How to Avoid Errors Caused by Heat Effects in Strain Gage Measurements when Using Scanning Units

Abstract

Excitation voltages applied to strain gages cause heat effects which may produce signal changes and measuring errors. This paper shows the most important results of many measurements which had to be taken to determine the amplitudes and time constants of these shifts of signals for different strain gage types, excitation voltages, adhesives and construction materials. In its second part the paper discusses methods of avoiding measuring errors due to heat effects and describes a scanning unit which allows to take measurements almost insensitive towards heat effects, voltage drops across the measuring leads and switching elements, or induced error voltages.