EM TEST
UCS 500 Series
Operating Manual
V 5.40
46 / 99
9.4.
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.
9.4.1.
Coupling/decoupling network for ac/dc power lines
The coupling network couples the EFT pulses via 33 nF capacitors onto the AC or DC power lines. As coupling
devices capacitors of sufficient strength and bandwidth shall be used according to IEC 61000-4-4.
The coupling on signal lines can usually not be effected capacitive 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.
Coupling method:
Test duration
: At least 2 minutes in positive and negative polarity. The test duration must be at least as long for
examine all functions of the EUT
Coupling
IEC 61000-4-4 edition 2 (2004) and later versions requires to couple all lines simultaneously in
Common Mode coupling.
This means that a EFT test needs two tests with 60s (positive and negative 60s each).
9.4.2
IEC 61000-4-4 (1995, 2001) requires all line combination to be tested individually.
A 1-phase EUT needs to test all combination L, N, PE, L+N, L+PE, N+PE, L+N+PE each with
two tests with 60s (positive and negative 60s each). Total test time 14 x 60 seconds
9.4.2.
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 the distance is shorter distances, the EUT may be
influenced by radiation.
- If the EUT is includes two separate equipment, the test should be
conducted on each single equipment with the required distance.
9.5.
Burst Test Setup
