【overview】In addition to the long-term operation under rated voltage, the power generation, supply and consumption equipment in the power system must have the insulation strength under overvoltage. Overvoltage refers to the voltage rise that exceeds the normal operating voltage, which is the damage of electrical equipment or protective equipment. In all kinds of power system accidents, a large part is caused by the insulation damage of equipment caused by overvoltage. When the insulation is defective, if it is not found and eliminated in time, it will eventually lead to equipment damage and power failure.

In addition to the long-term operation under rated voltage, the power generation, supply and consumption equipment in the power system must have the insulation strength under overvoltage. Overvoltage refers to the voltage rise that exceeds the normal operating voltage, which is the damage of electrical equipment or protective equipment. In all kinds of power system accidents, a large part is caused by the insulation damage of equipment caused by overvoltage. When the insulation is defective, if it is not found and eliminated in time, it will eventually lead to equipment damage and power failure. Affect the production and people's living. The purpose of the high-voltage test is to rely on certain means to rely on the relevant testing equipment to use analog methods to test the reliability of the insulation performance of electrical high-voltage test equipment to provide reliable and powerful data for safe generation, supply and use of electricity.

The insulation defects of electrical high-voltage test equipment are roughly divided into two categories: one is the overall defects such as insulation aging, deterioration, moisture and dirt, which completely reduce the insulation performance; the other is local defects, such as: local insulation Damage, moisture and dirt make the insulation performance decline. Any kind of insulation defect can be detected by high voltage prevention test. Therefore, electrical equipment in the operation of a certain period of time to carry out regular testing and testing. This is an important measure to ensure the safe operation of electrical equipment in China. Through the high voltage test to master the electrical equipment insulation change law timely detection of defects. Corresponding maintenance and overhaul measures shall be taken to avoid the breakdown of electrical equipment insulation under the action of rated voltage and overvoltage and cause power failure accidents.

The insulation prevention test of electrical high voltage test equipment is generally divided into two types: the characteristic test of insulation performance and the strength test. The former is also known as non-destructive testing, which refers to the use of low voltage or other methods that do not damage the insulation. Tests on various characteristics of equipment insulation from different angles. Such as insulation resistance test, leakage current test and media loss factor test. The latter, also known as destructive test, is a withstand voltage test for the insulation of electrical equipment under the action of higher voltage. Such as DC withstand voltage test and AC withstand voltage test. High voltage test is an important measure to judge the safety of electrical equipment in operation.

Therefore, in order to ensure the quality and reliability of the equipment, the experimenter has the following requirements:

(I) Carefully and Carefully Do the Insulation Preventive Test of Electrical High Voltage Test Equipment

Q/CSC10007--2004 the test items specified in the Preventive Test Regulations for Electrical Equipment. The cycle and standard are the accumulation and summary of the experience of China's power industry for more than half a century. It has important guiding significance for preventive testing, and must be carefully studied and implemented. The selection of test items should be as comprehensive as possible to prevent equipment with serious insulation defects from being put into operation. Due to the different operating environments of electrical equipment, the deterioration speed of insulation is also different. For example: regular operation of the circuit breaker to be tested annually; normal operation of the transformer in 5 to 10 years to be tested, the generator winding due to the impact of vibration in operation, must also be an annual AC withstand voltage test.

(II) should have high analytical ability

The test results are the basis of analysis and judgment, the correct use of test standards to judge the advantages and disadvantages of insulation, to estimate the development trend and severity of insulation defects. When the test results of individual projects do not meet the requirements of the regulations or there is no standard for this equipment to refer to, the following skills should be possessed:

1. It is necessary to go deep into the maintenance site to understand what defects are in the maintenance process of this equipment, how many have been dealt with, and what have not been eliminated, and at the same time understand the load changes of the equipment during operation. Temperature and environmental information for judgment.

2. Compare the test results of previous years and understand the operation of this year to demonstrate your own judgment results.

3. Refer to the parameters of similar equipment, and do the same project test at the same time, the results are compared, and the exact test report is given.

(III) ability to analyze insulation accidents

Through the analysis of the equipment test results, the causes of insulation accidents are obtained. Propose solutions to prevent the recurrence of insulation accidents.

At present, there are many electrical high voltage test equipment installed outdoors, which is greatly affected by the environment. Therefore, the insulation of electrical equipment is easily damaged, and most of the accidents in the power system are caused by the damage of equipment insulation. There are many reasons for insulation deterioration or damage. But summed up mainly chemical, temperature, mechanical and electrical four:

1) Chemical reasons:

The insulation of electrical high-voltage test equipment is composed of organic insulating materials (such as rubber, plastic, fiber, asphalt, paint, wax, etc.) and inorganic insulating materials (such as mica, asbestos, quartz, ceramics, glass, etc.). These materials work outdoors for a long time to withstand the erosion of natural factors such as sunshine, wind and sand, rain and fog, ice and snow. Electrical equipment working at high voltage is also often affected by changes in temperature, air pressure, and air temperature. Although electrical equipment working in an environment containing chemically corrosive gases has certain resistance, insulating materials will cause a series of chemical reactions in these factors for a long time. Changes in the performance and structure of the insulating material, reducing the electrical and mechanical properties of the insulation.

2) Temperature reasons:

Temperature rise is an important factor causing insulation aging, electrical equipment overload, short circuit or local media loss caused by excessive overheating will make the insulation material temperature greatly increased, resulting in thermal stability damage caused by thermal breakdown.

During the operation of the electrical high voltage test equipment, the temperature of the insulation changes very harmful due to the change of the load and the pulsation of the temperature of the cooling medium. Organic insulating materials, which are widely used in electrical equipment, can cause elastic fatigue and fiber breakage of the insulating medium under the action of long-term temperature pulsation. And the insulation material aging.

When the temperature changes dramatically, it will crack the insulation or seal the poor. Insulating materials are often closely combined with metal materials. Due to the large difference in thermal expansion coefficient between the two, when the temperature changes, great stress will be generated in the interior of the insulating material or at the junction of the two, causing insulation damage.

3) Mechanical reasons:

In addition to the electric field, the insulation of electrical high voltage test equipment is also subject to external mechanical load, electric force and mechanical vibration. The insulator of the transmission line serves as insulation. Also long-term bear the role of wire tension. The isolating switch post insulator shall bear the action of twisting moment during the opening and closing operation. Under the action of external mechanical force and electric force, the insulation material will be cracked, which will greatly reduce the electrical performance of the insulation and even cause major accidents.

4) Electrical reasons:

The function of insulation is to separate conductors of unequal potential. The quality of insulation is the strength of the withstand voltage of electrical high-voltage test equipment. Electrical high-voltage test equipment of various voltage levels need to have corresponding voltage resistance. The insulation strength of electrical high-voltage test equipment should ensure that the insulation can operate safely under the continuous action of the working voltage and the short-term overvoltage exceeding a certain value of the working voltage.

The scope of application of the HDZJ-10kV: to meet the rated working voltage 380V-6600V various types of micro motors and other small and medium-sized motors, high-voltage motors. Also meet the motorcycle, automobile industry and other low-voltage DC motor, starter motor, vacuum cleaner motor and Y80-Y355 motor all applicable.

HDZJ-10kV inter-turn voltage tester can check the following faults:

turn-to-turn insulation breakdown

corona discharge

Wrong connection of winding and wrong wire embedding

Winding disconnection

difference in number of turns

Local short circuit between phases to ground, between winding phases or between winding and core.

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