A Retrofit 60-Hz Current Sensor for Non-Intrusive Power Monitoring at the Circuit Breaker

Technology     

The invention is a new sensor for non-intrusive power monitoring that measures current flow in a circuit breaker without modifying the breaker panel or the circuit breaker itself. The sensor consists of three main parts: an inductive pickup for sensing current from the breaker face, an inductive link designed to transmit power through the steel breaker panel door, and a passive balanced Junction Gate Field-Effect Transistor (JFET) modulator circuit for transmitting information through the inductive link. A Non-Intrusive Load Monitoring system (NILM) interfaces with the sensor and measures the frequency content of transient events in the current signals from a centralized site. This retrofit system allows the power distribution system to non-intrusively and cost-effectively monitor multiple loads from a single location, all with the use of the presented device.     

Problem Addressed    

Current wrap-around magnetic field sensors are impractical to use as retrofit solutions to existing power monitoring systems and are further constrained by specific safety regulations related to electrical devices. The technology presented is an alternative to the wrap-around magnetic field sensor. It measures the current in the utility feed by sensing the resulting magnetic field at the face of the main circuit breaker. As a result, the device not only adapts to any load monitoring system, but also complies with safety regulations for circuit breakers.  

Advantages

• High-precision and centralized load monitoring
• Low-cost retrofit design for existing power monitoring systems
• Complies with safety regulations