CORONA-i XT-310 PB3a Surge Tester
・Corona Discharge Tester
・spark discharge Tester
・Trans for Liquid Crystal Backlight
・Connecter, Infracture, Erectric Code
・Small motor
1. Product OutlineSpecifications
9. Notes on the Measuring Device Settings
1.Product Outline
A high voltage occurs interlaminarly when using high frequency wave 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.
Corona discharge occurs even with a regular voltage and the device judges items to be unsatisfactory if there are deformities, overlapping sections (a section overlapping another), wire off-cuts (off-cut wires accidentally wrapped in the coil ), etc in the coil.
And, it is dangerous when there is a corona discharge in the feed circuit of the high voltage. This can be examined with XT-310 PB3a, too.
2.Accompanying Items
The items listed below accompany the main appliance of this system.
Probe Box PB3a qty: 1
Mains Electric Cable VCT cable containing 3 small wires qty: 1
2P-3P Exchange Adaptor qty: 1
F.GND Connecting Cable qty: 1
Probe Cable 16P Connector equipped qty: 1
High-voltage connecting cable(white) Clip (Yellow) equipped qty: 1
High-voltage connecting cable(red) Clip(Yellow)equipped qty: 1
High-voltage connecting cable(blue) Clip(Yellow)equipped qty: 1
Return Connecting Cable Clip(Blue)equipped qty: 1
Drive Cable Clip (Red & Black) equipped qty: 1
Instruction Manual qty: 1
3.Operating Guide
3-1. Discharge Detection
Because spark discharge (Flashover) 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 / sparks discharge using high voltage wave patterns. It adds 1 point to the collective count for every discharge detected, as displayed below.
Corona Discharge: The magnification selected using Corona Rate counts in units of 1.0 – 127 is displayed.
Spark Discharge: The magnification selected using Flashover Rate counts in units of 1.0 – 127 is displayed.


Drive frequency 30kHz 80kHz 1kHz step selectable
Drive voltage 0 – 40.0Vrms (manually variable)
Drive current 0 – 3.0Arms (40.0Vrms)
3.0 – 5.0Arms (15Vrms)
Drive waveform Sine wave
HV output voltage (no load 0 – 5.00kVrms 50k – 80kHz (using white cable)
22pF load 0 – 5.00kVrms 36k – 50kHz (using red cable)
47pF load 0 – 5.00kVrms 30k – 36kHz (using blue cable)
Output inductance 300mH +-20%
Display High Voltage 0 – 5.00kVrms
Flashover 0 – 127 count
Corona 0 – 127 count
Drive Voltage 0 – 40.0kVrms

Drive Current 0 – 5.0Arms
Wakeup Time 0 – 99.9s (0 means unlimited)
Real Time 0 – 99.9s (0 means unlimited)
Monitor Output HHigh Voltage High-voltage waveform
Flashover Spark discharge waveform
Drive Voltage Drive Voltage Waveform

Corona Corona Discharge Waveform
Sync. out Synchronized signal
Adjustments HV Adj.
Corona Rate 0 – 7
Flashover Rate 0 – 7
Remote Connector
RS-232C Connector
Drive Mode Selector Auto / Manual
Measurement Types High Voltage, Flashover, Corona, Drive Voltage, Drive Current, Wakeup Time, Real Time
Dimensions 430 (W) x 470 (D) x 180 (H) mm (main housing)
240 (W) x 290 (D) x 130 (H) mm (Probe Box PB3a)
Mass 15kg (main unit)
5 kg (Probe Box PB3a)
Electrical requirements 500VA
Environment Operating ambient temperature 15 deg C to 35 deg C
Operating humidity 30% to 80%(no condensation)
Storage temperature -20 deg C to 80 deg C
Storage Humidity 10% to 80%(no condensation)
Rated power supply voltage AC100V, 220V (specified in advance)
Admissible fluctuations in power supply voltage Rated power supply voltage +-10%
5.Part names
5-1. Front Panel


1 Active Lamp Lights up when high-voltages are present
2 Probe Terminal Connectable to the probe box using a probe cable
3 Power switch
4 FL display tube
5 Test lamps These light green for good and red for bad depending on each particular item
6 Start button When pressed measurement begins
7 Stop button When pressed measurement ends
8 Synthesized-test lamps These light green or red depending on the quality of the transformer
9 Frequency selectivity Use to select the frequency supplied to the primary side that is to be measured.
10 Mode Selector Interchangeable between Auto / Manual
11 Drive Adj. Use to adjust the voltage supplied to the primary side that is to be measured (in Manual mode)
12 Keyboard
5-2. Rear Panel

1 HV Adj HV Voltage indicator valve calibrations are performed here
2 Corona Rate The rate of the corona discharge count is selected here
Corona Rate 0 1 2 3 4 5 6 7
Magnification 1 2 4 8 16 32 64 128
3 Flashover Rate The rate of the flashover count is selected here
Flashover Rate 0 1 2 3 4 5 6 7
Magnification 1 2 4 8 16 32 64 128
4 High Voltage Monitor output of the secondary transformer voltage.
Approximately 1/2000 of the actual voltage is output
5 Corona The location of corona discharge detection
6 Drive Viltage Monitor output of drive voltage
7 Flashover Monitor output of flashover
8 Sync.out Synchronized monitor output
9 Remote Remote terminal
10 RS-232C Test data can be moved to a PC by connecting to a PC serial port.
11 F.GND Frame ground
12 Fuse 250V 5A
13 AC INPUT 100V
5-3. RS-232C Specifications
1)Baud rate   9600bps
2)Start bit   1bit
3)Stop bit   2bit
4)Data length  8bit
5)Parity check  none
6)Data code   ASCII
7)Handshaking  none
(The characters enclosed with ” mark below indicate that content will be output in the same way as written)
Data transmitted after switching the power on
___From Here___
“POWER ON, CORONA-i XT-310 ,” version number
CR Code (13)
LF Code (10)
___Until Here___
Data output when measurement begins
___From Here___
CR Code (13)
LF Code (10)
___Until Here___
Data output when measurement ends
___From Here___
“HV ,Flashover,Corona,Drive C ,Drive V,W.-up Time,R.Time,”
HighVoltage Measurement value
FlashOver Measurement value
Corona Measurement value
DriveCurrent Measurement value
DriveVoltage Measurement value
WakeupTime Measurement value
RealTime Measurement value
HighVoltage Upper limit
HighVoltage Lower limit
FlashOver Upper limit
FlashOver Lower limit
Corona Upper limit
Corona Lower limit
DriveCurrent Upper limit
DriveCurrent Lower limit
DriveVoltage Upper limit
DriveVoltage Lower limit
WakeUpTime Upper limit
WakeUpTime Lower limit
RealTime Upper limit
RealTime Lower limit
“PASS” or “FAIL”
CR Code (13)
LF Code (10)
___Until Here___
The measurement begins when the character string RUN is received.
5-4. Remote Terminal (represents the remote interface of the XT-310 interior portion)


Measurement begins when a low level is selected


Measurement ends when a low level is selected
In both cases, both start and stop button on the front panel initiate the same operation


Do not connect the GND to the GND of any other system


Turn this option on when the transformer to be measure is defective


Turn this option on when the transformer to be measure is of good quality


Turn this on when measurements are performed。


Connect the FG to the frame of any other system


The sink current is a maximum of 60mA
Supply voltage is a maximum of 300V

5-5. Probe Box PB3a

1 HV Connect to the measurement terminal of DUT by using the attached high-voltage connecting cable.
2 Return Connect to the low voltage terminal of DUT by using the attached return connecting cable.
The return terminal is not a GND. It is connected on the inside to the corona discharge detection circuit. Do not connect this to any other circuitry.
3 Probe Connect to the probe terminal of the XT-310 main unit using the attached probe cable.
4 F.GND Connect to the F.GND terminal of the XT-310 main unit using the attached F.GND connecting cable.
When high-voltage connection cable red or blue is used, the GND line of the cable is connected to F.GND.
6.Directions for use
6-1. Connection
Connect the probe terminal of the main unit and the probe terminal of the probe box using the probe cable. Connect the F.GND terminal of the main unit and the F.GND terminal of the probe box using the F.GND connecting cable. Connect the measuring table to F.GND terminal for noise prevention.
Connect the HV terminal of the probe box to the high-voltage side terminal of the DUT using the high-voltage connecting cable. Connect the Return terminal of the probe box to the low voltage side terminal of the DUT using the return connecting cable. The return terminal is not a GND. It is connected on the inside to the corona discharge detector circuit. Do not connect this to any other circuitry.
It is attached three kinds (white, red and blue) of high-voltage connecting cables.
Use it properly in accordance with the measurement frequency and DUT.
You must take impedance matching to provide a maximum output voltage.
3pF is the most suitable to 80kHz, and 60pF is the most suitable to 30kHz.Because the output inductance of PB3a is about 300mH.
Connect it with a white cable because the measurement of the corona discharge doesn’t have an error though a maximum output voltage doesn’t come out to 5kV when matching can’t be taken usually. When a high-voltage isn’t sufficient, a high-voltage connecting should use red or blue.
When matching can be taken, drive current becomes the smallest.
When for example the corona starting voltage of the magnet wire is measured with 30kHz, matching can be taken with not the blue cable but the white cable. Because the capacity of the twist line f =0.2mm, L= 300mm are about 50pF.
Also, 50pF is too big for measure it with 80kHz .The length of the magnet wire is set at less than 30mm, and you must move capacity to less than 5pF.
Think about the electrostatic capacity of DUT including the jig, and choose a measurement cable.
Be sure to connect it to F.GND (it is not return.) of PB3a because a GND wire (blue) comes out from red, the blue cable.
The oscilloscope, etc, can be connected to the monitor output on the rear panel.
Use Sync.Out for trigger input of the Oscilloscope. 1V/div for high voltage, 5V/div for corona / flashover, 1V/div for drive current, depending on the circuitry used, is suggested for the oscilloscope range. 5V/div is suggested for Drive voltage but depends on the transformer used.
6-2. Program Mode
Pressing the [Prog/End] key cycles the display screen to a mode where setting values are input.
First, the High Voltage settings display will appear.
The setting values are input in the following order: High Voltage upper / lower limit _ Flashover Upper Limit _ Corona upper limit _ Drive Current upper / lower limit _ Drive Voltage upper/lower limit _ Wakeup Time upper limit _ Real Time upper limit. The High Voltage display screen will return after the Real Time display screen. The values of Setting Entries and Current Settings are displayed. Press the numeric keys for the desired value and press [Enter]. For example, to enter the value 12.3, press [1] [2] [.] [3] and [Enter]. The entry is invalid and must be re-entered when [Enter] is pressed and values exceed the configurable range. To move passed the setting values without adjustment, simply press the [Enter] key. If Warning is displayed, re-enter the desired value.
To finish inputting setting values, press the [Prog/End] key to end.


Configurable Range
High Voltage Flashover Corona Drive
Drive Voltage Wakeup Time R.Time
0 – 5.00 kVrms 0 – 127 count 0 – 127 count 0 – 5.00 A 0 – 40.0 V 0 – 99.9 s 0 – 99.9 s
Note: Flashover and Corona count ends when setting values are exceeded. If the setting value 127 is entered (since 128 is non-existent) the count will not end.
Selecting 0.0 second for Real Time enables a limitless count. Use this for long-haul testing.
6-3. Function Mode
Function No. will be displayed when the [Func] key is pressed. Enter the function number here.
Press Enter after inputting the function no.
To quit Function Mode, press [Func] again.


Selecting Function No.1 Local / Remote

he current settings will be displayed in brackets.
Press [2] to choose Remote. When Remote is selected, the keyboard will not respond to anything other than the selection of Function No.1. This includes programming. However, the start and stop buttons can be used as normal.Press [1] to choose Local. When Local is selected, programming and other Function Numbers. are functional. Inspection conditions can not be overwritten while Remote is selected. Therefore, measurements in the production line can be used without concern.

Function No 4 sets the buzzer time will sound for when PASS and FAIL occurs.

The current settings will be displayed in brackets.
Input using the numerical and press [Enter] key.
Units are approximately 10ms. Selecting 75 will sound the buzzer for approximately 750ms.

Function No.5 indicates the high voltage peak hold

The current settings will be displayed in brackets.
Pressing [1] will peak hold ON. Pressing [2] will display OFF.

Function No.7 sets the operation of the buzzer when PASS and FAIL occur.

The current settings will be displayed in brackets.Pressing [1] will turn the buzzer OFF. Pressing [2] will turn the buzzer ON.Press [Enter] to end alterations.Press [1] or [2] to select whether the buzzer will sound when PASS occurs. Press [1] or [2] to select whether the buzzer will sound when FAIL occurs.

6-4. Measurements
Manual Mode

By selecting Manual mode using the mode selector, the test voltage can be changed by rotating Drive Adj. during the measurement process.Wakeup Time and Real Time don’t do STOP by the timer even if it is set up. STOP is done when it exceeds a lower limit.

Auto Mode

By selecting Auto mode using the mode selector, the High voltage will automatically increase until it reaches the lower limit +0.2kV, regardless of the Drive Adj. volume setting. When a limit over the lower limit of +0.2kV is reached, Real Time is examined and PASS or FAIL occurs.
Pressing the Start button will begin measurement. During measurements, the Active lamp lights up. When the lamp is lit, a high voltage is output via the HV terminal. Therefore, pleased be warned of the risk of electric shock.
Wait until the high voltage value has reached high the voltage lower limit of +0.2kV. During this period, the Wakeup Time is counted. Wakeup Time is display until it reaches 99.9 seconds. The timer will remain at 99.9 seconds even if a longer time frame has passed.
Wakeup Time count ends when high voltage exceeds the lower limit +0.2, at which point Real Time count begins. Measurements continue until a Real Time upper limit is reached.
When measurement ends within the settings range, the synthesized-test lamp will light up green, indicating PASS.
If the measurement value exceeds the settings range while testing, the test lamp will light up red, indicating FAIL, after which measurements end. The synthesised-test lamp will light red indicating FAIL. In addition, measurements can be terminated during tests by pressing the stop button. In this case, the synthesis test lamp will also light red, indicating FAIL.
The measurement value is output via the RS-232C terminal. This data can be transmitted using a Windows hyper-terminal.

7.Practical Examination Inspection
7-1. Inspecting the corona firing potential of an unknown transformer

Set the mode selector to Manual


Press the [Prog/End] key, select program mode and select the following settings. Input the setting values and press [Enter].When the settings have been correctly entered, press [Prog/End] to finish.

HV MAX 5.0kVrms
HV MIN 0.0kVrms
Flashover 0
Corona 0
Drive Current MAX 5.0Arms
Drive Current MIN 0.0Arms
Drive Voltage MAX 40.0V
Drive Voltage MIN 0.0V
Wakeup Time 2s
Real Time 2s



Adjust the Corona Rate switch to [1] and the Flashover Rate switch to [0].


Set the optional frequency.


Connect the oscilloscope if necessary.

CH1: Connect the high voltage monitor output
CH2: Connect the corona monitor output
Trigger Input: Connect the Sync. Out



Corona Firing Potential Measurement

First, reduce the voltage to minimum using the Drive Adj. volume and then press the start button. (Pressing the Start button with voltage increased, Flashover may occur at once.)
Quietly raising the Drive Adj. measure the HV rms when the corona count begins.
Terminate measurement when flashover occurs during the monitoring and increasing of voltage. Take readings of the voltage right before the voltage decrease that occurs with flashover. It is convenient to indicate the peak hold using Function No.5.


Press the Stop button to end measurements.


7-2. Confirming Corona Discharge by Visual Observation


To continue measurement even if corona discharge occurs, use the corona setting value 127.


For other setting values, follow the settings in section 7-1-2.


A weak light is produced at places of corona discharge, which can be visually confirmed by lowering room lighting.


7-3. Inspecting the presence of corona / flashover using Auto mode at 2.5kVrms

Set the mode selector to ‘Auto’


Adjust the Corona Rate switch and Flashover Rate switch to 1.


Setting the frequency (confirm using the product)


Input the setting values as follows

HV MAX 3.5kVrms
MIN 2.3kVrms The test voltage is +0.2kV
Flashover MAX 0 Stops at 1 count
Corona MAX 0 Stops at 1 count
Drive Current MAX 5.0 A No particular limit
MIN 0.0 A
Drive Voltage MAX 40.0 V No particular limit
MIN 0.0 V
Wakeup Time MAX 2.0 s Short detection
Real Time MAX 2.0 s High voltage test time

In the above case, takt time is 3 seconds

8.Explanation of Setting Values
8-1. High Voltage (HV MAX)
Even a good quality coil will be destroyed if voltage increases too greatly. To prevent this from happening, preset HV MAX. This results in an automatic stop if the voltage volume is over-increased and HV MAX is exceeded.
HV is displayed in kVrms. A successful test will result if within the HV MIN and HV MAX range.
Set the HV MAX at least 0.2kV higher than the test voltage. In other words, set it to HV MAX>=HVMIN+0.4kV
8-2. High Voltage (HV MIN)
The test voltage while in Auto Mode should be HV MIN+0.2kV. Set the HV MIN to minus 0.2kV of the desired test voltage.
If when using a poor quality coil, voltage falls short of HV MIN+0.2, High voltage tests (Real Time) are not possible, and so Wakeup Time is counted. If while in Auto Mode the Wakeup Time is set to approx 2 seconds, and this time is exceeded, poor quality measurements will be taken. Additionally, poor HV measurements occur when spark discharge occurs and HV falls below HV MIN after the test voltage has been achieved. (A shorted coil will produce corrupt results) However, when such testing is not necessary or when Corona discharge is detected in Manual Mode while increasing and decreasing HV, etc, select HV MIN=0.
8-3. Flashover (Spark Discharge)
Setting Flashover to MAX=0 results in a poor test and ends when 0 is exceeded (when =1 is reached). To force testing to continue, even when spark discharge occurs, set it to 127, as internal count 128 is non-existent.
8-4. Corona
Setting Corona to MAX=0 results in a poor test and ends when 0 is exceeded (when =1 is reached). To force testing to continue, even when corona discharge occurs, set it to 127, as internal count 128 is non-existent.
8-5. Drive Current MAX
There will hardly be a flow of current if the coil is disconnected, and large current will flow if there is a layer short.
Therefore, if the current of a normal coil is set to approximately _ to 2 times as much, you should be able to avoid using a dysfunctional coil.
Also, please note that the current will increase even if the test frequency is too high or too low.
8-6. Drive Current MIN
An appropriate current flows when a good quality coil has been connected. However, when the bad jig connection, the current will cease flowing. Therefore, setting MIN to _ the current of a good quality coil, makes detection of a poor connection (or the breakdown of a primary wire) possible.
8-7. Drive Voltage MAX, MIN
This should have a deep correlation to HV, but it is thought best not to set it too harshly. Set it to approximately _ to 2 times as much as that of a good quality coil. It is believed that this can be used for the analysis of defective coils.
8-8. Wakeup Time
Wakeup Time is the time from test start to high voltage up to test voltage. (HV MIN+0.2kV)
When the set time is passed in Auto Mode, poor measurements will be taken due to insufficient voltage. Ordinarily, this should be set to 1.0 – 2.0 seconds.
In Manual Mode, Wakeup Time settings are bypassed.
8-9. Real Time
After exceeding the set HV MIN of +0.2V, the elapsed electric strength test time will be displayed. If there are no abnormalities when the set time approaches, a successful measurement are taken and the test ends.
Please note that in cases where the setting value is 0.0 seconds, the test will run continuously. When Flashover, etc, occurs, the test will end. Please use a separate timer for the elapsed time. A separate timer is also necessary for used for ageing tests, etc. During HV generation, BUSY will be output on the Remote terminal. Automatic measurement of the time of failure during a long ageing test can be taken by switching the outer timer of the BUSY signal ON or OFF.
In Manual Mode, continuous operation will occur, regardless of Real Time settings.
9.Notes on the Measuring Device Settings
Corona discharge is a faint type of discharge. In order to detect corona discharge, you must detect the faint pulse signal generated by corona discharge. If the external noise level is big, the count may be affected. Therefore, to avoid this, please be aware of the follower points.
9-1 Frame Grounding the Measuring Table
Connect the XT-310 F.GND to the measuring table if it is made of is metal. Additionally, it is best to connect it to the grounded earth wire. However, if this is not possible, connect it to the iron frame of the building. If the measuring table is not made of metal, lay a metal board approx 1m x 1m in diameter (an aluminium board is ok) on the measuring table, and lay a mat, etc, on top of that. Connect the metal board to the F.GND of the XT-310. Place the XT-310 main unit, probe box, and all measuring table tools, on top of the metal board.
9-2 Shortening the Connecting Cables
Shorten the cable so there are no loops to avoid noise interference.
Provide ample space between the HV wiring and other wires or metals. In particular, please note the insulation of jigs.

9-3 Confirming that noise is being picked up.
Carry out a continuous operation using a voltage with which corona discharge does not occur for approx 30 minutes. If the corona discharge count is 0, noise is not being picked up and the device can be used without the worry of noise interference.
If the corona discharge count is not 0, take measures to avoid noise interference as best possible. (Note: Real Time will continuously run when the count is 0. In this case, measure times with an external timer.)
9-4 Using the device even with noise interference
Corona discharge occurs episodically (at least a count of 5 every second). However, it is natural for external noise to occur irregularly. For example, in cases where the external noise count is 10 over a 30 minute period, on average, the frequency is a 1 count every 180 seconds. With the test time as 2 seconds:
External Noise 0.01 count
Corona Discharge count 10-20 count
Therefore, if the limit of corona discharge is set to between a 1 – 3 count, noise will not interfere with tests, and defective good producing corona discharge can be filtered out.
9-5 Determining the Noise Source
If the noise source is near the device, it is more difficult to take countermeasures. Confirm that devices near by are not the source of noise by turning the power ON and OFF. If found, investigate whether the noise source can be shut off. There may be little effect from using an alternate power supply outlet.