{"id":5841,"date":"2023-05-05T16:06:32","date_gmt":"2023-05-05T08:06:32","guid":{"rendered":"https:\/\/www.ray-tron.com\/?p=5841"},"modified":"2023-09-01T14:00:08","modified_gmt":"2023-09-01T06:00:08","slug":"ele5765","status":"publish","type":"post","link":"https:\/\/www.ray-tron.com\/en\/ele5765\/","title":{"rendered":"How to connect shielded wire How to connect double shielded wire"},"content":{"rendered":"

How to connect the shielded wire: One end of the shielded wire is grounded and the other end is left hanging.<\/p>\n

When the signal line is transmitted over a long distance, the grounding potential at both ends may be different due to the different grounding resistances at both ends or the different currents of the PEN line. At this time, if both ends are grounded, the shielding layer will be energized and interfere with the signal. Therefore, in this case, one point is generally grounded and the other end is left hanging to avoid such interference.<\/p>\n

The shielding effect is better when both ends are grounded, but the signal distortion will increase.<\/p>\n

Please note: The two shields should be isolated shields insulated from each other! If they are not insulated from each other, they should still be considered as a single shield!<\/p>\n

The outermost shielding layer is grounded at both ends due to the potential difference introduced and the induction of the current, thus generating a magnetic flux, reducing the strength of the source magnetic field, thereby basically offsetting the induced voltage when there is no outer shielding layer; the innermost shielding layer is grounded at one end and is only used for general anti-static induction because there is no potential difference. The following specifications are the best proof!<\/p>\n

\"\"

GB 50217-1994 "Design Specifications for Power Engineering Cables" \u2013 3.6.8 Metal Cables for Control CablesShielding<\/a>The grounding method should comply with the following provisions:<\/p>\n

(1) The shielding layer of the analog signal circuit control cable of the computer monitoring system should not form two or more grounding points, and a centralized grounding point should be adopted.<\/p>\n

(2) Except for the control cable shielding layer that needs to be grounded at one point in cases such as (1), when the electromagnetic induction interference is large, it is advisable to use two-point grounding; when the electrostatic induction interference is large, one-point grounding can be used.<\/p>\n

When double-layer shielding or composite overall shielding is used, it is advisable to use one-point inner and outer shielding and two-point grounding.<\/p>\n

(3) When choosing two-point grounding, it is also necessary to consider the effect of transient current in the shielding layer to prevent it from being burned.<\/p>\n

Article 6.3.1 of GB50057-2000 "Code for Lightning Protection Design of Buildings" stipulates: ... When using shielded cables, the shielding layer should be connected to the same potential at at least two ends. When the system only requires one end to be connected to the same potential, two layers of shielding should be used, and the outer shielding layer should be processed according to the above requirements.<\/p>\n

The principle is: 1. One end of the single-layer shielding layer is grounded, there is no potential difference, and it is generally used to prevent static induction. 2. Double-layer shielding, the outermost shielding layer is grounded at both ends, and one end of the inner shielding layer is grounded at the same potential. At this time, the outer shielding layer reduces the magnetic flux and the source magnetic field strength due to the potential difference and induced current, thereby basically offsetting the induced voltage when there is no outer shielding layer.<\/p>\n

If you want to prevent electrostatic interference, you must use single-point grounding, regardless of whether it is one or two layers of shielding, because single-point grounding releases static electricity the fastest.<\/p>\n

However, except for the following two cases:<\/p>\n

1. When there is strong external current interference, single-point grounding cannot meet the fastest electrostatic discharge.<\/p>\n

If the cross-sectional area of the grounding wire is very large, single-point grounding is also required to ensure the fastest discharge of static electricity. Of course, if you really want to do that, there is no need to choose two layers of shielding.<\/p>\n

Otherwise, there must be two layers of shielding. The outer shielding is mainly to reduce the interference intensity rather than eliminate the interference. This requires multi-point grounding. Although the discharge cannot be completely discharged, it must be weakened as soon as possible. To weaken it, multi-point grounding is the best choice.<\/p>\n

For example, the cable tray in an enterprise is actually the outer shielding layer, which must be grounded at multiple points. This is the first line of defense to reduce the intensity of interference sources.<\/p>\n

The inner shield layer (in fact, people will not buy double-layer cables. Generally, the outer layer is the cable tray and the inner layer is the shield layer of the shielded cable) must be grounded at a single point, because the external strength has been reduced, and the purpose of the inner layer is to discharge as quickly as possible and eliminate interference.<\/p>\n

2. Safety requirements such as external electric shock and lightning protection.<\/p>\n

In this case, there must be two layers of protection. The outer layer is not used to eliminate interference, but for safety reasons, to ensure the safety of people and equipment, it must be grounded at multiple points. The inner layer is to prevent interference, so it must be grounded at a single point.<\/p>","protected":false},"excerpt":{"rendered":"

How to wire the shielded wire: One end of the shielded wire is grounded and the other end is suspended. When the signal line is transmitted over a long distance, due to the different grounding resistances at both ends or the current of the PEN line [\u2026]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"default","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"default","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[19],"tags":[253,236],"class_list":["post-5841","post","type-post","status-publish","format-standard","hentry","category-blog","tag-blog","tag-pingbixian"],"_links":{"self":[{"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/posts\/5841","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/comments?post=5841"}],"version-history":[{"count":0,"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/posts\/5841\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/media?parent=5841"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/categories?post=5841"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ray-tron.com\/en\/wp-json\/wp\/v2\/tags?post=5841"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}