Abstract:
This invention concerns a meter for measuring polarisation induced in the earth and in particular for measuring transient voltages that follow the termination of direct current flow through the ground. In this device automatic normalisation of the data is achieved by correllating the voltage source producing the transient voltages with the potential measured across measurement electrodes in such a manner that the voltage source and measurement circuits are not otherwise electrically linked.
Abstract:
This invention concerns a device for measuring earth resistance. A constant alternating current is supplied from an inverter to a pair of spaced apart earth probes. Two further probes located between the earth probes are connected to the input stage of an amplifier having a very high input impedance so as to derive a signal which is proportional to the earths resistance. The output of the input amplifier is rectified and fed to a comparator which is also supplied a switched range of reference voltages.