Text version of the page

Transformer TerminalRET 541, RET 543, RET 545

1MRS755543

Table 7: Protection function blocks

Three-phase non-directional overcurrent protection, low-set stages, NOC3Low, 3I>, NOC3LowB,3I> Start current 0.10 5.00 x In Operate time at DT mode 0.05 300.00 s Time multiplier at IDMT mode 0.05 1.00 Operation mode ! Not in use ! Definite time ! ! Extremely inverse ! ! Very inverse ! ! Normal inverse ! ! Long time inverse ! ! RI-type inverse ! ! RD-type inverse ! IEEE curves Measuring mode ! Peak-to-peak ! Fundamental frequency Drop-off time of the operate time counter 0...1000 ms Note! The values below apply when f/fn = 0.95...1.05 Operation accuracy –2.5% of set value or –0.01 x In Start time: ! ! - Injected currents >2.0 x start current: - internal time ! <32 ms - total time <40 ms Reset time 40...1000 ms (depends on the minimum pulse width set for the trip output) Reset ratio, typically 0.95 Retardation time >, and instantaneous stage, NOC3Inst, 3I>>> Start current 0.10 40.00 x In Operate time 0.05 300.00 s Operation mode ! Not in use ! ! Definite time ! ! Instantaneous ! Measuring mode ! Peak-to-peak ! Fundamental frequency Drop-off time of the operate time counter 0...1000 ms Note! The values below apply when f/fn = 0.95...1.05 Operation accuracy 0.1...10 x In: –2.5% of set value or –0.01 x In 10...40 x In: –5.0% of set value Start time: ! ! - injected currents >2.0 x start current: - internal time <32 ms - total time <40 ms Reset time ! 40...1000 ms (depends on the minimum pulse width set for the trip output) Reset ratio, typically 0.95 Retardation time
19