Test principle

Ultra-low frequency insulation withstand voltage test is actually an alternative to power frequency withstand voltage test.We know that in large-scale generators, cables and other test products for power frequency withstand voltage test, because of their insulation layer presents a large Capacitance, so the need for a large capacity test transformer or resonant transformer. Such a huge number of equipment, not only bulky, high cost, and the use of very inconvenient.In order to solve this contradiction, the power sector to reduce the test frequency, thereby reducing the test The capacity of the power supply from domestic and foreign years of theory and practice proved that the use of 0.1Hz ultra-low frequency withstand voltage test instead of frequency withstand voltage test, not only have the same equivalent, and the equipment greatly reduced the size of the weight greatly reduced , The theoretical capacity of about one-fifth of the frequency of the test program greatly reduced, compared with the power frequency test more superiority.This is why the developed countries generally use this method reasons.China's Ministry of Electricity to Commissioned the Wuhan High Voltage Research Institute drafted the "35kV and below XLPE insulated power cable ultra-low frequency (0.1Hz) pressure test method" industry standards.China is promoting this method, the instrument is based on the needs of our development Can be widely used in cable, large high-voltage rotating electrical machines, power capacitors in the exchange of pressure test.

Product Introduction

This product combines modern digital frequency conversion advanced technology, the use of computer control, boost, buck, measurement, protection and complete automation, and in the automatic boost process can be manual intervention due to full electronic, so small size, light weight Screen LCD display, clear and intuitive, the printer output test report. Design indicators in full compliance with "power equipment dedicated test equipment general technical conditions, Part 4: ultra-low frequency high-voltage generator general technical conditions" power industry standards, the use of very convenient now domestic and foreign The use of mechanical methods for modulation and demodulation to produce ultra-low frequency signal, so there is a sine wave waveform is not standard, measurement error, high-voltage part of the spark discharge, equipment bulky, and sine wave two or four quadrants also need high power Resistance of the discharge plastic, so the overall power consumption of the device.This product can overcome these shortcomings, in addition, there are the following characteristics need special instructions:

★ current, voltage data are obtained directly through the high-side sampling, so the data is true and accurate.

★ overvoltage protection: When the output exceeds the set pressure limit, the instrument will stop protection, action time is less than 20 ms.

★ over-current protection: designed for high and low voltage double protection, high pressure side can be set by the value of accurate shutdown protection; low side of the current exceeds the rated current will be shut down protection, action time is less than 20 ms.

★ high-voltage output protection resistor designed in the boost body, so no need to protect the outside of the other resistance.

★ As a result of the use of high and low voltage closed-loop negative feedback control circuit, so the output capacity without capacity.

Product parameters

Ultra-low frequency products Table 1