{"id":49152,"date":"1999-03-15T13:15:00","date_gmt":"1999-03-15T12:15:00","guid":{"rendered":"https:\/\/essmann.com\/archive-1999-information-about-flash-protection-for-vehicle-scales\/"},"modified":"2024-07-30T16:55:55","modified_gmt":"2024-07-30T14:55:55","slug":"archive-1999-information-about-flash-protection-for-vehicle-scales","status":"publish","type":"post","link":"https:\/\/essmann.com\/en\/archive-1999-information-about-flash-protection-for-vehicle-scales\/","title":{"rendered":"Archive 1999: Information on lightning protection for truck scales"},"content":{"rendered":"\n

In the event of<\/strong>direct or nearby lightning strikes to the buildings involved or parts of the weighing system, the possibility of damage cannot be completely ruled out.\nWe recommend installing overvoltage protection for a location where the weighing bridge and weighing house are at risk of being struck by lightning. <\/p>\n\n

Today, modern<\/strong>weighing systems are largely made up of powerful electronic components.\nHowever, this is precisely why they are particularly susceptible to damage caused by lightning strikes and overvoltage in general. <\/p>\n\n

In<\/strong>a joint study with load cell manufacturers and customers, HE W\u00e4getechnik has specifically researched the problem of lightning damage to weighing systems.\nThis information deals with fundamental questions on the subject of lightning protection and the installation of a lightning protection system. <\/p>\n\n

Lightning strike<\/h2>\n\n
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Heat<\/strong>that accumulates on mountain slopes in full sunlight or cold air masses that push warm air ahead of them on their underside in a weather front generate air movements.\nAs the warm air rises, it gradually cools down.\nA cloud is formed from water droplets and, at higher altitudes, from ice crystals.\nA thundercloud is such a system with higher air speeds than is normally the case.\nThe powerful upward and downward currents in the center of the cloud generate static charges, with the ice crystals in the upper layers of the cloud being positively charged and the water droplets in the lower layers being negatively charged. <\/p>\n<\/div><\/div>\n\n

The<\/strong>voltage field generated between the charge centers causes the air molecules to ionize, creating a conductive channel that enables the discharge, i.e. the lightning.\nMost lightning flashes are discharges between two clouds.\nAbout 15 % are discharges between cloud and ground.\nIn general, the charge concentration is highest at high or pointed points.\nTherefore, lightning between cloud and ground preferably strikes masts, towers, trees, etc.\nOnce the ionization channel is established between the cloud and the ground, a conductive path is created that short-circuits the charge centers, thus enabling the main current flow or return stroke and restoring the balance between the charges.\nThis current can induce voltages in power supply systems such as long (underground) cable runs parallel to the ground.\nStudies have shown that a lightning strike within 300 m of the geometric center of a weighbridge is certain to have a damaging effect on it.\nFurthermore, damage is not limited to lightning strikes to earth, as cloud-to-cloud lightning can also generate a sufficiently strong electromagnetic pulse to cause damage.\nLightning strikes are discharge surges where the current and voltage are considerably higher than normal. <\/p>\n\n

Damage caused by lightning strikes<\/h2>\n\n

At the heart of<\/strong>modern load cells are foil-like strain gauge resistors.\nThese strain gages are manufactured by coating an epoxy or polyamide carrier with a thin film.\nA load cell normally consists of four (or a multiple of four) strain gages in the form of a Wheatstone bridge configuration.\nSeveral resistors are connected in series with the supply lines of the Wheatstone bridge. <\/p>\n\n

These<\/strong>resistors compensate for temperature influences and are used to calibrate the load cell output signal.\nStrain gages and resistors can only withstand low voltages of no more than 15 or 20 volts.\nThe dielectric strength of the foil carrier is approx. 400 to 500 volts.\nOvervoltage or overcurrent caused by lightning will destroy the load cell either: by damaging the resistors or strain gages, or by damaging the foil carrier that connects the bridge to the housing<\/em>. <\/p>\n\n

In<\/strong>both cases, the component may burn out completely, but not necessarily.\nIt is possible that only a part of the load cell circuit or the bonding of one of the strain gages is damaged.\nIn this case, the scale begins to work incorrectly and\/or does not return to zero after being loaded.\nSometimes these problems only occur weeks after the lightning strike!\nIn addition to the load cells, damage can also occur to the measuring device (display unit\/computer) and peripheral devices such as printers and card readers, especially if live cables have been struck in the immediate vicinity.\nAs with the load cells, only a small part of the electronics may be damaged, such as RS232 connections or even just a few small tantalum capacitors.\nMinor damage that is overlooked immediately after the lightning strike can cause a display error.\nIt is therefore essential to inspect the circuit boards carefully for damage or residues of burnt-out components. <\/p>\n\n

Lightning protection<\/h2>\n\n

A distinction is<\/strong>made between external and internal lightning protection.\nWith external lightning protection, there is normally an earth connection between the steel roof of the control room in which the display unit is installed or another nearby structure or a high protective mast, so that a preferred discharge point is available via which the overvoltage is safely conducted to earth.\nThis external lightning protection is quite controversial.\nOn the one hand, a weighbridge or weighbridge in general is not a particular point of attraction for lightning strikes, but a 20 meter high mast has an attraction radius of 81 meters. This means that lightning that would strike a building or a tree at a distance of 60 m or more without such a mast will inevitably generate a surge (step voltage) in the immediate vicinity of the weighbridge!\nWithout very strict precautions, such a surge will cause an electromagnetically induced pulse that can undoubtedly cause serious damage to the weighbridge. <\/p>\n\n

\"\"<\/figure>
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Effective heightof the structure (m)<\/td>Attractionradius (m)<\/td><\/tr>
5<\/td>30<\/td><\/tr>
10<\/td>50<\/td><\/tr>
15<\/td>67<\/td><\/tr>
20<\/td>81<\/td><\/tr>
25<\/td>95<\/td><\/tr>
30<\/td>108<\/td><\/tr>
35<\/td>132<\/td><\/tr>
40<\/td>155<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div><\/div>\n\n

The table above shows<\/strong>the radius of attraction of a structure at a certain effective height for downward strokes.\nMasts to protect the weighbridge offer the only advantage that the lightning does not strike the weighbridge directly, but actually increase the risk of damage due to their lightning-attracting effect. <\/p>\n\n

Internal<\/strong>lightning protection consists of the creation of potential equalization within the entire substation through the use of protective devices and the construction of the weighbridge structure in the form of a Faraday cage.\nA Faraday cage is also built around the control room or measuring cabin.\nA relatively short distance between the two cages requires an earth connection, i.e. the potential of the entire system is always constant.\nEquipotential bonding is already included as standard in every HE W\u00e4getechnik truck scale. <\/p>\n\n

All<\/strong>external connections, such as AC lines, communication connections and the signal\/feed line, are a potential source of power surges and short-term overvoltages.\nIt is therefore essential to install an overvoltage protection device at the input of the Faraday cage for each input or output line to ensure lightning protection. <\/p>\n\n

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To<\/strong>protect the load cells against step voltages, insulation is provided against the ground and the scale bridge.\nAlthough this ensures a high level of protection, it must be borne in mind that the load cell circuit can still theoretically be carried through and damaged by high currents induced by lightning.\nHowever, the occurrence of such a high potential difference that the foil carrier between the strain gauge and the housing can be damaged is unlikely.\nThe insulating plates only fulfill their function if they are well protected against moisture; as soon as the plates are flooded, the insulation resistance drops drastically.\nTherefore, good care and cleaning of the scales also protects against damage caused by lightning! <\/p>\n<\/div><\/div>\n\n

Links to the topic<\/h3>\n\n

Lightning information service from Siemens<\/strong><\/a>with BLITZ-SPION – the free overview of current thunderstorm activity.<\/p>\n\n

www.blitz-radar.de<\/strong><\/a>offers thunderstorm warnings with notification via SMS or email (free of charge)and archive data retrieval on lightning strikes from a specific day (subject to charge).<\/p>\n

\n
\n\n

Association of German Lightning Protection Companies<\/strong><\/a>inform about lightning protection systems and specialist dealers.<\/p>\n\n<\/div>\n<\/div>\n

Dehn + S\u00f6hne<\/a><\/strong>offers a complete, coordinated product range for lightning and surge protection.<\/p>\n","protected":false},"excerpt":{"rendered":"

In the event ofdirect or nearby lightning strikes to the buildings involved or parts of the weighing system, the possibility of damage cannot be completely ruled … <\/p>\n

Read more<\/a><\/p>\n","protected":false},"author":7,"featured_media":48609,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","_seopress_titles_title":"Still valid today: Protection against lightning damage in weighing systems","_seopress_titles_desc":"In this article from 1999, you will learn how surge protection can effectively prevent lightning damage to sensitive weighing systems.","_seopress_robots_index":"","_jet_sm_ready_style":"","_jet_sm_style":"","_jet_sm_controls_values":"","_jet_sm_fonts_collection":"","_jet_sm_fonts_links":"","activitypub_content_warning":"","activitypub_content_visibility":"","activitypub_max_image_attachments":4,"activitypub_interaction_policy_quote":"anyone","activitypub_status":"federate","footnotes":""},"categories":[176,172,147],"tags":[209,174],"class_list":["post-49152","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-history","category-truck-scales-weighbridges","category-uncategorized","tag-history-of-scale-construction","tag-truck-scales","infinite-scroll-item","masonry-post","generate-columns","tablet-grid-50","mobile-grid-100","grid-parent","grid-33"],"_links":{"self":[{"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/posts\/49152","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/comments?post=49152"}],"version-history":[{"count":1,"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/posts\/49152\/revisions"}],"predecessor-version":[{"id":49153,"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/posts\/49152\/revisions\/49153"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/media\/48609"}],"wp:attachment":[{"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/media?parent=49152"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/categories?post=49152"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/essmann.com\/en\/wp-json\/wp\/v2\/tags?post=49152"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}