|Experiments: with Spark Inductor|
ATTENTION, experiments with high voltage are very dangerous!!
This page demonstrates several experiments with the Spark Inductor.
The classical interrupter (mechanical interrupter) of the Spark Inductor is short-circuited. Instead of the this an electronic interrupter is used.
This driver makes it possible to adjust , the energy fed to the primary coil of the Spark Inductor as well as the frequency the primary current flow is interrupted with.
A complete video showing all experiments is available on YouTube.
During the first experiment the energy fed to the Spark Inductor is increased step wise.
This is done in the way, that the duration is increased, the electric circuit is closed. The longer the duration the higher the energy fed to the Spark Inductor.
The distance of the electrodes is approximately 10 cm. At the beginning the energy is not sufficient to cause a spark discharge. When the energy is increased, the voltage induced in the secondary coil rises until the sparks break out. For a "sharp point – plate" arrangement, as it is used in this experiment, a high voltage of approximately 60000 V is needed to cause spark discharge.
The interrupter frequency is increased during the second part of the experiment. The number of individual discharges per time unit rises. The observer gets the impression simultaneous discharges would happen. This is caused by the inertia of the human eye.
|    low energy||    low discharge frequency||    high discharge frequency|
|    low discharge frequency||    high discharge frequency|
The second experiment demonstrates, that an electrical discharge ignites preferably, if the negative loaded cathode has a extensive shape like a flat plate. Of course the Spark Inductor does not really provide DC, but depending on the direction of the current flow through the primary coil a high voltage peak with reverse polarity is induced in the secondary coil, after the primary current flow was interrupted.
The voltage necessary to cause a spark discharge is lower, if the positive loaded electrode has the shape of a sharp point.
The sparks strike just the edge of the plate, if the plate is the positive loaded electrode.
|    Discharge with negative plate||    Discharge with positive plate|
The third experiment demonstrates, that the isolation capability of an electrical isolator depends on its position within the electrical field.
The electrical field is low in the middle between the electrodes. The isolator resists.
If the isolator is moved closer to the electrodes, the isolation breaks through even the voltage has not been changed. This is, because the electrical field is stronger nearby the electrodes.
|    Isolator in the middle||    Isolator close to sharppoint electrode||    Isolator close to plate|
The fourth experiment demonstrates the thermal effect of an electrical spark discharge.
The distance of the electrodes has been reduced slightly for this experiment.
In case of the interrupter frequency is low, the individual discharges just break through the paper. The energy is not sufficient to burn down the paper.
If the frequency of the discharges is increased, more energy is delivered to the paper.
First the paper is just burned locally. Burn holes develop.
If the frequency is continued to increase, electrical conducting gases develop.
The spark discharge becomes and arc discharge. The heat of the arc is sufficient an the paper is on fire.
|    Individual discharges||    Frequent discharges||    Arc causes fire|
|    Arc causes fire|