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-   -   Theory of vacuum Circuit Breaker & sf6 circuit breaker (https://www.askmehelpdesk.com/showthread.php?t=105047)

  • Jun 28, 2007, 07:30 AM
    prashantkolhe
    Theory of vacuum Circuit Breaker & sf6 circuit breaker
    I want to know about the basic Theory of vacuum Circuit Breaker & sf6 circuit breaker
  • Apr 22, 2008, 06:55 PM
    alectrician
    First off, sf6 stands for sodium hexafloride gas which is inert, Siemens did some stuff in a 500kv switchyard I worked in and with a SF6 breaker the air gap is about 6 inches and the switch size is measured in inches, compared to the "old" air breakers that are huge (larger than your garage) and sounded like a cannon going off when they opened. With SF6 your switchyards and main disconnects can be very unobtrusive at a time when substations are NIMBY. My experience with them was fine although much closer tolerances are required(mm not inches)
  • Mar 24, 2009, 12:12 PM
    schaefer101
    Sulphur hexafluoride (SF6) is an inert, heavy gas having good dielectric and arc extinguishing properties. The dielectric strength of the gas increases with pressure and is more than of dielectric strength of oil at 3 kg/cm2. SF6 is now being widely used in electrical equipment like high voltage metal enclosed cables; high voltage metal clad switchgear, capacitors, circuit breakers, current transformers, bushings, etc. The gas is liquefied at certain low temperature, liquefaction temperature increases with pressure.
    Sulphur hexafluoride gas is prepared by burning coarsely crushed roll sulphur in the fluorine gas, in a steel box, provided with staggered horizontal shelves, each bearing about 4 kg of sulphur. The steel box is made gas tight. The gas thus obtained contains other fluorides such as S2F10, SF4 and must be purified further SF6 gas generally supplier by chemical firms. The cost of gas is low if manufactured in large scale.

    The previous answer was inept.

    Medium-voltage circuit breakers rated between 1 and 72 kV may be assembled into metal-enclosed switchgear line ups for indoor use, or may be individual components installed outdoors in a substation. Air-break circuit breakers replaced oil-filled units for indoor applications, but are now themselves being replaced by vacuum circuit breakers (up to about 35 kV). Like the high voltage circuit breakers described below, these are also operated by current sensing protective relays operated through current transformers. The characteristics of MV breakers are given by international standards such as IEC 62271. Medium-voltage circuit breakers nearly always use separate current sensors and protection relays, instead of relying on built-in thermal or magnetic overcurrent sensors.

    Medium-voltage circuit breakers can be classified by the medium used to extinguish the arc:

    Vacuum circuit breaker—With rated current up to 3000 A, these breakers interrupt the current by creating and extinguishing the arc in a vacuum container. These are generally applied for voltages up to about 35,000 V, [4] which corresponds roughly to the medium-voltage range of power systems. Vacuum circuit breakers tend to have longer life expectancies between overhaul than do air circuit breakers.
    Air circuit breaker—Rated current up to 10,000 A. Trip characteristics are often fully adjustable including configurable trip thresholds and delays. Usually electronically controlled, though some models are microprocessor controlled via an integral electronic trip unit. Often used for main power distribution in large industrial plant, where the breakers are arranged in draw-out enclosures for ease of maintenance.
    SF6 circuit breakers extinguish the arc in a chamber filled with sulfur heaxafluoride gas.
    Medium-voltage circuit breakers may be connected into the circuit by bolted connections to bus bars or wires, especially in outdoor switchyards. Medium-voltage circuit breakers in switchgear line-ups are often built with draw-out construction, allowing the breaker to be removed without disturbing the power circuit connections, using a motor-operated or hand-cranked mechanism to separate the breaker from its enclosure.
  • Jul 8, 2009, 01:48 PM
    Michael Garces
    Quote:

    Originally Posted by alectrician View Post
    first off, sf6 stands for sodium hexafloride gas which is inert, Siemens did some stuff in a 500kv switchyard I worked in and with a SF6 breaker the air gap is about 6 inches and the switch size is measured in inches, compared to the "old" air breakers that are huge (larger than your garage) and sounded like a cannon going off when they opened. With SF6 your switchyards and main disconnects can be very unobtrusive at a time when substations are NIMBY. My experience with them was fine although much closer tolerances are required(mm not inches)

    What is really SF6 stands for?it is sodium hexaflouride or sulfur hexaflouride?
  • Aug 6, 2009, 06:09 PM
    reignoffire
    SF6 stands for sulphur hexafluoride...
  • Aug 29, 2009, 01:44 PM
    sivani
    Quote:

    Originally Posted by prashantkolhe View Post
    I want to know about the basic Theory of vacuum Circuit Breaker & sf6 circuit breaker

    & construction &display the every parts with photograph
  • Aug 29, 2009, 01:47 PM
    sivani
    Quote:

    Originally Posted by prashantkolhe View Post
    I want to know about the basic Theory of vacuum Circuit Breaker & sf6 circuit breaker

    display the every parts with photograph
  • Oct 8, 2009, 05:51 AM
    nivaldosilveira
    Hy srs,

    I would like to know if you know some suppliers os Eletric Panels in SF6 for 36kV.

    I want to buy a lot of and I need to quote urgently.

    Thanks

    Nivaldo

    [email protected]
  • Oct 21, 2009, 11:40 PM
    surag1982
    Nivaldosilveira, please. Send your contact details to email: [email protected]
  • Feb 1, 2011, 04:19 AM
    rumon
    What sf6 switchgear
  • Oct 17, 2011, 06:55 AM
    vlnmurthy
    Sf6 stands for sodium hexafloride gas which is inert.it is control in arc
  • Oct 24, 2011, 10:55 AM
    dbdtbiswas

    Here vacuum process is used for arc quenching property..
  • Feb 14, 2012, 06:14 AM
    akbarian
    Please inform me about comparison of sf6 and vacuum regarding to prices ( one brand)
  • Jul 10, 2012, 07:19 AM
    ETUK
    What is the cost of SF6 breaker
  • Jul 10, 2012, 07:26 AM
    ETUK
    Where can I buy 15MVA 33kv SF6 breakers
  • Dec 25, 2012, 10:22 AM
    hspatel1312
    Circuit breaker is very simple and also it's operation. Here is a best article for operation of vacuum circuit breaker and advantages and working. Check it out. This may help you.

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