L_V_Circuit_Breakers - Federal Elektrik - #2

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Untitled table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:2.20pt "Arial", sans-serif; } .font1 { font:6.00pt "Arial", sans-serif; } .font2 { font:8.00pt "Arial", sans-serif; } .font3 { font:13.00pt "Arial", sans-serif; } .font4 { font:16.00pt "Arial", sans-serif; } .font5 { font:29.00pt "Arial", sans-serif; } LV. CIRCUIT BREAKERS Network Sequenti.il Connection: Sequential connection is a utilization type which allows use ot lower-cosi circurt breakers at Ihe load side by using the current limiting feature ol circuit breakers Compact circuit b'eakers at the network side provide protection against over load and short circuit currents Thèse éléments allow circuit breakers with a breaking capabiiity lower than the short circuit current to operate wiihin rated breaking capabiiity limit As the current is kept under control of the limiter circuit breaker in the whole circuit, sequential connection is usaful for ail Ihe switching devices at load side of the circuit breaker Utilizalion of Sequential Connection: In sequential connections, circuit breaker éléments can bo placed In différent panels. In this way, sequential connection makes il possible to use circuit Dreakers with lower capacily than the possible les operating short circuit current to occur in the area of the devtce. Important point is that a circuit breaker at Ihe capacity to break this short circuit current shouid be connected at the network side Coordination Among Circuit Breakers: Utilizalion of a circuit breaker. which has a breaking capacity lower than the short circuit current, is atlowed only when another circuit oreaker with the required breaking capacity is placed ai the network side. In this case, characteristics ot both éléments shouid be coordinated wilh each other in a way not to give any damage to the élément at the load side and cables protected by thèse éléments, 3-Step Sequenlial Connection; Crtteria about sequential connection of serially connected A, B and C circuit breakers are futfiilea in two conditions. A breaker placed at the network side is used for both B and C breakers for sequential connection. Mere, u shouid be checked whether (A+B and A+C} and (A+B and B+C) combinaisons have Ihe required breaking capacity or nol. (Figure - 18) F53 25CW lcs=70 kA ***** Flg-18 .o.nl Sequential Connection Table Network Side FïO F11 F21 F6I F12 F22 F31 F51 F62 F71 F32 F52 F82 F91 F10I F111 F92!FÏw!fÏ12 F33 F53 F83 kA F10 F11 16 25 FBI ~FÎ2~ 30 F22 " F31 F51 35 F62 F71 F32 F52 50 F82 F33 F53 70 F83 25 25 25 20 25 25 30 30 30 30 30 3fi 35 35 35 35 35 35 25 3ûj 35 35r 35 35 35 35; 35 - ' 35 50 65 70 45 25 70 70 70 70 20 70 70 70 70 70 70 70 70 70 70 70 70 70 20 35 35 45 25 20 50 50 50 50 ' 50 35 '35 '3535 35 - 50 50 35 50 35 50 50 50 50 50 50 50 50 50 50 60 50 50 50 50 50 50 50 50 70 70 70 70 70 70 70 70 50 50 50 65 65 65 50 60 50 65 65 65 50 50 50 65 65 65 70 70 70 70 <?FEDERAL 1/18