ACCESSORY CONNECTABLE TO A MULTIMETER FOR THE MEASUREMENT OF EARTH RESISTANCES

摘要

The invention provides a measuring attachment connectible to a multimeter for measuring earth resistances, comprising a casing having a first group of terminals for a measurement signal and a second group of terminals for electrical connection of the attachment to a multimeter, and electric circuits housed in the casing and comprising generator means for generating an AC current of constant value but of a frequency different from that of the mains and its harmonics, said generator means having an output connected to first and second terminals of said first group of terminals, and a synchronous detector having a measurement signal input which is connected to said second terminal and to a third terminal of said first group of terminals, a control input which is connected to said generator means and an output which is connected to first and second terminals of said second group of terminals.