Corona discharge tester


The XT-330 PB39a uses the corona discharge phenomenon to test the insulation of capacitors, motors, and other kinds of items, including the corona discharge withstand voltage between transformer winding wires and cores, within secondary winding wires, and between the primary and secondary sides.
The XT-330 PB39a tests for the presence of corona discharges and flashovers of test objects by generating selectable voltages (0 to 10 kVrms, tuning is required) at selectable frequencies (10 k to 100 kHz) at the HV terminal and applying this to the test object.
Because you can accurately detect corona discharges that were previously difficult to detect, we believe that this tester will be useful improving your product reliability.
It is very dangerous if there is corona discharge in a high-voltage supply circuit. You can investigate this as well with the XT-330 PB39a.
For example, it is now possible to carry out insulation testing that was previously impossible, such as for the corona discharge withstand voltage between connectors or high-voltage patterns of printed circuit boards and the chassis.
We have prepared a tuning mechanism that enables you to change the impedance of the test circuit for the capacity load of high voltage capacitors and other test items.


Along with making light and sound, flashovers consume energy, so a product clearly operates poorly.
However, corona discharges are generated by the ionization of air, and their pulse is faint. Therefore, a product may appear to operate normally, which makes corona discharge detection difficult.
However, the ozone (O3) that is created along with corona discharges has a strong oxidization power and can encourage degradation of insulation over the long term and includes the risk of creating flashovers. Therefore, it is desirable to take preventative measures for corona discharges.
The XT 330 checks for corona discharges and flashovers generated by high-voltage waveforms.
If a discharge is detected, the count is increased by one, and then displayed.

Corona dischargeDisplays 0 to 255. The count returns to 128 each time it reaches 255.(It is not indication of electric charge)

FlashoversDisplays 0 to 255. The count returns to 128 each time it reaches 255


Corona discharge tester
XT-330 PB39a

XT-330 PB39a
Test frequency
10 to 100 kHz; selectable in 1 kHz steps
Maximum test voltage
10 kVrms (Tune the drive current to its minimum with a load connected)
Drive waveform
Continuous sine wave
Load range
Capacitance load range: 350 to 1000 pF at 10 kHz;Inductance load range 10 to 100 kHz; about 300 mH or more (involved in frequency)
Continuous test voltage
Output voltage when a load is connected after tuning to the position where the drive current is smallest, and the power amp temperature is 95°C or lower
Maximum HV current
1A (Continuous is 700 mA)
HV Adj. Sensitivity adjustment of HV Impedance tuning
Drive output
Auto (with Auto Corona search function) / Manual
Drive Adj.
Output voltage manual adjustment
Minimize Drive Current in Manual mode.
Measurement types
High Voltage, Flashover, Corona, Drive Voltage, Drive Current, Wakeup Time, Real Time, HV Current
Main unit 430 (W) × 470 (D) × 180 (H) mm Packing W510×D580×H270 mm Probe box 430 (W) × 470 (D) × 180 (H) mm Packing W510×D580×270 mm
Main unit Approx. 16 kg G/Weight 21kgs Probe box Approx. 13 kg G/Weight 17kgs
Power consumption
800 VA