Circuit breaker locator

What is this patent about?

’272 is related to the field of electrical test equipment, specifically tools used for tracing conductors and identifying specific circuit interrupters, such as breakers or fuses, within a power distribution panel. In complex wiring environments, identifying which breaker controls a specific outlet often leads to false positives due to electromagnetic coupling between adjacent wires or electrical noise from motors and dimmers. The patent addresses the need for a more reliable, noise-immune method to isolate a single branch circuit without manually tripping breakers.

The underlying idea behind ’272 is the use of a highly specific, symmetrically ramped current pulse sequence that allows a receiver to distinguish the target signal from background noise and orientation-dependent flux. By utilizing a constant current source and an integrator, the transmitter generates pulses that increase linearly, plateau at a maximum value, and then decrease linearly with a fall time identical to the rise time. This linear symmetry ensures that a differentiating pickup coil in the receiver produces consistent rectangular pulses regardless of the direction of current flow, eliminating the need for the user to rotate the probe when moving between different sides of a breaker panel.

The claims of ’272 focus on a transmitter and receiver system that induces a sequence of current pulses into a branch circuit where the pulses are separated by non-equal time intervals. Specifically, the independent claims require that each pulse has a linear rise and fall of equal duration and that the controller initiates these pulses at predefined, staggered intervals so that the spacing between successive pairs is not uniform. The receiver is claimed as a device that validates both the specific timing of these intervals and the characteristic rise or fall times of the detected pulses before alerting the user.

In practice, the transmitter acts as a current pump that creates a low-impedance load across the hot and neutral lines in a controlled, ramped fashion. Because the receiver’s pickup coil naturally differentiates the signal, the linear slopes of the current pulses are converted into rectangular voltage spikes. The system’s reliance on a multi-pulse sequence with unique spacing acts as a temporal signature; the receiver only triggers an alert if it detects the exact pattern of pulses at the correct intervals, effectively filtering out random spikes or periodic noise from other electronic devices.

This approach differs from prior solutions that typically used simple relaxation oscillators or high-frequency bursts, which are prone to interference and require manual gain adjustments to resolve ambiguity. By combining asymmetric pulse spacing with symmetric pulse shaping, the invention ensures that the receiver can identify the correct breaker even in high-noise environments. Furthermore, the identical rise and fall times solve the common industry problem of signal polarity, allowing the probe to function identically on both the left and right bus bars of a distribution panel without physical reconfiguration.