Method and apparatus for switching a load between two power sources
OwnerMark Matyacinventor
Life of this patent
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Abstract
In an apparatus for selectively coupling a load to a grid power source and an inverter that is fed electric power by an alternate power source, a node is coupled to the load. A grid sensor senses the grid power source. A grid relay selectively couples grid power to the node. An inverter relay also selectively couples the inverter to node. A controller closes the grid relay and the inverter relay when grid power is available. The controller opens the grid relay when grid power is not available. The controller opens the inverter relay when grid power is not available and when feedback indicates that the grid relay is closed.
Claims20
An apparatus for selectively coupling a load to a grid power source and an inverter that is fed electric power by an alternate power source, comprising:
- (a) a first node, configured to be coupled to the load;
- (b) a grid sensor that senses a state of the grid power source;
- (c) a grid relay that couples the grid power source to the first node when in a closed state and that decouples the grid power source from the first node when in an open state;
- (d) an inverter relay that couples the inverter to the first node when in a closed state and that decouples the inverter from the first node when in an open state;
- and
- (e) a controller that is responsive to the grid sensor and that is programmed to:
- (i) cause the grid relay to be in the closed state and cause the inverter relay to be in the closed state when the grid sensor indicates power is available from the grid;
- (ii) cause the grid relay to be in the open state when the grid sensor indicates that power is not available from the grid;
- and
- (iii) cause the inverter relay to be in the open state when the grid sensor indicates power is not available from the grid and when feedback from the grid relay indicates that the grid relay is in the closed state.
A system for selectively coupling a load to a grid power source that delivers power on a first grid power line and a second grid power line that is 180° out of phase with the first power line and an inverter that is fed electric power by an alternate power source and that delivers power on a first inverter power line and a second inverter power line that is 180° out of phase with the first power line, comprising:
- (a) a first sub-node, configured to be coupled to a first phase contact of the load and a second sub-node, configured to be coupled to a second phase contact of the load;
- (b) a first grid sensor that senses a state of the first grid power line and a second grid sensor that senses a state of the second grid power line;
- (c) a grid relay that selectively couples the first grid power line to the first sub-node and the second grid power line to the second sub-node;
- (d) an inverter relay that selectively couples the first inverter power line to the first sub-node and the second inverter power line to the second sub-node;
- (e) a controller that receives feedback from the grid relay and is responsive to the grid sensor and that is programmed to:
- (i) cause the grid relay to couple the first grid power line to the first sub-node and the second grid power line to the second sub-node when the first grid sensor indicates power is available from the first grid power line and from the second grid power line;
- (ii) cause the grid relay to decouple the first grid power line from the first sub-node and the second grid power line from the second sub-node when the first grid sensor indicates power is not available from the first grid power line and from the second grid power line;
- and
- (iii) cause the inverter relay to decouple the first inverter power line from the first sub-node the second inverter power line from the second sub-node when the first grid sensor indicates power is not available from the first grid power line and from the second grid power line and when the feedback from the grid relay indicates that the either the first grid power line is coupled to the first sub-node or the second grid power line is coupled to the second sub-node.
A method of switching a load between a grid power source and an alternative power source, comprising the steps of:
- (a) sensing a state of the grid power source;
- (b) if the sensing step indicates that power is available from the grid power source then coupling both the grid power source and the alternative power source to the load;
- (c) if the sensing step indicates that power is not available from the grid power source then:
- (i) decoupling the grid power source from the load;
- (ii) sensing if the grid power source is decoupled from the load after the step of decoupling the grid power source from the load;
- (iii) if the grid power source is decoupled from the load, then coupling the alternative power source to the load;
- and
- (iv) if the grid power source is coupled to the load, then decoupling the alternative power source from the load.
Dependencies are inferred from the claim text.