Appendix: Important notes for crane operators and crane operating companies
© 2008 HIRSCHMANN Automation and Control GmbH · Branch Office Ettlingen · eMail: [email protected] · www.hirschmann-usa.com
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50 650 19 0201e_Rev C (LinkBelt278).doc / 2008-08-18 / Rev. C / rk
INSTRUCTIONS 3 Notes on Electromagnetic Compatibility (EMC) in electronic
systems taking account of the effect of electromagnetic fields
Electromagnetic fields are having an increasing effect on electronic systems and may lead to malfunctions; to
avoid these, we have listed preventive measures in the following, according to the latest state of technology:
1. The preventive measures proceed primarily from the basic idea that the electronic circuits should be
shielded from irradiated high frequencies by a closed, low-resistance protective shield against high-
frequency interference.
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All components are equipped with metallic outer housings with grounding option;
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only cables with a braided screen are used. The screen must generously cover all connectors and must
be of high conductivity;
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coupling of the crane earth and the electronics earth in one single point of the system only.
2. The general precautions listed under Section 1 cannot assure complete protection against electromagnetic
fields in all cases, however, since the size and type of effect depend on local conditions.
Examples of such influencing factors are:
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particularly unfavourable arrangement of the aerials in relation to the system,
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very high transmission power,
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consistent compliance with measures of Section 1 not possible due to local conditions,
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long
cables,
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coupling of interference into the supply leads.
In unfavourable conditions, one has no choice but to take experimental measures on site, in addition to the
preventive measures, while taking account of the principles mentioned in Section 1, for example:
•
fitting filters or short-circuiting the interference frequencies using capacitors;
•
establishing or separating earth connections;
•
using a guarded shield system.