Measuring device for measuring the effectiveness of ionizing devices and their offset voltages. Determination of the discharge time of a preselected voltage threshold value to a lower voltage value (standard +/- 1,000 V to +/- 100 V). For measuring the voltage potential on an integrated plate electrode (150 x 150 mm) using a built-in electric field meter - complies with IEC 61340-4-7 - storage of measurement data on CPM - removable plate electrode for adapting the high-voltage measuring head - high-voltage measuring head for direct voltage measurement up to 2 kV - 1 measuring device - 1 plug-in power supply unit - 1 earthing cable - 1 conductive transport case - 1 factory calibration certificate - 1 operating instructions German/English