  This paper investigates the influence of a resistor on the dielectric
behavior of an air gap. The resistor is connected in series with the air gap
and the latter is stressed by impulse voltage. Air gap arrangements of
different geometry with either the rod or the plate grounded are stressed with
impulse voltages of both positive and negative polarity. The resistor is
connected in series with the air gap in the return circuit connecting the gap
with the impulse generator. The method followed involves the investigation of
the graphs of the charging time concerning the air gaps capacitances, in
connection to the value of the resistor, the geometry of the gap, the effect of
grounding and the polarity effect. It is determined that the charging time of
the air gap increases, as the value of the resistor increases. It is also
determined that the peak voltage value of the fully charged air gap decreases
as the value of the resistor increases. The results of the mathematical and
simulation analysis are compared with the results of the oscillograms taken
from experimental work. In addition and consequently to the above results it is
concluded from the experimental work that the in series connection of the
resistor in the circuit has significant influence on corona pulses (partial
discharges) occurring in the gap and on the breakdown voltage of the gap. A new
method of controlling the corona effects and consequently the breakdown voltage
of small air gaps stressed by impulse voltage of short duration in connection
to the ground effect and the polarity effect has arisen. Furthermore through
mathematical analysis of the charging graphs obtained from simulation and
experimental oscillograms there was a calculation of the values of the
capacitance of the air gaps in relation to their geometry and the results were
compared to the values calculated with mathematical analysis.
