Direct-current switching device

Patent metadata

Field	Value
Publication number	US-10096443-B2
Application number	US-201414904185-A
Country	US
Kind code	B2
Filing date	Jul 2, 2014
Priority date	Jul 11, 2013
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

A direct-current switching device switches direct currents, in particular direct currents in the kiloampere range. The switching device contains a switching unit, a resonant circuit, and an overvoltage arrester. During the switching off of the switching unit, the resonant circuit produces an oscillating resonant current, which is superposed with the direct current still flowing through the switching unit during the switching off of the switching unit. Accordingly, connected in series with the switching unit, hereinafter referred to as the first switching unit, is a second switching unit, the switching behavior of which differs from the switching behavior of the first switching unit, and the resonant circuit and the arrester lie electrically in parallel with the series connection.

First claim

The invention claimed is:

1. A direct-current switching device for switching a direct current, comprising:
a switching unit;
a resonant circuit;
an overvoltage arrester;
wherein, when said switching unit is switched off, said resonant circuit generates an oscillating resonant current being superposed on a direct current still flowing through said switching unit during a switching off;
said switching unit containing a series circuit formed of a first switching unit and a second switching unit connected in series with each other, said second switching unit having a switching behavior differing from that of said first switching unit, said resonant circuit and said arrester are connected electrically parallel to said series circuit;
a delay device which, when the direct current is switched off, opens said second switching unit at a time after said first switching unit;
a drive driving both said first and second switching units; and
said delay device contains a gearing mechanism or is formed of said gearing mechanism being connected between said second switching unit and said drive, a duration of delay of said delay device and a natural frequency of said resonant circuit are matched to one another such that a switching off of said second switching unit does not start until an amplitude of the oscillating resonant current has a value of at least 75% of the direct current that is to be switched off, and/or until after a period of time that is at least three times the natural frequency of said resonant circuit.

2. The direct-current switching device according to claim 1 , wherein said first and second switching units have switching chambers, different switching behaviors of said first and second switching units are based on different physical effects in said switching chambers of said first and second switching units.

3. The direct-current switching device according to claim 1 , wherein said first switching unit generates a larger arc voltage when the direct current is switched off than does said second switching unit.

4. The direct-current switching device according to claim 1 , wherein said first switching unit is an insulating gas switching unit.

5. The direct-current switching device according to claim 1 , wherein said second switching unit is configured in such a way that said second switching unit can switch currents with a steeper current gradient at a zero crossing than can said first switching unit.

6. The direct-current switching device according to claim 1 , wherein said second switching unit is a vacuum switching unit.

7. The direct-current switching device according to claim 1 ,
wherein said delay device contains a snap-action spring mechanism or is formed of said snap-action spring mechanism that is connected between said second switching unit and said drive, said delay device is tightened during or after said first switching unit is switched off and is released to switch off said second switching unit.

8. The direct-current switching device according to claim 1 , wherein the direct-current switching device is configured for switching direct currents in the kilo-ampere range.

9. A method for switching off a direct current, which comprises the steps of:
switching-off a switching unit thus resulting in a generation of an arc, a resonant circuit being excited by an arc voltage occurring at the arc and an oscillating resonant current being generated which is superimposed on the direct current still flowing through a first switching unit during a switching off process, thus forming a superposition current;
switching off the superposition current at a zero crossing of the superposition current, and energy stored in the resonant circuit being dissipated by an arrester;
providing the switching unit with a series circuit of a first switching unit and a second switching unit whose switching behavior differs from that of the first switching unit, and the superposition current flowing through the series circuit of the first and second switching units is switched off at the zero crossing by the second switching unit;
providing a delay device which, when the direct current is switched off, opens the second switching unit at a time after the first switching unit;
providing a drive driving both the first and second switching units; and
providing the delay device with a gearing mechanism being connected between the second switching unit and the drive, a duration of delay of the delay device and a natural frequency of the resonant circuit are matched to one another such that a switching off of the second switching unit does not start until an amplitude of the oscillating resonant current has a value of at least 75% of the direct current that is to be switched off, and/or until after a period of time that is at least three times the natural frequency of said resonant circuit.

10. The method according to claim 9 , wherein the first switching unit generates a larger arc voltage when the direct current is switched off than does the second switching unit, and the second switching unit can switch oscillating currents with a steeper current gradient at the zero crossing than can the first switching unit.

11. The method according to claim 9 , which further comprises opening the second switching unit with a delay after the first switching unit.

12. The method according to claim 11 , wherein the switching off of the second switching unit does not start until an amplitude of the oscillating resonant current has a value of at least 75% of the direct current that is to be switched off, and/or until after a period of time that is at least three times a natural frequency of the resonant circuit.

13. The method according to claim 9 ,
which further comprises tightening a snap-action spring mechanism during or after the switching off of the first switching unit; and
wherein the second switching unit is switched off in that a tightened snap-action spring mechanism is released.

Assignees

• Siemens Ag

Inventors

• Jaenicke Lutz-Ruediger
• Teichmann Joerg
• Weisker Jan

Classifications

• H01H33/596 Primary

  for interrupting DC · CPC title

• Y02B70/10

  Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes · CPC title