HZDP-30K Very Low Frequency Cable Testing VLF High Voltage Generator

Contents I. Ultra-Low Frequency Products and Selection of It …………………3 II. Theory of Ultra-Low Frequency Dielectric Strength Test…………4 III. Products Introduction …………………………………………………4 IV. Technical Parameter……………………………………………………5 V. Instrument Structure ……………………………………………………6 VI. How To Operation...

Send InquiryChat Now
Product Details

HZDP-30K Very Low Frequency Cable Testing VLF High Voltage Generator


Vlf Low Frequency Hipot tester

1.Fully discharge the tested object with discharge rod before starting up, (the discharge rod using method is: first discharge with the current-limiting discharge end, then ground terminal). Ultra low frequency connection method with two booster:When using the booster I alone (test voltage is 30 KV or less), instrument control output I must be connected to booster I, don't connect control output II. When the booster I and booster II are used in series (test voltage is 80 KV or less), instrument control output I must be connected to booster I, and instrument control output II must be connected to booster II, absolutely not inversely connection! Otherwise the instrument or tested object will be damaged.
2.Please use the STOP button and discharge by rod then shut down the power if you need to discontinue the machines which in the high pressure conditions.Otherwise it will damage the instrument!
3.Please operation it according to the screen instructions.
4.It is a normal phenomenon to see small amount of oil spill after boosting the pressure because the insulating oil in the booster is full, besides, it will not affect your use.
5.When carrying out 10KV cable test, one-phase test is strongly suggested. The voltage shall be 18KV and the frequency shall be 0.1Hz、0.05Hz、0.02Hz. The manual said load capacity is the theoretical value, the scene 10KV cable length can reach 3-8 km.
6.When carrying out 35KV cable test, one-phase test is strongly suggested. Voltage is set to 60KV (general requirements)-78KV (according to the rules needed) and the frequency is set to 0.1Hz, 0.05Hz, and 0.02Hz. The manual said load capacity is the theoretical value, the scene 35KV cable length can reach 3-5 km.
7.In case the cable is too short(less than 500 meters), the capacitance of the test object is smaller than 0.1μF and the pressure cannot be normally boosted, please connect 0.1μF high-voltage capacitance in parallel way.
8.Keep high-voltage terminals nylon spin by the above numbers to the corresponding nylon seat, high-voltage lines to ensure good contact , no contact is good , it will cause a discharge , burned the high side . When nylon terminals tightened, pay attention to the intensity, excessive tightening may damage the nylon terminals.
9.If it is equipped with two booster ultra low frequency:When the test voltage is 30 KV or less, at this point it needs booster I to boost only, not connecting booster II. Booster number can also be set to I+II, at this point booster I and II boost in series; When test voltage is more than 30 KV, booster I and II must be used in series, see operating instructions in instruction book for connecting methods.
10.Laboratory examination timing, because DC voltage divider sampling speed is very slow, need to see more than ten cycle, in order to see the peak positive and negative voltage, the peak is the actual output voltage value.
11.Control output line connected to the booster side air plugs need to be rotated downward pressure to pull out!
12.Recommend the use of AC power supply of 220V: if you have to use a generator to supply power, because the 0.1Hz ultra low frequency is based on the power input frequency modulation, have higher requirements, to the generator requirements are: frequency 50Hz, voltage 220V + 5%, power is greater than 5KW, the special requirements of the generator output frequency stability, frequency changes with the load (the best use of digital frequency conversion generator), and not less than the resistive 800W load at the output end of the generator are connected with a power (such as electric stove etc.), in order to stabilize the generator speed, if the frequency is not stable, certainly not normal booster. In the whole process of increasing pressure, resistance load must use of continuous work, cannot use will automatically cut off the load resistance (such as electric kettle, electric furnace, temperature control switch after the water is boiling or temperature is reached, will be cut off automatically load), otherwise will seriously damage the instrument!!!
13.When turning on the power supply lamp does not light or no screen display, the insurance tube may be burned, for a safety tube is good, we are equipped with 10 insurance tube standby.
Warning: in the cable voltage withstand test, must be the core wire and the insulating layer of the physical separation, not with the other items covered in the above, otherwise it will cause the high voltage discharge, damage the instrument!!!

0.1Hz Ultra-Low Frequency High Voltage Generator

I.Ultra-Low Frequency Products and Selection of It

1、0.1Hz -30KV Ultra-Low Frequency High Voltage Generator

Table 1


Rated Voltages

Load capacity






(peak )



Control :6㎏

Body Boost :30㎏

10KV Cables、Generator



2、How to choose the suitable products for test
Please make sure that the capacitance of test products is below the instrument rated capacitance. The waveform will be influence if the capacitance of test products is too small and the instrument can not normally output when it below 0.05µF. 0.1µF capacitor in parallel to auxiliary output. Below is capacitance of some instrument for your reference.
Single relatively power capacity of different Generator  
Table 2

Thermal Power


Generator capacitance









Single relatively

power capacity(µF)








Power capacitance of single-core XLPE insulated cable (µF/km)

Table 3

Capacity µF/Km

Voltage (kV)


























area (cm²)












4、Products test current estimation method
Formula :I=2π  fCU
II.Theory of Ultra-Low Frequency Dielectric Strength Test
Ultra-Low Frequency Dielectric Strength Test is the alternative way for power frequency voltage withstand test. as we know , it is needed huge capacity testing transformer or a resonant transformer for power frequency voltage withstand test to large generator ,cables etc due to larger electrical capacity of insulating layer . The huge equipment not only bulky but also expensive and not suitable for use. The electricity sector makes some test to solve the problems. according to theory and test result from domestic and overseas , 0.1Hz ultra-low frequency voltage withstand test can solve this problems and the advantage is not only got same test results but also the instrument dimensions is small and considerably reduced the weight of it . The capacity of it is 1/500 of tradition way. Greatly simplify testing procedures, That is why commonly used in the developed countries, china ‘s ministry of electric power entrust Wuhan high voltage research institute to drafting “  35Kv and below XLPE insulated power cable ultra-low frequency (0.1Hz) voltage withstand test methods ‘for promoting this approach. The instrument is developed according to China's made of this need. It can be widely used in cable, large-scale high-pressure rotary motor, power capacitors into AC voltage withstand test.
III.Products Introduction
This product combines the advanced technology of modern digital conversion, fully computer control, automated boost, buck, measurement and protection. human intervention can cared out during the automatic step-up process , mains advantage includes fully electronic ,small sizes and light weight , large-screen LCD ( clear and intuitive ) , printer output test report , easy to use . designed to fully meet the power industry standards .mechanical approach are widely use for modulation and demodulation ultra-low-frequency signals but no standard sine wave , some error of measuring and spark discharge in high-pressure part etc, the products can overcome the shortcoming of above and the following features need to indicate in particular:
Data of current and voltage are obtained directly through the sampling of high-pressure side and it is true and accurate. Over-voltage protection: the instrument will shut down to protection within 20 ms when the output voltage is exceeding limiting values of setting.
Over-current protection: design for dual protection of high and low voltage, downtime protection can be accurately set in high-pressure side. Shut down to protection times is within 20 ms when the current of low-voltage sides exceeds reacted current.
High-voltage output protection resistor design in the body boost and it is no need to additional outside resistor.
Closed-loop negative feedback control circuit of high and low voltage.
IV.Technical Parameter
1、output rated voltage , Table 1 for reference
2、output frequency :0.1Hz、0.05Hz、0.02Hz。
3、loading capability : Table 1 for reference
0.1 Hz maximum 1.1µF
0.05 Hz maximum 2.2µF
0.02 Hz maximum 5.5µF
4、accuracy :± (3% of full scale +0.5 KV)
5、voltage waveform distortion :≤5%
6、condition of use : indoor, outdoor; temperature : -10℃∽+40℃;humidity :≤85%RH
7、power supply :AC50 Hz,220V ±5%
8、power fuse : Table 1 for reference

V.Instrument Structure
1、control panel diagram


Table 1

(1)“ground ”:ground terminal ,used link with the earth .
(2)“control output”:output multi-core sockets , used with input multi-core socket of body boost.
(3)“contrast ”:contrast adjustment for LCD
(4)“Function Key ”:display prompt bar corresponds to location cue
(5)“AC220V”:power input , fuse insider
(6)“power switch ”:indicator insider.
(7)“printer ”:for test report
(8)“LCD screen ”:display test data .
2、body boost diagram


Table 2
VI.How To Operation
1、connection method


Table 3 (connection diagram )
With this product is equipped with two dedicated random lines and you can connection according to Table 3, power with AC 50Hz/220V.
2、operation sequence
(1) power on : please noted that the test products will be fully discharge when power on the machines and press on the stop button first when the machines is on the boost procedure then use power switch .
The instrument will enter into Table 4 interface restriction when power on the machine after you have finished connection it , please make sure the instrument is power off when you connection or stitches or not use the instrument .please first checking the fuse of the power outlet if no display in the screen .
(2) Defined parameter settings


主菜单:Main menu

试验频率设定:Setting test frequency
试验电压设定:Setting test voltage
限制电压设定:Setting limit voltage
限制电流设定:Setting limit current
试验时间设定:Setting test times
启动试验电压:Start test voltage
Table 4(interface restriction )
You can pre-setting the test frequency, voltage and protection values of exceed pressure in the high pressure sides, protection values of exceed voltage, test times etc according to test needed in the interface restriction of Table 4 Three options for frequency : 0.1、0.05、0.02 . it is the instrument output frequency and unit is Hz The test voltage is from 10KV to rated values (please do not setting the test voltage below 10KV). The instrument will not boost anymore when it is on the setting values and maintains amplitude output of sine wave in this peaking value.
The protection values of voltage are from 0 to rated value and unit is kV. It is indicated the peaking values of test products .the instrument will automotive shut down the output when the voltage is exceed the setting. Under normal circumstances, voltage protection values are set higher than the test voltage 4KV.
The protection values of current are from 0 to rated value and unit is mA. It is indicated the current peaking values of test products .the instrument will automotive shut down the output when the current is exceed the setting.
Times setting is from 0-60 minutes and it is indicated the test times, unit is minutes.
Above voltage, currency is peaking values, test data of instrument Display and voltage, currency data in the test report is all peaking Values.
Please move the cursor to “start test voltage “and confirmed it then enter into below Table 5 boost interface.


正在升压中请稍后:Boost now,wait for a minutes
计时: Timing
Table 5(boost )
Automotive boost The instrument enters into boost status when finished self checking success. It will take some times to make the voltage reach the setting values. The instrument will shut down 

voltage output and enter into start interface if you press the stop button when boost procedure.
Table 6 will appear in the interface when the boost values is close to setting values


正在升压中请稍后:Boost now,wait for a minutes

电压:Voltage                电流:Current
按上下键微调电压:Voltage adjust by press on up and down keys
按确定键启动计时:Start timing by press on confirm button
Table 6
Please press on the “on and off ”;button for 1 second and adjust the voltage then press the confirm button , Figure 7 appears, instrument start time,the instrument will start timing and the test report will print out when it is finished . Back to the start screen, after discharge shutdown before the start of the next measurement.


Table 7

Another un-normal stop is over-voltage protection shutdown, over current shutdown. The tip interface will appear when the instrument stops. You can re-set the voltage or current to start next measurement.
VII.Ultra-Low Frequency Strength Test of Cables
1、please make sure that all the connection equipment of test products is divest from the cable of test products.
2、separately cable insulation resistance test by 10000V Megger test items and recorded the test values.
3、test voltage peaking values :Umax=3Uo, Uo is rated working voltage between cable conductor-to-ground or metal shield ,for examples, rated voltage 10KV cable, single-phase rated voltage
voltage peaking values of test is :Umax=3Uo
4、test times :3 minutes
5、test separately . Cable capacitor values of test products are within the instrument loading capability. Pressure test can operation at the same times by cable three–phase lines in parallel.
6、connecting the instrument with the test products’ cable by special flexible connecting cable ( accessory ) according to Table 8. Power on the instrument and finished setting the test frequency , times ,voltage, over-voltage protection values in the high-pressure sides, over current protection values then start boost test .please pay attention to the high-pressure feedback circuit and checking if there are un-normal sounds in the cable of test products .you can record test times and test voltage when boost to test voltage .
7、the instrument will showdown automotive if the test times finished and the products pass the pressure test if there are disruptive discharge happened .
8、please stop the instrument boost ,power off the machines if there are some problems such as current un-normal enlarge ,voltage instability , unusual smell , smoke or noise or flash branding phenomena in the test products cables happened in the boost and pressure procedure .then checking it . The pressure test is failure if it is by the cable insulation weak part of test items. You can retest it if you confirm it is by the humidity or dirty surface.
9、please do the pressure test again if the instrument is over current protection by the reasons except the cable insulation defects.


Table 8 

measurement of single-phase connection diagram
VIII.Ultra-Low Frequency Strength Test of Large Scales High Voltage Generator
The Generator test method is similar with the above cable test and below is the difference:
1、the test can be carry out during the transfer of major repairs ,partial replacement of winding and other conventional test . 0.1Hz Ultra-Low Frequency High Voltage Generator is more effective to test generator end insulation defects than other instrument. the reason is that in frequency voltage ,due to outflow from the bar capacitive current flowing through the insulation in the outside layer of the semiconductor anti-corona caused by a larger voltage drop, thereby insulating rod end of the line voltage decreases the pressure on ; while in the ultra-low frequency cases, this capacitor current is greatly reduced, and the semiconductor layer on the anti-corona voltage drop has been greatly reduced, it ends on a higher voltage insulation, easy to find flaws.
2、connecting method : test separately , subjects were similar pressure ,Table 9 for reference .
3、test voltage peaking values is calculated below ,
Umax : peaking values (kV)of 0.1Hz test voltage
β:equivalent coefficient in 1HZ AND 50HZ, we take 1.2 according to the requirement of our procedures .
K:general speaking 1.3∽1.5   usually 1.5
Uo :rated voltage(kV) of stator winding of generator
For examples: Generator rated voltage is 13.8 kV,
Ultra-Low Frequency test voltage peaking values :
4、test times is according to instruction ,
5、the cable insulation pressure test is pass if there are no unusual sound ,smell , smoking or instability data display etc during the press test . Please fully pay attention the insulation surface status for better understand of insulation conditions.
Especially for air-cooled unto, Experience that can discover devices by monitoring the appearance does not reflect the generator insulation is not a normal phenomenon, such as the surface of corona discharge


Table 9 measurement of the stator of a connected line graph
IX.Ultra-Low Frequency Strength Test of Power Capacitor
Test operation method is similar with the above, Table 10 is the connecting way for you reference, please setting the test voltage and times according to the instruction.
Output control        High voltage output



control          booster  
Table 10   measuring capacitor wiring diagram 
1、The booster used in the instrument is not allowed for another use.
2、Please contact the factory for repairs if the instrument malfunction
and do not open it by yourself .
3、Before stitches , please fully discharge the test products by
discharge rod after power off the instrument .
4、Please fully discharge the test products by discharge rod before
power on the instruments .
5、Please fully discharge the test products by discharge rod before
press on boost button each times .
XI.Packing List  
1、0.1Hz/30KV control box (1pcs)
0.1Hz/30KV booster (1pcs)
0.1Hz/30KV shunt capacitor (1pcs)
30KV high-voltage output lines (1pcs)
Shunt capacitance high-voltage cables (1pcs)
Special control cables (1pcs)
Power lines (1pcs)
Ground wire (1pcs)
9、Discharge Rod (1pcs)
10、Power fuse (10pcs)
11、Printing paper (1pcs)
12、Instruction manual (1pcs)
13、Factory certification (1pcs)
14、Factory inspection report (1pcs)

Related Products