{"id":6960,"date":"2016-08-16T09:35:15","date_gmt":"2016-08-16T07:35:15","guid":{"rendered":"https:\/\/blog.wika.com\/en\/?p=6960"},"modified":"2021-12-02T08:40:14","modified_gmt":"2021-12-02T07:40:14","slug":"what-is-meant-by-the-change-over-switching-function-with-pressure-switches","status":"publish","type":"post","link":"https:\/\/blog.wika.com\/en\/knowhow\/what-is-meant-by-the-change-over-switching-function-with-pressure-switches\/","title":{"rendered":"What is meant by the \u201cchange-over\u201d switching function with pressure switches?"},"content":{"rendered":"

A pressure switch with the \u201cchange-over\u201d switching function represents a special version of a pressure switch with two switching outputs acting oppositely to switch two circuits. A \u201cchange-over\u201d closes one circuit and simultaneously opens a second circuit. Thus a \u201cchange-over\u201d simultaneously fulfils the function of a \u201cnormally open\u201d and also a \u201cnormally closed\u201d contact. This means that, in operation, a \u201cchange-over\u201d can only ever have one connected circuit closed and one energised.<\/strong><\/p>\n

Application examples of pressure switches with \u201cchange-over\u201d switching function<\/h2>\n

\u201cChange-over\u201d contacts are used to a much lesser extent in industrial applications than the traditional \u201cnormally open\u201d and \u201cnormally closed\u201d variants. However, many applications with simple safety features can be implemented with \u201cchange-over\u201d contacts.<\/p>\n

Let’s look at simple machine monitoring, e.g. a coolant unit on a machine tool with visual fault indication (see figure). A pressure switch with a \u201cchange-over\u201d switching function monitors the coolant supply to the tool. If the supply pressure of the coolant is sufficient, then the switching circuit for a green light is made (green light \u201con\u201d). If the pump fails, however, and the supply pressure of the coolant drops off, then the switch changes its switching status. It opens the switching circuit for the green light (green light \u201coff\u201d) and simultaneously closes the switching circuit for the yellow warning light (yellow light \u201con\u201d).Thus the machine operator gets a direct visual feedback of any interruption at the coolant supply unit. Naturally, with the appropriate connection, the \u201cchange-over\u201d could switch other connected loads in place of a warning light, which could, for example, shut the machine down or sound a warning hooter.<\/p>\n

Use of mechanical versus electronic pressure switches<\/h2>\n

Through an ever-increasing level of automation, even in simple machinery, in the last years there has been a greater use of mechanical switches with \u201cnormally open\u201d and \u201cnormally closed\u201d as redundant safety monitoring for the continuous monitoring with sensors. The latest developments in modern electronic switches offer the operator, through the simultaneous provision of switching and analogue output signals, a far greater range of opportunities in the design of safety control. Thus, a control with the assistance of electronic switches can \u2212 through the analogue signal \u2212 continuously monitor system pressure, temperature or level, while also, at the same time \u2212 through the evaluation of the switch contacts \u2212 fulfilling an independent safety function through the monitoring of critical states, whereby hazards to personnel and machinery can be prevented.<\/p>\n

Apart from \u201cchange-over\u201d, manufacturers of switches offer a variety of switching functions for all applications, such as \u201cnormally closed\u201d or \u201cnormally open\u201d. With the aid of these switching functions, operators can fulfil almost 100 % of all simple control and safety tasks within machine building.<\/p>\n

Note
\n<\/strong>Further information on mechanical pressure switches<\/a><\/span> and electronic pressure switches<\/a><\/span> can be found on the WIKA website. Should you need any advice on the selection of a suitable switch, your contact <\/a>will gladly help you.<\/p>\n

Also read our article<\/strong>
\nWhat is meant by the \u201cnormally open\u201d switching function with pressure switches?<\/a><\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

A pressure switch with the \u201cchange-over\u201d switching function represents a special version of a pressure switch with two switching outputs acting oppositely to switch two circuits. A \u201cchange-over\u201d closes one circuit and simultaneously opens a second circuit. Thus a \u201cchange-over\u201d simultaneously fulfils the function of a \u201cnormally open\u201d and also a \u201cnormally closed\u201d contact. This […]<\/p>\n","protected":false},"author":11,"featured_media":6961,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[5],"tags":[79,210],"class_list":["post-6960","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-knowhow","tag-pressure-switch","tag-switching-fuction"],"acf":[],"yoast_head":"\nChange-over switching function with pressure switches<\/title>\n<meta name=\"description\" content=\"What is meant by the \u201cchange-over\u201d switching function with pressure switches? A \u201cchange-over contact\u201d closes one circuit and simultaneously opens a second.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blog.wika.com\/en\/knowhow\/what-is-meant-by-the-change-over-switching-function-with-pressure-switches\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Change-over switching function with pressure switches\" \/>\n<meta property=\"og:description\" content=\"What is meant by the \u201cchange-over\u201d switching function with pressure switches? 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