High voltage withstａnd test of electrical equipment is one of the most important items specified in insulation preventive test.

The withstａnd voltage test can be divided into ac withstａnd voltage test and dc withstａnd voltage test. The ac withstａnd voltage test can be divided into power frequency, frequency conversion and 0.1hz ultra-low frequency test technology, of which 0.1hz ultra-low frequency technology is the latest technology recommended by the current international electrotechnical commission.

Our company's new generation of VLF Test Equipment equipment is the core product independently developed with the latest American technology. VLF Test Equipment adopts 7-inch touch screen, the latest arm7 single chip microcomputer, high-speed ad acquisition circuit, and is equipped with background management software. VLF Test Equipment overcomes many shortcomings of domestic similar products.Meanwhile, its cost performance is much higher than that of similar imported products. VLF Test Equipment is especially suitable for withstａnd voltage test of electrical equipment with large insulation equivalent capacitance (such as power cable, power capacitor, large and medium-sized generator and motor, etc.)

Advanced technology: digital frequency conversion technology, microcomputer control, pressure rise, pressure reduction, measurement, protection, etc

The test process is fully automated.

Easy to operate: simple wiring, fool operation.

Comprehensive protection: multiple protection (over-voltage protection, over- current protection at high and low voltage sides), rapid action (when acting)

Room ≤ 10ms), the instrument is safe and reliable.

Safety and reliability: the controller is connected with the low voltage of the high voltage generator, with photoelectric control, safe and reliable use.

The high and low voltage closed-loop negative feedback control circuit is adopted, and the output has no capacity rise effect.

Complete configuration: capacitive touch screen, LCD Chinese character display, automatic storage, automatic printing.

Large test range: 0.1Hz, 0.05Hz and 0.02hz multi frequency selection, large test range.

Small volume and light weight: it is very convenient for outdoor operation.

VLF Test Equipment output wiring method

Wiring instructions: connect the control output special line, high voltage output special line and grounding wire equipped with the product according to the method shown in Figure 3. The power cord of the power socket is connected to the AC of 220V / 50Hz/60HZ. (Input voltage can be customized)

1. Some setting and boosting interface of the vlf tester

Below controller interface indicates that the voltage is boosting

Below controller interface prompts to stop the test

Below is the over current protection prompted by controller

More operation instructions ,pls kindly contact the supplier.

1. Upper computer background management software

This VLF Test Equipment is equipped with VLF super low frequency and high voltage generator upper computer background management software, as shown The software supports Windows XP / 2000 / 2007 and other operating systems. The software can be installed on the computer and connected with the USB of the controller through the USB connection line. All the operation functions of the controller can be operated on the software, such as setting parameters,

starting the boosting test, saving historical data, etc.

I. Power cable withstａnd voltage test method

1. Disconnect all electrical equipment connected to the tested cable.

2. Use a megger to test the insulation parameters of each phase of the cable, and carry out the ultra-low frequency withstａnd voltage test only after the test is qualified.

3. Set the test voltage value: Umax = 3uo, where uo is the rated phase voltage of the cable.

Example 1: cable parameter: the rated line voltage is 10kV, and the rated phase voltage uo = 6kV, so the test voltage setting value is:

Umax = 3uo = 18kV

See Table 1 for the setting value of 0.1Hz ultra-low frequency test voltage of various rubber and plastic insulated power cables.

Table 1 0.1Hz ultra-low frequency test voltage and time of various rubber plastic insulated power cables.

Note: UN is the rated voltage of the cable, and uo is the phase voltage of the cable.

1. Test time: 60 minutes for handover test and 15 minutes for preventive test.

2. Setting current value of overcurrent protection:

Estimation method of capacitive current (or leakage current) of ultra-low frequency withstａnd voltage test article:

Io=2πfCU=2×3.14×0.1CU(mA)… (formula 1)

C is the electric capacity of the cable to the ground, unit: UF; u is the effective value of the test voltage, unit: kV.

Example 2: a 10KV (UN = 10kV, uo = 8.7kv) cable is 4km long, with a single phase to ground capacitance of 0.21uf/km and 0.1Hz super

If the low frequency test voltage is 26kv (peak value), the leakage current is approximately:

Io=2πfCU=2×3.14×0.1CU=0.628×0.21×4×26/ 2 =9.69（mA）

Setting current value of overcurrent protection: I=kIo…(formula 2)