Bypass switch for HVDC transmission

1. A bypass switch for high voltage direct current (HVDC) transmission, the bypass switch comprising:

a housing;

a fixed contactor disposed in the housing and electrically connected to a first portion of an HVDC transmission circuit;

a movable contactor movably disposed in the housing at a position spaced apart from the fixed contactor and electrically connected to a second portion of the HVDC transmission circuit;

an insulation member coupled to the movable contactor;

an explosive actuator configured to be exploded according to an electrical signal; and

a piston mechanism configured to:

move in response to a force applied by gas generated due to explosion of the explosive actuator;

apply a force to cause movement of the insulation member and

cause the fixed contactor and moveable contactor to be electrically connected to each other,

wherein the piston mechanism comprises:

a piston member configured to be moved in response to the force applied by the gas; and

a magnetic member coupled to and positioned between the insulation member and the piston member and configured to transfer force from the piston member to the insulation member.

2. The bypass switch according to claim 1 , wherein the explosive actuator comprises

an inflator injecting gas, and

an inflator cover coupled to the inflator,

wherein the inflator cover includes an inner space in which the gas injected from the inflator flows to the piston member and the piston member is movably disposed.

3. The bypass switch according to claim 1 , further comprising a magnet holding the magnetic member such that the magnetic member is inserted into the magnet and the movable contactor is spaced apart from the fixed contactor before the explosive actuator operates.

4. The bypass switch according to claim 1 , wherein the magnetic member is provided in a cylindrical shape, and a magnet is provided in a shape of a hollow cylinder such that the magnetic member is disposed therein.

5. The bypass switch according to claim 1 , further comprising a frame defining a space accommodating the housing, wherein a magnet is disposed in the frame.

6. The bypass switch according to claim 1 , further comprising a spring disposed around a magnet and applying force to the insulation member.

7. The bypass switch according to claim 6 , comprising:

a first frame;

a second frame;

a third frame coupled to the fixed contactor and supported by the first and second frames; and

a fourth frame coupled to the explosive actuator and supported by the first and second frames.

8. The bypass switch according to claim 7 , wherein the magnet is coupled to and supported by the fourth frame, and the spring is disposed between the insulation member and the fourth frame.

9. The bypass switch according to claim 1 , further comprising:

a first bussbar electrically connected to the fixed contactor; and

a second bussbar electrically connected to the movable contactor.

10. The bypass switch according to claim 9 , wherein the second bussbar is disposed between the movable contactor and the insulation member and contacts the movable contactor and the insulation member.

11. The bypass switch according to claim 10 , wherein the insulation member includes a protrusion which penetrates a through hole provided in the second bussbar and is coupled to an insertion groove provided in the movable contactor.

12. The bypass switch according to claim 1 , wherein the housing is a vacuum housing and further comprises a bellows disposed between the movable contactor and the housing in the housing.

13. The bypass switch according to claim 12 , wherein the vacuum housing is formed of an insulation material.

14. The bypass switch according to claim 1 , further comprising a frame defining a space accommodating the housing, wherein the explosive actuator is disposed in the frame.

15. A bypass switch for high voltage direct current (HVDC) transmission, the bypass switch comprising:

a frame defining a space therein; a housing disposed in the space;

a fixed contactor disposed in the housing;

a first bussbar connected to the fixed contactor;

a movable contactor movably disposed in the housing at a position spaced apart from the fixed contactor;

a second bussbar connected to the movable contactor;

an insulation member coupled to the movable contactor;

an explosive actuator disposed in the frame and configured to be exploded according to an electrical signal;

a piston mechanism configured to:

move in response to a force applied by gas generated due to explosion of the explosive actuator

apply a force to cause movement of the insulation member; and cause the moveable contactor to make contact with the fixed contactor; and

a spring disposed between the insulation member and the frame and configured to apply force to the insulation member,

wherein the piston mechanism comprises:

a piston member configured to be moved in response to the force applied by the gas; and

a magnetic member coupled to and positioned between the insulation member and the piston member and configured to transfer force from the piston member to the insulation member.

16. The bypass switch according to claim 15 , wherein the frame comprises a through hole into which a portion of the explosive actuator is inserted.

17. The bypass switch according to claim 15 , further comprising a magnet disposed in the frame and holding the magnetic member such that the magnetic member is inserted into the magnet and the movable contactor is spaced apart from the fixed contactor before the explosive actuator operates.

18. The bypass switch according to claim 15 , wherein the spring is positioned at an outer circumferential surface of a magnet.