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Installation Rekommendations
Keep signal cables and power supply cables as far apart as possible. Cable grooves
separating signal cables and power supply cables are strongly recommended. If signal
cables and power supply cables cross, they should intersect perpendicular to one another.
Signal and power supply cables should not be running parallel to one another in
instrument cabinet inlets. Any risk of electromagnetic incompatibility will be reduced to
a minimum if signal cable inlet and power supply inlet are separated and at opposite
sides of the cabinet. Cables should be properly fastened along the cabinet walls.
When connecting shielded cables with different protector ground points far from each
other, there may be interference problems stemming from differences in potential in the
ground net. This is caused by stray currents between the protector ground points. If this
occurs, the stray current loops have to be cut.
Some measures to cut stray current loops in order of priority are described below.
Insulate the sensor from surrounding metal structures.
Open the cable shield at the transmitter end of the cable and connect a capacitor
(10nF/3000 V) between the cable shield and the protector ground wire. The capacitor
will limit low frequency currents and short circuit high frequency currents.
If the instrument is installed in an EMC-proof cabinet and the cable inlets are properly
done, stray currents may be prevented by cutting the cable shield at the transmitter end
of the cable.
It is improper to connect sparkling lights to the same terminal as the measuring
equipment. Sparkling lights can often generate generates very high levels of EMI when
turned on/off.
Frequency converters are also very often causes of EMI, especially the older types
which is not CE-marked. It is therefore not recommenced to install measuring
equipment nearby frequency converters.
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