TKLVF-30kV ultra-low frequency AC high voltage test device

A series of ultra-low frequency products and their selection

1Naming instructions

××—30/1.1

Rated load capacitance, unit: μ F

Rated peak output voltage, in kV

Product letter code

2. Table 1 of ultra-low frequency series products

3Select appropriate product specifications based on the participants' orientation.

When in use, the capacitance of the test sample shall not exceed the rated capacitance of the instrument. If the capacitance of the test sample is too small, it will affect the output waveform. If it is less than 0.05 μ F, the instrument will not be able to output normally. At this time, a capacitor with 0.05 μ F (provided by our company) can be connected in parallel to assist in output. Here are the capacitance values of some devices for users' reference.

Single relative electrical capacity of different generators Table 2

Table 3: Capacity (μ F/km) of Cross linked Polyethylene Insulated Single Core Power Cables

4. Estimation method for sample current:

　　　　Calculation formula: I=2 π fCU

TKLVF-30kV ultra-low frequency AC high voltage test device

Principle of ultra-low frequency insulation withstand voltage test

The ultra-low frequency insulation withstand voltage test is actually an alternative method to the power frequency withstand voltage test. We know that when conducting power frequency withstand voltage tests on large generators, cables, and other test samples, large capacity test transformers or resonant transformers are required due to the large capacitance of their insulation layers. These huge devices are not only bulky and expensive, but also very inconvenient to use. In order to solve this contradiction, the power department has adopted reducing the testing frequency, thereby reducing the capacity of the testing power supply. From years of theoretical and practical experience both domestically and internationally, it has been proven that replacing the power frequency withstand voltage test with a 0.1Hz ultra-low frequency withstand voltage test not only achieves the same equivalence, but also greatly reduces the size and weight of the equipment. In theory, the capacity is about one fifth of the power frequency, and the operation is simple, making it more efficient compared to the power frequency test. That's why developed countries generally adopt this method. The country has formulated the industry standard for the ultra-low frequency (0.1Hz) withstand voltage test method of 35kV and below cross-linked polyethylene insulated power cables. This method is being promoted in our country, and this instrument has been developed according to the needs of our country. It can be widely used in AC voltage withstand tests for cables and large high-voltage rotating motors.

Three product introductions

This product combines modern digital frequency conversion technology and adopts microcomputer control for automatic boosting, lowering, measurement, and protection. Due to full electronicization, it has a small size, light weight, large screen LCD display, clear and intuitive display, and can display output waveforms and print test reports. The design indicators * comply with the power industry standard of "General Technical Conditions for Power Equipment Testing Instruments, Part 4: General Technical Conditions for Ultra Low Frequency High Voltage Generators", and are very convenient to use. Nowadays, both domestically and internationally, mechanical methods are used for modulation and demodulation to generate ultra-low frequency signals, resulting in non-standard sine wave waveforms, large measurement errors, spark discharge in the high-voltage part, bulky equipment, and high-power high-voltage resistors for discharge shaping in the second and fourth quadrants of the sine wave. Therefore, the overall power consumption of the equipment is relatively high. This product can overcome these shortcomings and has the following characteristics:

1Ultra low frequency with rated voltage less than or equal to 50kV adopts a single connection structure (one booster); Ultra low frequencies greater than 50kV adopt a series structure (two boosters connected in series), which greatly reduces the overall weight and enhances the carrying capacity. Moreover, the two boosters can be used separately as low voltage level ultra-low frequencies.

2、The current, voltage, and waveform data are all directly sampled from the high-voltage side, so the data is accurate.

3、Equipped with overvoltage protection function, when the output exceeds the set voltage limit value, the instrument will shut down for protection, with an action time of less than 20ms.

4、Equipped with overcurrent protection function: designed with high and low voltage dual protection, the high voltage side can be shut down for protection according to the set value; When the current on the low-voltage side exceeds the rated current, a shutdown protection will be implemented, with an action time of less than 20ms.

5、The high-voltage output protection resistor is designed inside the boost body, so there is no need to connect another protection resistor externally.

　　6Due to the use of high and low voltage closed-loop negative feedback control circuits, there is no capacitance rise effect in the output.

TKLVF-30kV ultra-low frequency AC high voltage test device

Four technical parameters

1Rated output voltage: refer to Table 1

2Output frequency: 0.1Hz, 0.05Hz, 0.02Hz

3Load capacity: 0.1Hz maximum 1.1 μ F

0.05Hz zui 大2.2μF

0.02Hz zui 大5.5μF

4Measurement accuracy: 3%

5Voltage positive and negative peak error: ≤ 3%

6Voltage waveform distortion: ≤ 5%

7Usage conditions: indoor and outdoor; Temperature: -10 ℃∽+40 ℃; Humidity: ≤ 85% RH

8Power fuse: refer to Table 1

9Power supply: frequency 50Hz, voltage 220V ± 5%.