Electrical contactor
In an electrical contactor a first terminal ( 5 ) is connected to a pair of contacts ( 3, 4 ) on opposite faces of a fixed conductive member ( 2 ). A second terminal ( 6 ) is connected to a pair of movable arms ( 7, 8 ) of electrically conductive material carrying moveable contacts ( 9, 10 ) at an end remote from the connection to the second terminal ( 6 ). The movable arms ( 7, 8 ) are arranged in aligned opposition to each other and such that their remote ends are on either side of the fixed member ( 2 ) with the movable contacts ( 9, 10 ) aligned with the fixed contacts ( 3, 4 ). The arrangement of the fixed member ( 2 ) and movable arms ( 7, 8 ) is such that when the contacts are closed current flowing through the moveable arms produces a force that urges the movable arms towards each other thereby increasing the force between the fixed and movable contacts. In such a contactor overload currents cause the contact force to increase due to the attractive electromagnetic force produced between the arms ( 7, 8 ) by currents flowing in the same direction in the arms ( 7, 8 ).
1. An actuating arrangement for an electrical contactor, comprising:
a member;
a carriage coupled to the member; and
a solenoid coupled to the carriage on a same plane as the member, wherein activation of the solenoid causes the carriage to move the member in a direction parallel to the solenoid with an amount of contact force that is calculated according to an equation:
Contact Force= C F −R F +B F ,
where C F represents a preload force of parallel arms of the electrical contactor, R F represents a contact repulsion force and B F represents a electro-magnetic attraction force between the parallel arms.
2. The actuating arrangement of claim 1 , wherein R F is calculated by an equation:
R F =k c *( D/d )*(½* I sc ) 2 ,
where k c is a configuration constant, D is a contact head diameter, d is a contact touch diameter and I sc is a short circuit current.
3. The actuating arrangement of claim 1 , wherein B F is calculated by an equation:
B F =k c *( L*w/g )*(½* I sc ) 2 ,
where k c is a configuration constant, L is an active length of each arm of the electrical contactor, w is an active width of each arm, g is a nominal parallel separation between arms of the electrical contactor and I sc is a short circuit current.
4. The actuating arrangement of claim 1 , wherein the amount of contact force required is approximately 300gF.
5. The actuating arrangement of claim 1 , wherein the solenoid is coupled to the carriage via a plunger.
6. The actuating arrangement of claim 1 , wherein the electrical contactor is designed to handle currents of approximately 100 amperes.
7. A method of separating arms of an electrical contactor, comprising:
activating a solenoid; and
moving a member in a direction parallel to the solenoid via a carriage coupled to the solenoid on a same plane as the member in response to activating the solenoid with an amount of contact force that is calculated according to an equation:
Contact Force= C F −R F +B F ,
where C F represents a preload force of parallel arms of the electrical contactor, R F represents a contact repulsion force and B F represents a electro-magnetic attraction force between the parallel arms.
8. The method of claim 7 , wherein R F is calculated by an equation:
R F =k c *( D/d )*(½* I sc ) 2 ,
where k c is a configuration constant, D is a contact head diameter, d is a contact touch diameter and I sc is a short circuit current.
9. The method of claim 7 , wherein B F is calculated by an equation:
B F =k c *( L*w/g )*(½* I sc ) 2 ,
where k c is a configuration constant, L is an active length of each arm of the electrical contactor, w is an active width of each arm, g is a nominal parallel separation between arms of the electrical contactor and I sc is a short circuit current.
10. The method of claim 7 , wherein the amount of contact force required is approximately 300gF.
11. The method of claim 7 , wherein the electrical contactor is designed to handle currents of approximately 100 amperes.
12. An apparatus for use in an electrical contactor, comprising:
a member;
means for moving the member; and
means for moving the means for moving the member coupled to the means for moving the member on a same plane as the member, wherein activation of the means for moving the means for moving the member causes the means for moving the member to move the member in a direction parallel to the means for moving the means for moving the member with an amount of contact force that is calculated according to an equation:
Contact Force= C F −R F +B F ,
where C F represents a preload force of parallel arms of the electrical contactor, R F represents a contact repulsion force and B F represents a electro-magnetic attraction force between the parallel arms.
13. The apparatus of claim 12 , wherein R F is calculated by an equation:
R F =k c *( D/d )*(½* I sc ) 2 ,
where k c is a configuration constant, D is a contact head diameter, d is a contact touch diameter and I sc is a short circuit current.
14. The apparatus of claim 12 , wherein B F is calculated by an equation:
B F =k c *( L*w/g )*(½* I sc ) 2 ,
where k c is a configuration constant, L is an active length of each arm of the electrical contactor, w is an active width of each arm, g is a nominal parallel separation between arms of the electrical contactor and I sc is a short circuit current.
15. The apparatus of claim 12 , wherein the amount of contact force required is approximately 300gF.
16. The apparatus of claim 12 , wherein the means for moving the means for moving the member is coupled to the means for moving the member via a plunger.
17. The apparatus of claim 12 , wherein the electrical contactor is designed to handle currents of approximately 100 amperes.