Instruments continuity tester

Let us now look at the requirements of four often used test instruments. Continuity tester... 

Combined inspection and testing is also necessary on some equipment because some faults cannot be seen by just looking - for example, the continuity and effectiveness of earth paths on class I equipment. For some portable appliances the earth is essential to the safe use of the equipment and, therefore, all earthed equipment and most extension leads should be periodically tested and inspected for these faults. All portable appliance test instruments (PAT Testers) will carry out two important tests earth bonding and insulation resistance. 

Instruments for measuring the filament linear density continuously use capacitance of the filaments to operate the sensor, similar in principle to the Uster and Keisoki cveness testers. The instruments are usually accurate to between 1% and 3%. but as capacitance is affected by relative humidity and temperature, these parameters need to be strictly controlled. Otherwise the accuracy of the results will be somewhat spurious, even when calibration is on line, as the strict control of relative humidity within an environment where the temperature varies by more than 2 C around an ambient temperature of over 2. C is not realistic, as can be seen from any psychometric chart. 

Uster tester n. An instrument that provides a continuous measurement of the variation in weight per unit length of sliver, roving, and yarn. 

Clearly some simple method must he devised to characterize the mecheuiical response as a function of time (and of course temperature). Creep tests were a possibility hut the continued strain with time wo ild cause changes in structure and thereby make the structure-property relationship difficult to interpret. Stress relaxation was also a possibility but at that point there were instrumentation difficulties in obtaining short time measurements. What was needed was some simple method that wo ild cover a wide range of time scale of loading in which the applied strain magnitude was a controlled variable. This line of thought led to the development of the rotating beam dynamic tester ... 

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