Method for detecting and obtaining information about changes in variables

Abstract

Detection of liquid leaks and other changes in variables is disclosed. The event causes two elongate conductors to become electrically connected at a location which is determined by the event, thus creating a system in which the connection point can be located by measuring the potential drop from one end of one of the conductors (called the locating member) to the connection point. The system comprises a balancing component so that its sensitivity is not dependent on the location of the event along an elongate path. A fixed current flows through the connection, so that the result is independent of the resistance of the connection. The locating member can be a continuous resistive wire, coated with a conductive polymer; such a locating member can form part of a sensor cable in which the elongate components of the circuit are in a wrapped configuration. Alternatively the locating member comprises a plurality of discrete resistors. The system is arranged so that only connections within a certain range of resistance will activate the system. The voltage drop is calculated by comparing it to the voltage drop over a resistor of known size. Particular event-sensitive connection means are employed for the detection of hydrocarbons.