EM TEST
EFT 500 Series
Manual for Operation
V 2.00
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3.3.
Coupling decoupling network
The decoupling part of the coupling network has to:
- filter the interference pulses in the direction to the power supply;
- protect other systems that are connected to the same power supply and
- realize a high impedance of the power supply, e.g. battery supply.
3.3.1. Coupling/decoupling network for ac/dc power lines
The coupling network has to couple the interference pulses to the lines of a power supply system (AC or DC). As
coupling devices capacitors of sufficient strength and bandwidth shall be used according to IEC 61000-4-4.
C o u p lin g n e tw o r k a c c . to IE C 6 1 0 0 0 - 4 - 4
L 1
L 2
L
N
C x
C y
P E
C y
L 1
L 2
L E
L
N
P E
E F T 5 0 0
C k
The coupling on signal lines can usually not be effected capacitively without interfering with the signal flow. It is
often impossible to contact the required circuit (direct), e. g. coaxial or shielded cables. In this case the coupling
is realized with the capacitive coupling clamp. The interference simulator can be connected on both sides of the
coupling clamp.
3.3.2. Capacitive coupling clamp
- The coupling clamp is not matched by 50 ohm. If the clamp is matched there exists an additional magnetic
coupling, which may cause completely different test results.
- The clamp should be placed in a distance of 0.5m to the equipment under test. When using shorter distances,
the EUT may be influenced by radiation.
- If the EUT is built up by two different equipment, the test should be conducted on each single equipment with
the required distance.
Generator
EFT 500
EUT 1
EUT 2
Signal
Signal
Ground reference
Capacitive coupling clamp
100 pF
Decoupling
network
Coupling to signal lines or lines where no galvanic
contact is possible (e.g. shielded lines)
0.1m
Decoupling network
Net
Net
0.5m
0.5m
