{"id":1221,"date":"2020-07-06T19:44:59","date_gmt":"2020-07-06T19:44:59","guid":{"rendered":"https:\/\/www.zillionsbuyer.com\/blog\/?p=1221"},"modified":"2020-07-08T06:09:53","modified_gmt":"2020-07-08T06:09:53","slug":"explain-vch-giving-construction-principle-working-and-application","status":"publish","type":"post","link":"https:\/\/www.zillionsbuyer.com\/blog\/explain-vch-giving-construction-principle-working-and-application\/","title":{"rendered":"What VCR giving construction, working & application"},"content":{"rendered":"\n

Vacuum Circuit Breaker (VCR):<\/a><\/strong><\/p>\n\n\n\n

when contacts of a breaker are opened in\nvacuum, the interruption occurs at first current-zero with dielectric strength\nbetween the contacts, building up at a rate thousands of times higher than that\nobtained with other circuit breakers<\/p>\n\n\n\n

Principle\n<\/strong>:<\/p>\n\n\n\n

The production of arc in a vacuum circuit\nbreaker and its extinction can be explained as follows:<\/p>\n\n\n\n

When the contacts of the breaker are opened\nin vacuum (10-7<\/sup> to 10–<\/sup>5 torr), an arc is produced between\nthe contacts by the ionization of metal vapours of contacts. However, the arc\nis quickly extinguished because the metallic vapours electrons and ions\nproduced during are rapidly condense on the surface of the breaker contacts,\nresulting in quick recovery of dielectric strength.<\/p>\n\n\n\n

We should consider the feature of vacuum as\nan arc quenching medium. As soon as the arc is produced in vacuum, it is\nquickly extinguished due to the fast rate of recovery of dielectric strength in\nvacuum.<\/p>\n\n\n\n

The parts of a typical vacuum circuit\nbreaker. It consists of fixed contact, moving contact and are shield mounted\ninside a vacuum chamber. The movable member is connected to the control\nmechanism by stainless steel bellows.<\/p>\n\n\n\n

This enables the permanent scaling of the\nvacuum chamber so as to eliminate the possibility of leak. A glass vessel or\nceramic vessel is used as the outer insulating body. The arc shield prevents\nthe deterioration of the internal dielectric strength by preventing metallic\nvapours on the inside surface of the outer insulating cover.<\/p>\n\n\n\n

Working\n:<\/strong><\/p>\n\n\n\n

When the breaker operates, the moving\ncontact separates from thefixed\ncontact and an arc is struck between the contacts. The production of arc is due\nto the ionization of metal ions and depends very much upon the material of\ncontacts.<\/p>\n\n\n\n

The arc is quickly extinguished because the\nmetallic vapours, electrons and ions produced during are are diffused in a\nshort time and seized by the surfaces of moving and fixed-members and shields.<\/p>\n\n\n\n

Since vacuum has very fast rate of recovery\nof dielectric strength the arc extinction in vacuum breaker occurs with a short\ncontact separation (say 0.625 cm.)<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Advantages\n:<\/strong><\/p>\n\n\n\n

1.They are compact, reliable and have\nlonger life.<\/p>\n\n\n\n

2.There are no fire hazards.<\/p>\n\n\n\n

3.There is no generation of gas during and\nafter operation.<\/p>\n\n\n\n

4.They can interrupt any fault current. The\noutstanding feature of a VCB is that<\/p>\n\n\n\n

5.it can break any heavy fault current\nperfectly just before the contacts reach the definite open position<\/p>\n\n\n\n

6.They require little maintenance and are\nquite in operation.<\/p>\n\n\n\n

7.They can successfully withstand lightning\nsurge,<\/p>\n\n\n\n

8.They have low arc energy.<\/p>\n\n\n\n

9.They have low inertia and hence require\nsmaller power for control mechanism<\/p>\n\n\n\n

Applications\n:<\/strong> For a country like India, where distances are\nquite large and accessibility to remote areas difficult, the installation of such\noutdoor, maintenance-free circuit breakers should prove a definite advantage,\nVacuum circuit breakers are being employed for outdoor applications ranging\nfrom 22 kV to 66 kV. Even with limited rating of say 60 to 100 MVA, they are\nsuitable for a majority of applications in rural areas.<\/p>\n","protected":false},"excerpt":{"rendered":"

Vacuum Circuit Breaker (VCR): when contacts of a breaker are opened in vacuum, the interruption occurs at first current-zero with dielectric strength between the contacts, building up at a rate thousands of times higher than that obtained with other circuit breakers Principle : The production of arc in a vacuum circuit breaker and its extinction […]<\/p>\n","protected":false},"author":1,"featured_media":1222,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[44],"tags":[],"class_list":["post-1221","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-electrical-engineering"],"_links":{"self":[{"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/posts\/1221","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/comments?post=1221"}],"version-history":[{"count":2,"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/posts\/1221\/revisions"}],"predecessor-version":[{"id":1231,"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/posts\/1221\/revisions\/1231"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/media\/1222"}],"wp:attachment":[{"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/media?parent=1221"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/categories?post=1221"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.zillionsbuyer.com\/blog\/wp-json\/wp\/v2\/tags?post=1221"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}