Print page

A Step Closer Toward Maintenance-Free Gear

A difficult-to-predict electrical failure is the continuity failure. Pressure junctions are common problem sources for continuity failures. Available tools to search for pressure-junction problems include low-resistance testing, temperature monitoring using physical contact between sensor and heated part, pyrometer temperature monitoring, infrared photography, and visual inspection. While each method is effective, each of these methods has one or more disadvantages. This paper will describe a breakthrough patented method of directly calculating conductor and pressure-junction impedance, resistance, and reactance using the noisy harmonic-laden switching-transient-laced (in other words, normal) load current flowing through an electrical distribution system. This technique then provides the solution to the problem of how to detect a conductor-path-impedance change of only a few tens of micro-ohms using conventional protective and metering devices without the need to de-energize the equipment or without the need to inject currents.

Electrical equipment failures can be broadly divided into two types: insulation and continuity failures.

The former occurs when current flows when and where it should not. This paper will not discuss the former. A common example of the latter is an unexpected interruption or possibly even an arc Flash event if initiated by a loosening connection [1]-[7]. Available tools to search for the failing pressure connections include low-resistance ohmmeter (Ductor) testing, temperature monitoring using physical contact between sensor and heated part, pyrometer temperature monitoring, infrared photography, and visual inspection. While each method is effective, each of these methods has one or more disadvantages.

A somewhat more ideal solution would be one that is able to continuously measure the impedance of all circuit conductors, calculate the X/R ratio of those conductors, and solve for the resistance per phase of each conductor using relaying and metering already needed by, and in place on, the equipment. This resistance could then be trended over time and even compared between phases, looking for any individual phase trending away from the average over time.

Download the entire paper now to learn more.