Hioki SM-8216, Instruction Manual, Page: 36 / 44

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measurements, it takes several hours to a few days for the leakage current
to stabilize. This is not practical.
To avoid this problem, a method is customarily used in the insulation
resistance measurement for convenience to read the resistance value one
minute after charging the test voltage to the sample. This value is called
1- minute rate value for the resistance value of an insulator, and is widely
employed among a variety of electrical standards.
In the 1-minute rate insulation resistance measurement, the measured
values may vary when a measurement is repeated once or twice with the
same sample. To minimize such a deviation, it is important to completely
discharge the sample before the start of each measurement. The required
discharge time mainly depends upon the charging voltage and the size of
C
0
in Fig. 6.7.1, but, generally it can be said to be 5 to 6 times longer than
the time of test voltage charging.