Large excessive current during the calibration of electrometer by use of a capacitive low-current source

Large unexpected excessive current was observed in the course of the electrometer calibration by use of a capacitive low-current source of KRISS. Simultaneously, the baseline restoration period following the switch-off of the ramp voltage of the current source was conspicuously extended. Keithley model 6517A electrometer was introduced in the calibration and the current range employed in the calibration was from 0.1 to 10 pA.