HAEFEL TEST ONYX User Manual - page 23
ONYX Electrostatic Discharge Simulator
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5.6 Discharge detection and Threshold setting
The ONYX provides appropriate feedback and warnings with regards to whether a discharge to EUT has occurred.
In contact discharge mode, whether a valid discharge occurred or not can normally only be detected by using the
"Threshold” function.
For example, doing a contact discharge test on an EUT having coated metallic enclosure, it is required that the test tip
penetrates the coating, so that a real discharge to EUT may occur. If there is no electrical contact between test tip and
EUT enclosure, there will be no discharge to the EUT. Normally, the user may not detect by himself whether there was
a discharge to EUT or not. No discharge means that EUT was in fact not tested correctly.
In air discharge mode, the user normally can detect if there was a flashover from the test tip to the EUT or not.
However, even if a flashover occurred, the energy from HV-capacitor may be discharged only partly. Depending on the
users requirements, also for air discharge mode the "Threshold" function may be useful.
Figure 13 below displays different "Threshold" levels. If for example a test is performed with a "Threshold" level of
"HV -10%", then the ONYX will check the HV-capacitor voltage level before the trigger, and compare it to the voltage
level following the release of the trigger. If the drop exceeds 10%, then the ONYX will automatically assume a valid
discharge and Counter will be changed by 1 impulse.
If the 10% is not exceeded, indicating that the HV-capacitor did not discharge to the desired level, the ONYX will
assume an invalid discharge and will issue the appropriate warnings and actions as described below.
If no valid discharge occurs then the beeper will beep once, the counter will not change value, and the test will stop.
Release and press again the trigger to restart the test.
A valid air or contact discharge is confirmed by the “kV” indication next to the selected voltage display value. Once a
valid discharge occurs, the “kV” indication is highlighted as shown in figure 12.
If “Threshold” is on "OFF" position (only possible with contact discharge mode), the ONYX will run through the test
sequence but there will be no indication whether an actual discharge has occurred.
In "auto air discharge" mode, "Threshold" setting is fixed at "20%".
The individual users will need to judge which “Threshold” level is appropriate for their test depending on their
requirements.
Please note: As conditions changes with specific EUT, test voltage, approach speed (for air discharge), polarity, test
setup, temperature, humidity, etc, Threshold %-value (HV –XX%) may be only an approximation.
Fig. 13 Threshold