Safety barriers and interlocks full is supplied with

This preview shows page 20 - 22 out of 51 pages.

Safety barriers and interlocks – Full compartmentalization is supplied with primary functions separated by grounded metal barriers. All bussing is insulated and live parts are not exposed. Safety interlocks work with the breaker racking system. These protective features provide safety for operating personnel. Breakers can withstand various levels of commissioning which involves many switching operations. Hospital Applications Main service switchgear Paralleling switchgear Ratings 4.76 kV – 15 kV (to 13.8 kV nominal) 1200 A – 3000 A 250 MVA – 1000 MVA interrupting capacity 60 kV and 95 kV BIL Indoor and outdoor enclosures Standard Features (as defined by ANSI C37.20.2) Removable (drawout) circuit breaker Fully compartmented construction Grounded metal barriers enclose all live parts Automatic shutters Insulated bus Mechanical interlocks Disconnect type voltage transformers – CPT and VTs Grounded breaker truck in and between test/disconnected and connected positions Low voltage instrument/control compartment isolated from primary voltage areas
Image of page 20

Subscribe to view the full document.

19 Arc Terminator Medium voltage switchgear can have an additional degree of protection from damaging open arcing faults with the Arc terminator arc extinguishing system. This system detects and controls the effects of arcing faults. It extinguishes arcs rapidly, significantly minimizing equipment damage and reducing equipment downtime. Benefits Confines the effects of the arc to the point of initiation Enhances protection by detecting and commuting arc fault current Extinguishes high magnitude arc currents within less than 1 / 4 of a cycle and prevents the buildup of high internal pressures Features Uses sensors to detect arcs in medium voltage switchgear Initiates the closing of a high-speed vacuum switch if an arc is detected via the electronic control unit Uses two sensing inputs: Optical sensors detect arcing faults Current transformers are used to detect any change in current (both input events must occur together to operate the high-speed switch) The Arc Terminator system can be shipped with any new switchgear lineup Easy to install and operate: no settings or other calculations required during switchgear installation Switchgear protective relaying functions are coordinated to provide maximum protection with the addition of the Arc Terminator system How it works The Arc Terminator system confines the effects of an arcing fault to the point of initiation. When an arc is detected, a high speed vacuum switch closes, effectively crow-baring the short circuit. This action creates a solid conducting path for the current parallel with the arc. The open burning arc is extinguished, preventing the buildup of damaging pressures. The energy released by the arcing fault is significantly reduced. The electronic control requires two sensing inputs: (1) optical sensors to detect arcing faults and (2) current sensors to detect changes in the current waveform.
Image of page 21
Image of page 22

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern