Nova Patents
EP0740320A2

Apparatus for gas circuit breaker with reactor and capacitor connected in series and method for setting its circuit parameter

Abstract

A small-sized arrangement for a circuit breaker includes at least one DC circuit breaker (1a, 1b, ..., 1k), a parallel impedance means with a suitably determined inductance (L) and a suitable capacitance (C), and an energy-absorbing element (4). The parallel impedance means has a parallel reactor (3) of a carefully selected inductance and a parallel capacitor (2) of a smaller capacitance value. Determining the reactance and capacitance values of the parallel reactor (2) and parallel capacitor (3) to satisfy certain conditions can cause the DC circuit breaker (1a, 1b, ..., 1k) to take full advantage of the inherent performance. The interruption time remains minimal, thereby achieving enhanced interruption performance. Since the capacitance (C) of parallel capacitor (3) is rendered relatively smaller, the device can be small in size and low in cost.

EP0740320A2, drawing sheet 1
Sheet 1 of 54

Term

Term ended

Projected expiry passed 26 April 2016, 10.4 years ago.

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3 claims: 3 independent, 0 dependent

  1. 1
    An arrangement for a gas circuit breaker comprising a DC circuit breaker (1) for controlling the flow of DC current (i o ) in a power system, a parallel impedance means connected in parallel with the DC circuit breaker (1) and comprising a parallel capacitor (3) and a parallel reactor (2), and an energy-absorbing element (4) for said parallel capacitor (3), characterized in that said parallel reactor (2) has an inductance L (measured in µH) determined to satisfy 1.93 x 10 3 I c   5 i o   0.5 ≦ L ≦ 5.17 x 10 3 I c   5 i o   0.5 where "i o " is an interruption current value of the DC current (measured in amperes), and "I c " is a critical normalized interruption current of said DC circuit breaker, wherein the normalized interruption current I o is defined as I o = i o nC/θ where "n" is an energy loss of arc generated when the DC current is cut off, "C" is the capacitance of the parallel capacitor (3), and "θ" is the time constant of arc.
  2. 2
    An arrangement for a gas circuit breaker comprising a plurality of series-connected DC circuit breakers (1a, 1b, ..., 1k) of substantially the same capacity for controlling the flow of DC current (i o ) in a power system, a parallel impedance means connected in Parallel with said DC circuit breakers (1a, 1b, ..., 1k) and comprising a parallel capacitor (3) and a parallel reactor (2), and an energy-absorbing element (4) for said parallel capacitor (3), characterized in that said parallel reactor (2) has an inductance L (measured in µH) determined to satisfy 1.93 x 10 3 I c   5 i o   0.5 ≦ L ≦ 5.17 x 10 3 I c   5 i o   0.5 where "i o " is the interruption current value of the DC current (measured in amperes), "I c " is the critical normalized interruption current of the DC circuit breaker, said parallel capacitor (3) has a capacitance C (µF) determined to satisfy 2.44×10 -4 k · i o ​ 1.5 I c ​ 3 ≦ C ≦ 6.53×10 -4 k · i o ​ 1.5 I c ​ 3 , wherein the normalized interruption current I o is defined as i o kn s C/θ where "k" is the number of said DC circuit breakers (1a, 1b, ..., 1k), "n s " is the energy loss of arc generated when the DC current is interrupted in one of said circuit breakers, and "θ" is the time constant of arc.
  3. 3
    A reactance setting method for use in an arrangement for a gas circuit breaker comprising a DC circuit breaker (1, 1a, 1b, ..., 1k) for controlling the flow of DC current (i o ) in a power system, a parallel impedance means connected in parallel with the DC circuit breaker (1; 1a, 1b, ..., 1k) and comprising a parallel capacitor (3) and a parallel reactor (2), and an energy-absorbing element (4) for said parallel capacitor (3), said method comprising the step of:determining the parallel capacitor capacitance C (µF) and the parallel reactor inductance L (µF) by the following relations: 2.2 ≦ k 1 ( L C ) 0.5 ≦ 3.6 , 2.2 ≦ k 2 ( 1 LC ) 0.5 ≦ 3.6 , where k 1 = (i o /1000) I c ​ 4 , k 2 = (i o /1000) 0.5 I c 10 4 , wherein the normalized interruption current I o is defined as i o nC/θ where "i o " is the interruption current value of the DC current (measured in amperes), "n" is the energy loss of arc generated when the DC current is interrupted, "C" is the capacitance of the parallel capacitor, and "θ" is the time constant of arc.
Independent claims3