{"id":186,"date":"2013-06-26T15:51:55","date_gmt":"2013-06-26T20:51:55","guid":{"rendered":"http:\/\/blog.hilltech.com\/?p=186"},"modified":"2022-04-06T22:17:29","modified_gmt":"2022-04-07T03:17:29","slug":"reduce-the-size-of-switchgear-designs-and-increase-safety","status":"publish","type":"post","link":"https:\/\/blog.hilltech.com\/?p=186","title":{"rendered":"Reduce the size of switchgear designs and increase safety"},"content":{"rendered":"

ARLINGTON HEIGHTS, ILLINOIS, USA<\/strong>, Monday, June 24, 2013: Hill Tech Sales, a leader in Components for Electrical Power Conversion today posted information on using true Full-range fuses to reduce the\u00a0size of switchgear.<\/p>\n

In the past, Full-range fuses used an inappropriate element design where they \u201cage\u201d prematurely because they operate in the fast overcurrent range. This ageing is the changing element\u2019s characteristics because of the increased power loss during operation.<\/p>\n

Correctly designed Full-range fuses <\/a>will interrupt any value of current from short-circuit to overload interruption. They have all the characteristics of back-up fuses plus the further ability for protection in the overload range. Distribution transformer circuits should use Full-range fuses where there may not be protection on the secondary side of the transformer, and the primary fuse is needed to clear a secondary system fault.<\/p>\n

Full-Range fuse other\u00a0construction concept<\/strong><\/p>\n

\"Back-up<\/a>

Typical construction for Back-up & General Purpose fuses<\/p><\/div>\n

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Our Full-range fuses <\/a>are designed using a two zone design concept; each zone has a different element design which lowers power losses and temperature rise leading to reliable operation in the overload range.<\/p>\n

Full-Range fuse NEW concept<\/strong><\/p>\n

\"A<\/a>

Other Full-range fuse do not use a dual zone construction<\/p><\/div>\n

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New design concept for Full-range fuses:<\/strong>
\nTwo Zone concept, back-up zone, overload zone (Thermal Zone)
\nSpecial melting element material for parallel melting element design<\/p>\n

Back-up zone<\/strong>
\nBack-up zone consists of upto 15 individual silver melting elements wound onto a star-shaped carrier imbedded in quartz sand.<\/p>\n

Overload zone (Thermal Zone)<\/strong>
\nThe elements in this zone are notched, which reduces the element cross section generating power loss and\u00a0creating heat. In order to minimize the effects of this heat, two things are done. First, the heat is confined to a thermal separated from other parts of the fuse by a thermal barrier. Secondly, the melting elements are made of a special alloy differentiating it from silver (melting point 960\u00b0C) which is typically used.<\/p>\n

\"Note<\/a>

Full-range fuse dual zone method<\/p><\/div>\n

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Melting element materials has three important properties:<\/strong><\/p>\n

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  1. Low melting point ~ 600\u00b0C.<\/li>\n
  2. Enhanced heat absorption by the decay of metal-oxide components in the arcing process. Metal oxides are created by internal oxidation of the alloy just before reaching the melting temperature.<\/li>\n
  3. Increased recovery voltage. The AC voltage arc is immediately absorbed after current zero making re-ignition very high. These fault arcs are extinguished much faster when made of this alloy as compared to elements of pure silver.<\/li>\n<\/ol>\n

    The two zones are placed in series for good short-circuit and overload protection.<\/p>\n

    Full-range fuses protect like two fuses, Back-up & General-Purpose<\/strong>.<\/p>\n

    \"Why<\/a>

    Why Full-Range fuse is better than Back-up or GP<\/p><\/div>\n

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    <\/strong>\u00a0Full-range fuses protect the transformer by:<\/strong><\/p>\n

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    1. Meeting transformer inrush current points.<\/li>\n
    2. Have a rated current sufficiently above the transformer rated current in order to allow for admissible overloads.<\/li>\n
    3. Provide best possible protection during overload caused by winding short circuits.<\/li>\n
    4. Discriminative currents over the complete interrupting range.<\/li>\n<\/ol>\n

      Increasing Switchgear safety<\/strong><\/p>\n

      Switchgear safety can be increased by using Full-range fuses on the high voltage side of the transformer because other methods only protect against:<\/p>\n