EP0123889A1 - Direct current circuit breaker - Google Patents
Direct current circuit breaker Download PDFInfo
- Publication number
- EP0123889A1 EP0123889A1 EP84103251A EP84103251A EP0123889A1 EP 0123889 A1 EP0123889 A1 EP 0123889A1 EP 84103251 A EP84103251 A EP 84103251A EP 84103251 A EP84103251 A EP 84103251A EP 0123889 A1 EP0123889 A1 EP 0123889A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- current
- circuit breaker
- arc
- gas
- nitrogen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
- H01H33/02—Details
- H01H33/04—Means for extinguishing or preventing arc between current-carrying parts
- H01H33/22—Selection of fluids for arc-extinguishing
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
- H01H33/02—Details
- H01H33/59—Circuit arrangements not adapted to a particular application of the switch and not otherwise provided for, e.g. for ensuring operation of the switch at a predetermined point in the ac cycle
- H01H33/596—Circuit arrangements not adapted to a particular application of the switch and not otherwise provided for, e.g. for ensuring operation of the switch at a predetermined point in the ac cycle for interrupting dc
Definitions
- This invention relates to a direct current circuit breaker and, more particularly, to a direct current circuit breaker in which the current is commutated by its own action at the time of current interruption and in which unstable arc characteristics are utilized for establishing current zero point or zero crossing for breaking the circuit.
- a direct current source 1 indicated conveniently as a voltage source is connected to a resistance 2 and an inductance 3 proper to the transmission line for providing a direct current system.
- a current breaker unit 4 comprised of a current breaker section 5 adapted for breaking the circuit, a capacitor 6 and a surge absorber 7 formed by metal oxide resistor.
- the capacitor 6 is connected in parallel with the section 5 and used for current commutation.
- the arc produced in the circuit shown in Fig. 1 and having the characeristics represented by the formula (1) becomes unstable on the condition that where ⁇ represents a thermal time constant of the arc, "C”a capacitance of the capacitor 6, "T”a d.c. current and”e s "a steady-state arc voltage, with a being as defined in the equation (1).
- ⁇ represents a thermal time constant of the arc
- C a capacitance of the capacitor 6
- T a d.c. current and”e s "a steady-state arc voltage
- e a represents the voltage across the terminals of the breaker section 5, I the d.c. current, i the current flowing into the breaker section 5 and i the unstable oscillating current flowing from capacitor 6 into the arc.
- the current can be interrupted at the zero crossing points.
- the term of the d.c. current I that can be interrupted can also be selected to a larger value for thereby improving the current braking capacity of the current breaker unit.
- a gas mixture consisting essentially of the SF 6 -gas and air or nitrogen is used and blown into the arc as an arc-extinguishing and insulating medium for the gas blowing type d.c. circuit breaker.
- Fig. 3 shows a preferred embodiment of the present invention wherein the same numerals 1 through 7 as those used in Fig. 1 are used to depict the same or corresponding parts.
- the d.c. breaker unit 4 is comprised of a fixed contact 8, a movable contact 9 that may be engaged with or disengaged from this fixed contact, a flow guide member 10 placed around these contacts and secured to said movable contact, a cylinder 11 secured to said flow guide member and operable with said movable contact, a buffer chamber 13 defined between the cylinder and a piston 12 slidable therein, a commutating capacitor 6 in parallel with said fixed and movable contacts, and a surge absorber 7.
- a higher value of a can be obtained by using a gas mixture consisting essentially of SF 6 and nitrogen or air as an arc blowing medium than in the case of using a gas consisting solely of SF 6 .
- the marginal or critical temperature at which the above gas mixture is converted into the liquid phase is elevated than in the case of the SF 6 -gas.
- the mixture ratio of nitrogen or air to the SF 6 -gas may preferably be in the range of 20 to 80 vol. percent of nitrogen or air to the SF 6 -gas.
- the lower limit of 20 vol. percent is set because an increase in the value of a or arc voltage may not be increased for lower nitrogen or air contents while the upper limit of 80 vol. percent is set because the buffer operation ceases to be effective for higher nitrogen or air contents.
- the arrangement of the present invention provides a d.c. circuit breaker having a larger current breaking capacity through the use of the gas mixture consisting essentially of SF 6 gas and air or nitrogen as the arc-extinguishing and insulating medium.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Circuit Breakers (AREA)
- Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)
Abstract
Description
- This invention relates to a direct current circuit breaker and, more particularly, to a direct current circuit breaker in which the current is commutated by its own action at the time of current interruption and in which unstable arc characteristics are utilized for establishing current zero point or zero crossing for breaking the circuit.
- The piror-art construction of the current breaker of the above described type is shown in the wiring circuit of Fig. 1, wherein a direct
current source 1 indicated conveniently as a voltage source is connected to aresistance 2 and aninductance 3 proper to the transmission line for providing a direct current system. To this system is connected acurrent breaker unit 4 comprised of a current breaker section 5 adapted for breaking the circuit, acapacitor 6 and a surge absorber 7 formed by metal oxide resistor. Thecapacitor 6 is connected in parallel with the section 5 and used for current commutation. - With the direct current"I"flowing through the current breaker section 5 of the
unit 4 when the section 5 starts its circuit breaking operation, that is, its contacts start to be separated from each other, an arc is generated between the contacts of the section 5 and the direct current then flows through the arc. - It is well-known that, for a certain current range, the relation between the steady-state arc voltage e and the steady-state arc current is through a variety of gases may be approximated by the following formula:
- On the other hand, the arc produced in the circuit shown in Fig. 1 and having the characeristics represented by the formula (1) becomes unstable on the condition that
capacitor 6, "T"a d.c. current and"es"a steady-state arc voltage, with a being as defined in the equation (1). When the condition given by the equation (2) is satisfied, the arc produced in the circuit breaker section 5 becomes unstable. - The voltage/current characteristics prevailing at this time are shown in Fig. 2. In this figure, ea represents the voltage across the terminals of the breaker section 5, I the d.c. current, i the current flowing into the breaker section 5 and i the unstable oscillating current flowing from
capacitor 6 into the arc. - Since the above described oscillating current has current zero points, the current can be interrupted at the zero crossing points. In other words, it is possible to interrupt the d.c. current when the condition of the equation (2) is satisfied. By selecting the right side term of the equation (2) to a larger value, the term of the d.c. current I that can be interrupted can also be selected to a larger value for thereby improving the current braking capacity of the current breaker unit.
- In the SF6-gas blowing type conventional d.c. current breaker, it is the conventional practice to increase the force of gas blowing or make use of a construction of an arc- extinguishing chamber designed for extending the arc length. However, since the SF6-gas tends to be liquefied under an elevated pressure, a certain limitation is placed on increasing the gas pressure for producing a strong gas blowing force. On the other hand, the overall device tends to be complicated by the provision of the arc-extinguishing chamber.
- In view of the foregoing, it is a principal object of the present invention to obviate the above described deficiency of the SF6-gas blowing type d.c. circuit breaker and to provide a d.c. circuit breaker having a higher current breaking capacity. According to the present invention, a gas mixture consisting essentially of the SF6-gas and air or nitrogen is used and blown into the arc as an arc-extinguishing and insulating medium for the gas blowing type d.c. circuit breaker.
- One way of carrying out the invention is described in detail below with reference to drawings, in which
- Fig. 1 is a diagrammatic view showing the construction of the conventional circuit breaker of the type in which the current is commutated spontaneously at the time of current interruption,
- Fig. 2 is a chart showing the voltage and current characteristics with time in the circuit breaker shown in Fig. 1, and
- Fig. 3 is a diagrammatic view showing the construction of the current breaker according to an embodiment of the present invention.
- With respect to the description of the Figures 1 and 2 it is referred to the above introduction.
- Fig. 3 shows a preferred embodiment of the present invention wherein the
same numerals 1 through 7 as those used in Fig. 1 are used to depict the same or corresponding parts. The d.c.breaker unit 4 is comprised of a fixedcontact 8, a movable contact 9 that may be engaged with or disengaged from this fixed contact, aflow guide member 10 placed around these contacts and secured to said movable contact, a cylinder 11 secured to said flow guide member and operable with said movable contact, abuffer chamber 13 defined between the cylinder and apiston 12 slidable therein, a commutatingcapacitor 6 in parallel with said fixed and movable contacts, and a surge absorber 7. - In the operation of the d.c.
circuit breaker unit 4, when the movable contact 9 is contacted with thefixed contact 8, theunit 4 being thus closed, the totality of the current supplied from the d.c. system flows through thesecontacts 8, 9. In this state, when the movable contact 9 is pulled towards left in the drawing by an operating mechanism, not shown, the contacts are separated from one the other so that an arc is produced between these contacts and the current flows through the arc. Since the arc voltage e between the contacts is increased with the increase in the distance between the contacts, a current i c given by a formulacapacitor 6. On the other hand, a current ia given by a formularcapacitor 6 so that - It is known in general that the value of a in equation (1) is higher for an arc blown by nitrogen or air than for an arc blown by SF6. Thus, in the d.c. circuit breaker shown in Fig. 3, a higher value of a can be obtained by using a gas mixture consisting essentially of SF6 and nitrogen or air as an arc blowing medium than in the case of using a gas consisting solely of SF6. Moreover, the marginal or critical temperature at which the above gas mixture is converted into the liquid phase is elevated than in the case of the SF6-gas. Thus a stronger pressure of the arc blowing gas may be used, resulting in the stronger arc blowing force and the increase in the magnitude of the right side term of the equation (1).
- It should also be noted that, while a higher pressure differential is difficult to achieve through compression with the aid of a cylinder and a piston such as buffer system a higher pressure differential can be achieved with ease with the aid of such buffer system upon addition of an SF6 gas into these gases, thus enabling the buffer blowing system to be used advantageously in conjunction with the d.c. circuit breaker.
- The mixture ratio of nitrogen or air to the SF6-gas may preferably be in the range of 20 to 80 vol. percent of nitrogen or air to the SF6-gas. The lower limit of 20 vol. percent is set because an increase in the value of a or arc voltage may not be increased for lower nitrogen or air contents while the upper limit of 80 vol. percent is set because the buffer operation ceases to be effective for higher nitrogen or air contents.
- From the foregoing it is seen that the arrangement of the present invention provides a d.c. circuit breaker having a larger current breaking capacity through the use of the gas mixture consisting essentially of SF6 gas and air or nitrogen as the arc-extinguishing and insulating medium.
Claims (3)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5824583A JPS59184414A (en) | 1983-03-31 | 1983-03-31 | Dc breaker |
JP58245/83 | 1983-03-31 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0123889A1 true EP0123889A1 (en) | 1984-11-07 |
EP0123889B1 EP0123889B1 (en) | 1988-03-09 |
Family
ID=13078730
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP84103251A Expired EP0123889B1 (en) | 1983-03-31 | 1984-03-23 | Direct current circuit breaker |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0123889B1 (en) |
JP (1) | JPS59184414A (en) |
CA (1) | CA1231774A (en) |
DE (1) | DE3469824D1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4447391C1 (en) * | 1994-12-23 | 1996-06-05 | Siemens Ag | Vacuum switch |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2798922A (en) * | 1951-07-19 | 1957-07-09 | Westinghouse Electric Corp | Circuit interrupters |
US4171474A (en) * | 1977-05-27 | 1979-10-16 | Electric Power Research Institute, Inc. | Current interrupter electrode configuration |
EP0050826A2 (en) * | 1980-10-25 | 1982-05-05 | Kabushiki Kaisha Toshiba | Circuit breaker having a parallel resistor arrangement |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5736733A (en) * | 1980-08-14 | 1982-02-27 | Tokyo Shibaura Electric Co |
-
1983
- 1983-03-31 JP JP5824583A patent/JPS59184414A/en active Pending
-
1984
- 1984-03-23 DE DE8484103251T patent/DE3469824D1/en not_active Expired
- 1984-03-23 EP EP84103251A patent/EP0123889B1/en not_active Expired
- 1984-03-30 CA CA000451036A patent/CA1231774A/en not_active Expired
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2798922A (en) * | 1951-07-19 | 1957-07-09 | Westinghouse Electric Corp | Circuit interrupters |
US4171474A (en) * | 1977-05-27 | 1979-10-16 | Electric Power Research Institute, Inc. | Current interrupter electrode configuration |
EP0050826A2 (en) * | 1980-10-25 | 1982-05-05 | Kabushiki Kaisha Toshiba | Circuit breaker having a parallel resistor arrangement |
Non-Patent Citations (1)
Title |
---|
IEEE TRANSACTIONS ON POWER APPARATUS AND SYSTEMS, vol. PAS-95, no. 1, January/February 1976, pages 140-144, IEEE, New York, US; R.D. GARZON: "The effects of SF6 - N2 mixture upon the recovery voltage capability of a synchronous interrupter" * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4447391C1 (en) * | 1994-12-23 | 1996-06-05 | Siemens Ag | Vacuum switch |
Also Published As
Publication number | Publication date |
---|---|
DE3469824D1 (en) | 1988-04-14 |
JPS59184414A (en) | 1984-10-19 |
EP0123889B1 (en) | 1988-03-09 |
CA1231774A (en) | 1988-01-19 |
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