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Some technical characteristic of current-limiting reactors. Airtype - reactor linear magnetic behaviour (L - constant) spreading magnetic field around reactor (weak EMC behaviour) damping of reactor noise is difficult space consuming earth-quake withstand capability expensive
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Some technical characteristic of current-limiting reactors • Airtype - reactor • linear magnetic behaviour (L - constant) • spreading magnetic field around reactor (weak EMC behaviour) • damping of reactor noise is difficult • space consuming • earth-quake withstand capability expensive Oiltype – reactor • nonlinear magnetic behaviour for high currents (L – decreasing at high currents) • almost no electromagnetical radiation outside tank • antinoise damping can easily be provided by enclosure or by tank wall damping • cooling equipment (radiator bank) free placeable
Design of oil-type current-limiting reactors • limb as gapped core limb without iron core • Fe-mass > • Cu-mass < • total mass > • three limb five limb • height > • Z0 / Z1 ~ 0.8 < 1 • core induction: - low for short-circuit limiting • - normal for power flow controlling (post-failure application)
Initial issues to be discussed • application • comparison between oil-type and dry-type - noise request - EMC - space available - impedance (L-I-curve, symmetry between phases) - earth-quake conditions • range of magnetic linearity -> impedance at normal and at short-circuit cond. • zero-sequence impedance • available current level for heat-run test • …
Example: 3~ series reactor for NGCT „Elstree DR2“ • application: post-failure load-flow control • cooling: ODAF • throuput power: 2000 MVAR • reactor power: 400 MVAR • nominal current: 2887 A, system voltage: 400 kV • induction: 1,3 T @ 2887 A • current density: 3,6 A/mm^2
Example: 3~ series reactor for ConEdison in New York • application: short-circuit current limitation and load-flow control • cooling: ONAN • throuput power: 358 MVAR • reactor power: 64 MVAR • nominal current: 1500 A / 2800A / 7500 A, system voltage: 138 kV • induction: 0,37 T @ 1500 A • current density: 2,3 (4,3) A/mm^2