Corona discharge tester


A high voltage occurs interlayer space when using high-frequency transformers. Therefore, particular attention needs to be paid to the layer insulation and terminal treatment. Since the transformer becomes unusable when flashover occurs, it is easy to judge it to be faulty. However, corona discharge is often over-looked because abnormalities in the operation of the transformer are almost undetectable.
When the electrical field surrounding the high-frequency electrode is high, vapour ionizes and corona discharge begins. Corona discharge can be increased through the application of a continuous pulse. The large oxidization level of the ozone that generally occurs through corona discharge promotes quickened deterioration of the insulating material, which over prolonged periods of time carries the risk of damage resulting form flashover.
This device causes an optional voltage (0 – 5kVrms, No Load) in the optional frequency (30k~80kHz) sine wave in the HV terminal, and examines the existence of the corona discharge, flashover of DUT.
It is especially useful for the reliability improvement of the product because the corona discharge that detection was difficult can be detected precisely till now.


Because Flashover( spark discharge) consumes energy accompanied by light and sound, the transformer will obviously be malfunctioned.
However, as the occurrence of corona discharge depends on ionization in the air, it is difficult to detect abnormalities in the transformer operation due to such a faint pulse. Since the ozone accompanied with corona discharge causes fast oxidization, provoking deterioration of insulating materials over long periods of time and increasing the danger of spark discharge, it is recommended that you take provisions.
This device detects the existence of corona / Flashover using high voltage wave patterns. It adds 1 point to the collective count for every discharge detected, as displayed below.

Corona DischargeThe magnification selected using Corona Rate counts in units of 1. 0 – 127 is displayed (It is not indication of electric charge)

FlashoverThe magnification selected using Flashover Rate counts in units of 1. 0-127 is displayed


Corona discharge tester
XT-310 PB3a

XT-310 PB3a
Test frequency
30kHz to 80 kHz; selectable in 1 kHz steps
Test voltage
no load 0-5.00kVrms 50k – 80kHz (using white cable)
Drive waveform
Continuous sine wave
Measurement types
High Voltage, Flashover, Corona, Drive Voltage, Drive Current, Wakeup Time, Real Time
MainUnit 430(W) × 470(D) × 180(H) mm Packing W510×D580×H270 mm ProbeBox 240(W) × 290(D) × 130(H) mm Packing W320×D320×H210 mm
MainUnit Approx. 15kg G/Weight 18.5kgs ProbeBox Approx. 5kg G/Weight 6.5kgs
Power consumption
500 VA