Fusible switch disconnect device for DC electrical power system
A fusible disconnect switch devices includes dual sets of switch contacts to connect or disconnect a current path through an overcurrent protection fuse with reduced arcing severity. Faster acting and longer contact path switch mechanisms are described providing satisfactory switching of DC circuits without excessive electrical arcing in a reduced physical package size.
1. A fusible switch disconnect device comprising:
a housing including opposed top and bottom surfaces, the top surface configured to receive and accept an overcurrent protection fuse and the bottom surface formed with a pocket extending from the bottom surface;
a current path defined in the switch housing and connecting to the overcurrent protection fuse when received, the current path including at least first and second stationary switch contacts proximate the bottom surface on respectively different sides of the pocket; and
a switch mechanism selectively positionable between first and second positions to connect and disconnect the current path without removing the overcurrent protection fuse, the switch mechanism comprising:
a rotary switch actuator selectively positionable between first and second positions to cause the current path to open or close while the overcurrent protection fuse is connected; and
a contact element, responsive to the position of the rotary switch actuator, and carrying at least two movable switch contacts for selective engagement with the at least first and second stationary switch contacts, wherein a portion of the contact element descends into the pocket when the current path is closed;
wherein the switch mechanism further comprises a link having a first end and a second end, the first end coupled to the rotary switch actuator and the second end coupled to the contact element;
wherein the rotary switch actuator defines an elongated guide member receiving the first end of the link, and wherein the housing comprises a cam surface cooperating with the first end of the link; and
wherein the cam surface includes at least one arcuate portion.
2. The fusible switch disconnect device of claim 1 , wherein the contact element carrying at least two movable switch contacts includes dual pairs of movable switch contacts.
3. The fusible switch disconnect device of claim 1 , wherein the contact element is a slider bar movable along a linear axis within the housing.
4. The fusible switch disconnect device of claim 1 , the switch mechanism further comprising a leaf spring acting on the contact element.
5. The fusible switch disconnect device of claim 4 , wherein the leaf spring includes forked ends.
6. The fusible switch disconnect device of claim 1 , wherein the cam surface further includes at least one linear portion.
7. The fusible switch disconnect device of claim 6 , wherein the linear portion extends parallel to an axis of motion of the contact element.
8. The fusible switch disconnect device of claim 1 , wherein the at least one arcuate portion is designed to over-compress the at least two movable switch contacts when engaged to the at least first and second stationary switch contacts.
9. The fusible switch disconnect device of claim 1 , wherein the elongate guide member defines a slot.
10. The fusible switch disconnect device of claim 9 , wherein the first end of the link may rotate and translate relative to the slot.
11. The fusible switch disconnect device of claim 9 , wherein the slot is an elongated linear slot.
12. The fusible switch disconnect device of claim 1 , wherein the second end of the link may rotate, but not translate, relative to the contact element.
13. The fusible switch disconnect device of claim 1 , wherein the link is a linear link.
14. The fusible switch disconnect device of claim 1 , wherein the link extends obliquely to an axis of motion of the contact element when the switch actuator is in the first position.
15. The fusible switch disconnect device of claim 1 , wherein the link extends parallel to an axis of motion of the contact element when the switch actuator is in the second position.
16. The fusible switch disconnect device of claim 1 , wherein the cam surface includes a first portion and a second portion extending perpendicular to the second portion.
17. The fusible switch disconnect element of claim 1 , wherein the housing is configured to accept a rectangular overcurrent protection fuse module having plug-in terminal blades.
18. A fusible switch disconnect device comprising:
a housing including opposed top and bottom surfaces, the top surface configured to receive and accept an overcurrent protection fuse and the bottom surface formed with a pocket extending from the bottom surface;
a current path defined in the switch housing and connecting to the overcurrent protection fuse when received, the current path including at least first and second stationary switch contacts proximate the bottom surface on respectively different sides of the pocket; and
a switch mechanism selectively positionable between first and second positions to connect and disconnect the current path without removing the overcurrent protection fuse, the switch mechanism comprising:
a rotary switch actuator selectively positionable between first and second positions to cause the current path to open or close while the overcurrent protection fuse is connected; and
a contact element, responsive to the position of the rotary switch actuator, and carrying at least two movable switch contacts for selective engagement with the at least first and second stationary switch contacts, wherein a portion of the contact element descends into the pocket when the current path is closed;
wherein the switch mechanism further comprises a link having a first end and a second end, the first end coupled to the rotary switch actuator and the second end coupled to the contact element;
wherein the rotary switch actuator defines an elongated guide member receiving the first end of the link;
wherein the housing comprises a cam surface cooperating with the first end of the link; and
wherein the elongated guide member defines a slot.
19. The fusible switch disconnect device of claim 18 , wherein the first end of the link may rotate and translate relative to the slot.
20. The fusible switch disconnect device of claim 18 , wherein the slot is an elongated linear slot.
21. The fusible switch disconnect device of claim 18 , wherein the cam surface includes at least one arcuate portion.
22. The fusible switch disconnect device of claim 21 , wherein the at least one arcuate portion is designed to over-compress the at least two movable switch contacts when engaged to the at least first and second stationary switch contacts.
23. The fusible switch disconnect device of claim 21 , wherein the cam surface further includes at least one linear portion.
24. The fusible switch disconnect device of claim 18 , the switch mechanism further comprising a leaf spring acting on the contact element.
25. The fusible switch disconnect device of claim 24 , wherein the leaf spring includes forked ends.
26. The fusible switch disconnect device of claim 18 , wherein the cam surface includes a first portion and a second portion extending perpendicular to the second portion.