Electrical activity sensor device for detecting electrical activity and electrical activity monitoring apparatus
An electrical activity sensor attachable to a power cable of an electrical device for detecting an impulse generated in the power cable in response to a change in electrical power state of the electrical device, the electrical activity sensor comprising an antenna assembly comprising an antenna element operable to magnetically couple with an electrical pulse generated in the power cable to induce an electrical signal in response to a change in electrical power state of the electrical device; and at least one dipole type antenna configured operate as a half wave dipole in the operating frequency range of the antenna element and to magnetically couple to the antenna element wherein the dipole type conductor is operable to wirelessly transmit data representative of the power state change of the electrical device to a remote reader.
1. An electrical activity sensor attachable to a power cable of an electrical device and comprising an antenna assembly including
an antenna element operable to magnetically couple with an electrical pulse generated in the power cable in response to a change in electrical power state of the electrical device to induce an electrical signal; and
at least one dipole type antenna configured to operate as a half wave dipole in the operating frequency range of the at least one dipole type antenna and to magnetically couple to the antenna element wherein the at least one dipole type antenna is operable to wirelessly transmit data representative of the power state change of the electrical device from the antenna element to a remote radio frequency data reader.
2. The electrical activity sensor according to claim 1 wherein the antenna element is a loop antenna.
3. The electrical activity sensor according to claim 1 wherein the antenna element is provided with a radio frequency identification circuit comprising memory.
4. The electrical activity sensor according to claim 3 wherein the antenna element is coupled to the at least one dipole type antenna at a coupling distance x from one end of the at least one dipole type antenna, the coupling distance being based upon the input impedance of the radio frequency identification circuit.
5. The electrical activity sensor according to claim 4 wherein the coupling distance x is such that the input impedance of the antenna assembly matches the input impedance of the radio frequency identification circuit.
6. The electrical activity sensor according to claim 4 wherein the coupling distance x is based upon the radiation resistance of the at least one dipole type antenna.
7. The electrical activity sensor according to claim 6 wherein the coupling distance x is such as to increase the radiation resistance of the at least one dipole type antenna.
8. The electrical activity sensor according to claim 3 wherein the size of the antenna element is adjusted according to the input impedance of the radio frequency identification circuit at the RF operating frequency.
9. The electrical activity sensor according to claim 3 wherein the distance between the antenna element and the at least one dipole type antenna is adjusted according to the input impedance of the radio frequency identification at the RF operating frequency.
10. The electrical activity sensor according to claim 1 wherein the at least one dipole type antenna is formed in a helical shape.
11. The electrical activity sensor according to claim 1 comprising a plurality of dipole type antennas, with at least one dipole type antenna being arranged on each side of a loop antenna.
12. The electrical activity sensor according to claim 11 wherein the dipole type antennas are arranged to overlap at least partially.
13. The electrical activity sensor according to claim 1 wherein the at least one dipole type antenna has at least one fold in its shape.
14. The electrical activity sensor according to claim 1 wherein the at least one dipole type antenna is arranged to extend along at least two sides of the antenna element.
15. The electrical activity sensor to claim 1 , wherein the antenna element comprises a near field RFID tag.
16. An electrical activity monitoring apparatus for monitoring the electrical power status of at least one electrical device connected to a power supply network by a respective power cable and, the electrical activity monitoring apparatus comprising:
a reader module for reading data received wirelessly from an antenna sensor device attached to a respective power cable of an electrical device wherein the data is received from the antenna sensor device via wireless transmission from a dipole type antenna of the antenna sensor device magnetically coupled to an antenna of the antenna sensor device and the data is representative of electrical power status change of the electrical device; and
a monitor device for determining from the data received by the reader module, which electrical devices of the network have changed electrical power status.
17. An electrical activity monitoring system comprising
at least one electrical activity sensor, each electrical activity sensor being attachable to a power cable of an electrical device and comprising an antenna assembly including
an antenna element operable to magnetically couple with an electrical pulse generated in the power cable in response to a change in electrical power state of the electrical device to induce an electrical signal; and
at least one dipole type antenna configured to operate as a half wave dipole in the operating frequency range of the at least one dipole type antenna and to magnetically couple to the antenna element wherein the at least one dipole type antenna is operable to wirelessly transmit data representative of the power state change of the electrical device from the antenna element;
a reader module for reading data received wirelessly from each electrical activity sensor; and
a monitor device for determining from the data received by the reader module, which electrical devices of the network have changed electrical power status.