Proposed Change to the Test set-up for IEC 61000-4-4
Aim of this document is to inform about the proposed change to the test set-up for EFT/Burst
tests in Edition 2 of IEC 61000-4-4.
Present standard IEC 61000-4-4
The test setup for EFT/burst testing which is specified in the present IEC 61000-4-4 is
technically not correct.
The device under test (EUT) is placed on a non-metallic table and the test generator
including the coupling/decoupling network is located on the reference ground plane on the
floor.
This means that there is no sufficient rf current path back to the generator. The stray
capacitance from the EUT being setup on the table to the reference ground plane on the floor
is very small (some 10pF) and therefore the coupling effect is very small.
Comparing the test set-up to the present version of IEC 61000-4-6 the difference becomes
very clear.
As per IEC 61000-4-6 the EUT and at least the CDN’s must be located directly on the ground
reference plane to ensure a good return path for the rf current injected into the EUT.
Test_setup_IEC_61000-4-4_ed2.doc
29.06.04
New IEC 61000-4-4 edition 2
In November 2003 a new draft revision (CDV) of IEC 61000-4-4 was accepted by positive
voting of the national committees.
The new revision of IEC61000-4-4, which is called IEC 61000-4-4 edition 2, takes care of the
problem and has changed the specification of the test set-up accordingly.
Ground reference plane
l = length between clamp and the EUT to be tested, should be 0.5m +/-0.05m
Figure 7a − General test set-up for laboratory type tests
For table top equipment the ground reference plane is now located on the test table (there is
no longer a non-metallic table specified). The EUT and the test generator including the CDN
is located above the ground reference plane.
!!!! The EFT/burst generator and the CDN are no longer located on the floor of the
laboratory. The operator must no longer sit down or knee down to the floor for conducting the
test. There is now a well defined current return path between EUT and CDN. The test setup’s as per IEC 61000-4-4 and IEC 61000-4-6 are now harmonized.
Test_setup_IEC_61000-4-4_ed2.doc
29.06.04
Please refer to the original text of IEC 61000-4-4 edition 2
7.2
Test set-up for type tests performed in laboratories
7.3
Test conditions
EUTs, stationary floor-mounted, table top, and equipment designed to be mounted in other
configuration, shall be placed on a ground reference plane and shall be insulated from it by an
insulating support 0,1 m ± 0,01 m thick (see Figure 7a)."
In the case of table-top equipment, the EUT should be located 0,1 m ± 0,01 m above the
ground reference plane (see Figure 7a). Equipment normally mounted on ceilings or walls
shall be tested as table-top equipment with the EUT located 0.1m +/- 0.01m above the ground
reference plane.
The test generator and the coupling/decoupling network shall be placed directly on, and
bonded to, the ground reference plane.
All cables to the EUT shall be placed on the insulation support 0,1 m above the ground
reference plane. Cables not subject to electrical fast transients shall be routed as far as
possible from the cable under test to minimise the coupling between the cables.
The connection impedance of the coupling/decoupling network earth cables to the ground
reference plane and all bonding shall provide a low inductance.
Examples of the test set-up for laboratory tests are given in Figures 7a and 7b.
In Figure 7b, an additional ground plane, connected to the chassis of the EUT is used.
NOTE The clamp may be mounted on the wall of a shielded room or any other grounded surface and bonded to
the EUT. For large, floor standing systems with cables exiting at the top, the clamp could also be centred 10 cm
above the EUT and have cables drop through the centre of the plane.
Figure 7b – Example of a test set up for rack mounted equipment
Test_setup_IEC_61000-4-4_ed2.doc
29.06.04