Alternating current switch contactor

1. An electrical contactor comprising:

a first terminal having a fixed member with at least one fixed electrical contact;

a second terminal;

a busbar in electrical communication with the second terminal;

at least two electrically-conductive movable arms connected to the busbar and having a movable electrical contact thereon;

a biased-closed movable arm of at least two electrically-conductive movable arms being preformed and preloaded to be biased towards with the said at least one fixed electrical contact in the absence of a separating force; and

a biased-open movable arm of at least two electrically-conductive movable arms being preformed and preloaded to be biased away from the said at least one fixed electrical contact in the absence of a closing force,

wherein the biased-closed and biased-open movable arms and the busbar being arranged so that, when the contacts close, contra-flowing current urges the movable arms towards the fixed member to increase a force between the contacts.

2. The contactor of claim 1 , wherein ends of the movable arms and the busbar are curved to a same direction.

3. The contactor of claim 1 , wherein the busbar and the movable arms have matching or substantially matching profiles.

4. The contactor of claim 1 , wherein the movable arms include flexible repulsive portions along at least part of their longitudinal extents, the flexible repulsive portions being urgable by a repulsive force between the movable arms and the busbar which urges the movable arms away from the busbar proximally of the movable electrical contacts.

5. The contactor of claim 1 , wherein each movable arm is arranged to carry at least substantially equal current.

6. The contactor of claim 1 , further comprising an actuator arrangement for positively retaining at least the biased-closed movable arm in spaced-relationship with the fixed electrical contact.

7. The contactor of claim 1 , wherein the actuator arrangement, in a contacts-open condition, positively biases the biased-closed movable arm away from the fixed electrical contact.

8. The contactor of claim 7 , wherein the actuator arrangement, in a contacts-closed condition, positively biases the biased-open movable arm towards the fixed member, so that the contacts close.

9. The contactor of claim 7 , further comprising a distal extension element which extends from the biased-open movable arm distally of the movable contact.

10. The contactor of claim 9 , wherein the distal extension element is L-shaped, so as to be cantilevered from a distal end of the biased-open movable arm.

11. The contactor of claim 10 , wherein a distal end of the distal extension element is at or adjacent to a plane of an off-side edge of the biased-closed movable arm.

12. The contactor of claim 6 , wherein the actuation arrangement includes a leaf-spring element for biasing the biased-open movable arm to close with the fixed contact.

13. The contactor of claim 7 , wherein the actuator arrangement includes an AC dual-coil actuator, one said coil being arranged to open and close the electrical contacts and a second said coil being arranged to provide feedback, and the second said coil being directly feedback connected to an AC common center of the AC dual-coil actuator to induce a reverse flux; so that the opening and closing of the contacts is synchronized or substantially synchronized with the AC waveform zero-crossing.

14. The contactor of claim 13 , wherein the AC dual-coil actuator is an H-armature actuator.

15. The contactor of claim 14 , further comprising an AC power supply for energizing the said first coil of the AC dual-coil actuator, the in use AC power supply outputting half-cycle waveform drive pulses to the first drive coil, so as to reduce erosion energy applied between contacts.

16. The contactor of claim 14 , further comprising an AC power supply for energizing the said first coil of the AC dual-coil actuator, the in use AC power supply outputting quarter-cycle waveform drive pulses to the first drive coil, so as to prevent contact separation prior to peak load current.

17. The contactor of claim 1 , wherein each movable arm includes at least two electrically-conductive overlying layers, thereby reducing a flexure force.

18. The contactor of claim 17 , wherein the overlying layers extend over at least a majority of a longitudinal extent of the movable arm, and are solely interconnected at or adjacent to their respective proximal and distal ends.

19. The contactor of claim 18 , wherein three said electrically-conductive overlying layers are provided interengaged at their respective proximal and distal ends.

20. A movable electrical contact set comprising an electrically-conductive busbar; at least two electrically-conductive movable arms connected to the busbar and having a movable electrical contact thereon; and at least one fixed electrical contact; a biased-closed movable arm of at least two electrically-conductive movable arms being preformed and preloaded to be biased towards the said at least one fixed electrical contact in the absence of a separating force; a biased-open movable arm of at least two electrically-conductive movable arms being preformed and preloaded to be biased away from the said at least one fixed electrical contact in the absence of a closing force; and the biased-closed and biased-open movable arms and the busbar being arranged so that, when the contacts close, contra-flowing current urges the movable arms away from the busbar to increase a force between the contacts.