Installation and Maintenance
5.1 Installation
SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5
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Connect self inductances to a suppression circuit. Self-
inductance in relays and fans etc. produces disturbance
voltages that are far higher than the operating voltage.
These disturbance voltages can influence electronic
devices. The disturbance voltages cause by inductors
must be limited at the emission source by connecting
suppression circuits (diode or RC circuit). Only use
suppressors that are intended for use with your relay or
fan.
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Switching cubicle illumination
Use light bulbs for the switching cubicle illumination, e.g.
LINESTRA lamps. Avoid the use of luminescent lamps
because these produce noise fields. If you cannot avoid
using luminescent lamps, the measures described in
Figure 5-1 will be necessary.
5.1
Installation
5.1.1
Installation instructions
Electromagnetic compatibility
Electromagnetic compatibility involves all questions regarding electric, magnetic
and electromagnetic emission effects. To avoid disturbing influences on electrical
installations, these effects must be reduced to a minimum. The construction of
device, correct connection of bus lines and the suppression of self inductances are
essential limitation measures. See also the note in section 4.2.1 (protecting against
lightning strikes).
Suppression of self inductances
Figure 5-1
Measures to suppress
luminescent lamps in a
cubicle
Arrangement of devices and cables
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Maintaining clearance to reduce noise
A both simple and effective way of reducing disturbing influences is to maintain
clearances between the culprit and victim device or cable. Inductive and capacitive
disturbances decrease with the square of the distance between the elements
involved. This means that doubling the distance reduces the effect of the
disturbance by a factor 4. If "geographic" considerations are taken into account in
the planning of a building or a cubicle, these measures can usually be implemented
very cheaply.
5
Installation and Maintenance
5