Patent ID: 7521944
Filing Date: 2009-04-21
Classification: G01M,H05K

Abstract:
1. A method of detecting fluid in a terminal block of a field device, the method comprising: measuring an initial impedance of a current loop connecting the field device to a control room when no fluid is present in the terminal block of the field device, wherein the current loop is connected to the field device by first and second terminals located in the terminal block of the field device; selecting a threshold AC voltage magnitude value based on the measured initial impedance of the current loop in which no fluid is present in the terminal block; applying an alternating current (AC) test signal at a selected frequency to the current loop; measuring a resulting AC voltage magnitude in response to the AC test signal; and detecting a change in impedance of the current loop by comparing the AC voltage magnitude measured in response to the AC test signal to the threshold AC voltage magnitude selected based on the initial impedance of the current loop, wherein a detected change in the impedance of the current loop indicates the presence of fluid in the terminal block between the first and second terminals.