Monroe Electronics Electrostatic Voltmeter - Isoprobe® - model 279L - Manual (Page 23)

279L-0401-RCA Page 20
APPENDIX III
HV BREAKDOWN CONSIDERATIONS
Air is subject to dielectric breakdown when the probe-to-surface spacing is small and the difference in voltage
between the probe and the surface under test is high. A destructive arc-over can occur damaging the surface under
test and/or the sensitive circuitry of the probe. Under normal operating conditions this is usually not a problem as
the probe housing is driven to a voltage essentially identical to the unknown and the difference in voltage is very
close to zero.
Under normal circumstances the Model 279 ISOPROBE ® Electrostatic Voltmeter can follow the unknown voltage up
to its high voltage amplifier limits — a few hundred volts above its specified range of ±3000 volts.
Figure A-III-1