A Method to Determine Control Limit and to Monitor the Resistance Value of a Multiproduct Calibrator

Abstract

Abstract Monitoring of the dc resistance value of a multiproduct calibrator had been implemented. This multiproduct calibrator is commonly used as a reference standard to calibrate electrical measurement testers such as insulation tester, earth tester, continuity tester, ground bond resistance tester and many other resistance meters. The monitored value of the multiproduct calibrator can be used to support measurement traceability needs for those electrical measurement testers and meters in a power distribution utility. The monitoring was done by measuring nine data of resistance value within nine respective days to constructa preliminary statistical control limits. The measurement was continued monthly to monitor the dc resistance value that was intended to test the control limits. The monitoring is performed by doing F-test and T-test on the recent measurement data over the all previous measurement data. If a measurement data is found to be outside the control limits, an action should be done to accommodate the information and renew the statistical control limits. The renewal action for the dc resistance value of the observed multiproduct calibrator was performed for several times within a year. It is reported based on the method implementation acquired within a year, that the upper control limit (UCL) and the lower control limit (LCL) for the dc resistance value of 19 kΩ is 18.99964 kΩ and 18.99912 kΩ. Moreover, to verify the performance of the final statistical control limits, the additional measurement is taken and the result lies between the UCL and LCL