Emergency lighting system
First Claim
1. A system for controlling the operation of an emergency device connected to a power line having a switch therein comprising a secondary power source for powering said emergency device, means for detecting a first loss-of-power condition resulting from the opening of said switch and a second loss-of-power condition resulting from a line failure even when said switch is closed, means responsive to the detection only of said second condition for enabling the continued powering of said emergency device from said secondary power source, said secondary power source, said detecting means and said enabling means all being contained at the location of said emergency device, control means for initially causing said emergency device to be powered from said secondary power source immediately responsive to the loss of power on said power line, and means for controlling said enabling means to operate only a predetermined time interval after said loss of power.
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Accused Products
Abstract
There is disclosed an emergency lighting system which is capable of distinguishing between a loss of power due to the opening of a line switch, and a loss of power resulting from a line failure when the switch is closed. A secondary power source powers the light in the event of a line failure. Thus when the line switch is open, i.e., when emergency lighting is not necessary, the light is not powered by the secondary source.
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Citations
48 Claims
- 1. A system for controlling the operation of an emergency device connected to a power line having a switch therein comprising a secondary power source for powering said emergency device, means for detecting a first loss-of-power condition resulting from the opening of said switch and a second loss-of-power condition resulting from a line failure even when said switch is closed, means responsive to the detection only of said second condition for enabling the continued powering of said emergency device from said secondary power source, said secondary power source, said detecting means and said enabling means all being contained at the location of said emergency device, control means for initially causing said emergency device to be powered from said secondary power source immediately responsive to the loss of power on said power line, and means for controlling said enabling means to operate only a predetermined time interval after said loss of power.
- 22. A system for controlling the operation of a particular one of a plurality of lights connected to a power line having a switch therein comprising a secondary power source for powering said light, means operative only when said switch is closed for detecting a loss of power on said line, means responsive to the operation of said detecting means for controlling the subsequent powering of said light from said secondary power source, said secondary power source, said detecting means and said controlling means all being contained at the location of said light, and impedance means connected across said line on the side of said switch remote from said light, and wherein said detecting means operates in accordance with the impedance seen looking into said impedance means through said switch.
- 36. A system for controlling the operation of a light connected to a power line having a switch therein comprising a secondary power source for powering said light, means responsive to a loss of power on said line for controlling said secondary power source to power said light, means for detecting an open condition in said switch for inhibiting the operation of said controlling means, said secondary power source, said controlling means and said inhibiting means all being contained at the location of said light, and impedance means connected across said line on the side of said switch remote from said light, and wherein said inhibiting means operates in accordance with the impedance seen looking into said impedance means through said switch.
Specification