Active rfid asset tracking tag with current-sensing cable clamp
AssigneeEmanate Wireless, Inc.
InventorGary L. Sugar
Life of this patent
Estimating the term…
Abstract
Configurations are provided for measuring electrical current flow through an AC power cable to a host device. An enclosure is provided that includes various components, such as components of an active RFID tag. A cable clamp is provided that is configured to attach the enclosure to the AC power cable. The cable clamp includes magnetic sensors that are responsive to electrical current flowing through the AC cable to generate signals indicative of the current flowing through the AC cable.
Claims11
A method for measuring the electrical current flowing through an electrical power cable, comprising:
- affixing a single magnetic field sensor to an outer insulator of the electrical power cable, wherein the outer insulator of the electrical power cable is wrapped around two or more insulated inner conductors carrying electrical current in equal but opposite directions in the electrical power cable;
- physically constraining the magnetic field sensor to the outer insulator of the electrical power cable so that it does not change position for a period of time;
- obtaining a first plurality of magnetic field strength measurements from the magnetic field sensor while it is physically constrained to the outer insulator of the electrical power cable;
- calculating a root mean squared (RMS) of the first plurality of magnetic field strength measurements;
- and
- deriving a measure of the electrical current flowing through the electrical power cable based on the RMS of the first plurality of magnetic field strength measurements.
An apparatus comprising:
- a single magnetic field sensor configured to be affixed to an outer insulator of an electrical power cable, wherein the outer insulator of the electrical power cable is wrapped around two or more insulated inner conductors carrying electrical current in equal but opposite directions in the electrical power cable;
- an analog-to-digital converter coupled to an analog output of the single magnetic field sensor and configured to convert the output to a digital output;
- and
- a processor coupled to the analog-to-digital converter to receive the digital output of the analog-to-digital converter for a first plurality of magnetic field strength measurements from the magnetic field sensor while it is physically constrained to the outer insulator of the electrical power cable, to compute a root mean squared (RMS) of the first plurality of magnetic field strength measurements and to derive a measure of the electrical current flowing through the electrical power cable based on the RMS of the first plurality of magnetic field strength measurements.
A method for charging a battery, comprising:
- affixing at least one magnetic sensor to an outer insulator of an electrical power cable, wherein the outer insulator is wrapped around two or more insulated inner conductors carrying electrical current in equal but opposite directions through the electrical power cable;
- physically constraining the at least one magnetic sensor to the outer insulator of the electrical power cable so that it does not change position over a period of time;
- rectifying, filtering and regulating an output of the magnetic sensor to obtain a regulated DC voltage;
- and
- recharging a battery with the regulated DC voltage.
Dependencies are inferred from the claim text.