A Short Circuit analysis is used to determine the magnitude of short circuit current the
system is capable of producing and compares that magnitude with the interrupting rating
of the overcurrent protective devices (OCPD). Since the interrupting ratings are based by
the standards, the methods used in conducting a short circuit analysis must conform to the
procedures which the standard making organizations specify for this purpose. In the
United States, the America National Standards Institute (ANSI) publishes both the
standards for equipment and the application guides, which describes the calculation
methods.
Short circuit currents impose the most serious general hazard to power distribution
system components and are the prime concerns in developing and applying protection
systems. Fortunately, short circuit currents are relatively easy to calculate. The
application of three or four fundamental concepts of circuit analysis will derive the basic
nature of short circuit currents. These concepts will be stated and utilized in a step-bystep
development.
The three phase bolted short circuit currents are the basic reference quantities in a system
study. In all cases, knowledge of the three phase bolted fault value is wanted and needs
to be singled out for independent treatment. This will set the pattern to be used in other
cases.
A device that interrupts short circuit current, is a device connected into an electric circuit
to provide protection against excessive damage when a short circuit occurs. It provides
this protection by automatically interrupting the large value of current flow, so the device
should be rated to interrupt and stop the flow of fault current without damage to the
overcurrent protection device. The OCPD will also provide automatic interruption of
overload currents.
A Short Circuit analysis is used to determine the magnitude of short circuit current thesystem is capable of producing and compares that magnitude with the interrupting ratingof the overcurrent protective devices (OCPD). Since the interrupting ratings are based bythe standards, the methods used in conducting a short circuit analysis must conform to theprocedures which the standard making organizations specify for this purpose. In theUnited States, the America National Standards Institute (ANSI) publishes both thestandards for equipment and the application guides, which describes the calculationmethods.Short circuit currents impose the most serious general hazard to power distributionsystem components and are the prime concerns in developing and applying protectionsystems. Fortunately, short circuit currents are relatively easy to calculate. Theapplication of three or four fundamental concepts of circuit analysis will derive the basicnature of short circuit currents. These concepts will be stated and utilized in a step-bystepdevelopment.The three phase bolted short circuit currents are the basic reference quantities in a systemstudy. In all cases, knowledge of the three phase bolted fault value is wanted and needsto be singled out for independent treatment. This will set the pattern to be used in othercases.A device that interrupts short circuit current, is a device connected into an electric circuitเพื่อป้องกันความเสียหายมากเกินไปเมื่อเกิดลัดวงจร มีการป้องกันนี้ โดยอัตโนมัติรบกวนค่าขนาดใหญ่กระแสปัจจุบัน ดังนั้นอุปกรณ์ควรจัดการขัดจังหวะ และหยุดการไหลของข้อบกพร่องที่ปัจจุบันไม่ มีความเสียหายอุปกรณ์ป้องกัน overcurrent OCPD จะให้ขัดจังหวะอัตโนมัติโอเวอร์โหลดกระแส
การแปล กรุณารอสักครู่..