Northern Connectors Harting DIN 41 612 Connectors - Manual (Page 188)

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EMC housing
EMC with HARTING connectors
HARTING offers metallised D 20 housings and full
metal housings for EMC connectors according to
IEC 60 603-2. Its strong EMI characteristics and
metallised fix ing elements offers optimal shielding
and grounding.
The connection of the cable braid to different types of
connector housings, as well as the influence of
the connector itself on EMC characteristics of an
instrument application, were analysed in regard to the
shielding effectiveness against electromagnetic
radiation. The shielded signal data lines of a railway
application were carried via two eurocard pcb´s
installed into a 19”-rack. The fixing of the cable braid
was realised with different HARTING D 20 hous ings.
The application including the connectors was then
exposed to RF signals, transient bursts and electrostatic
discharges.
The standard plastic housings showed minimal EMC
performance. The EMC performance of metallised and
full metal housings showed significant improvements.
One advantage of metallised housings is their
reduced weight (40 grams compared to 180
grams of a full metal housing). Therefore, minimal
interference is applied to the pcb in applications
where strong vibration is occuring. The HARTING
housings are comparatively light through the use of
metallised plastic.
The main advantages of a full metal housing are
improved cable braid fix ing, easy mounting and
robustness.
In general, one should keep in mind that an unshielded
cable entry leads to loss of the shielding against
elec tromagnetic interference.
“A high-resistance interruption of the cable shield
(e.g. by using “pigtails” via twisted stranded
wires of the cable shield) may affect the EMC
performance and therefore cause unacceptable
effects to the electromagnet ic environment.”
These housings are applied in electronic
installations of the railway vehicles of
the GERMAN RAILWAY. They are also
recommended for stationary installations of
the GERMAN RAILWAY (see norm BN 74016,
part 1 of December 1989).