circuits, if some or all of the transient pass through them.

Polarity reversal
The sensitivity of semiconductors to the timing and polarity of a transient is one of the reason for selecting
an oscillatory waveform to represent the environment; it will be more likely to provoke undue semiconductor
failures than an unidirectional wave.
The breakdown of semiconductors under various conditions of load and transient overvoltages applications
has been investigated.
The results below are related to the effect of transient polarity reversal on diode e.g. 1N679. The ring wave
has been applied to the diode at the peak of the reverse voltage and the measured average breakdown
voltage resulting being 1'800 V. The application of the ring wave at 30° and 90° after start of conduction has
given a reduction of the average breakdown voltage of about 33% and 50% respectively.
Rise time:
Ts < 1µs
Decaying:
2. Amplitude to 1.
60 to 90 %
Rise time:
Ts=0,5 µs ± 30%
Decaying:
2. Amplitude to 1.
60 to 90 %
A
V
100%
10%
0,5 µs
10 µs ± 20% 10 µs ± 20%
90%