Will you lose money if you fail the winding withstand voltage test of the transformer factory?

In this case, there is generally no problem at all, you can lose money, and relatively speaking, there are strict regulations in this regard.

If the transformer factory has not passed the withstand voltage test, this is not passable, this does not need to lose money, they just did an experiment in their own factory, and did not say, uh, there are some accidents after buying before they need to lose.

If the test has not passed, it means that there is a quality problem, and the manufacturer should be responsible!

This kind of money needs to be lost, and if the damage is caused by personal reasons, it is necessary to lose money.

In this case, there is no problem at all, yes, and relatively speaking, he can lose money to you, and there are strict rules in this regard.

I feel that in this case, of course, the business can lose money, so as long as there is no danger occurring, it can be used normally.

Transformer factory winding withstand voltage test, of course, can not say whether to lose money or not? Because these trials are necessary, the cost of this aspect must be incurred.

I'm glad you need to lose money on this experiment, but be sure to pay attention to your time and speed of speech.

The electrical loss of the transformer and transformer is a fixed value, why does the cable heat up, is the cross-sectional area small? Or is it too much of a load? You can calculate the total power of the load plus the electrical loss of the transformer compared to the actual electricity consumption now.

The safety of the skeleton does not match the thickness of the flesh. For example, if the thinnest flesh thickness of PM-9630 is tested by UL, if your wall thickness is lower than this thickness, it is reasonable to have poor pressure resistance.

If the mold is ok during mass production, but NG in the process, it may be caused by uneven meat thickness caused by mold eccentricity or misalignment 2Yes.

If the toilet manufacturer has not been inspected, or if it does not meet national standards, it may be repatriated.

That aura wants that test has not lost money.

Will the transformer factory lose money if the line withstand voltage test is not passed? It depends on how you negotiate.

The transformer factory winding withstand voltage test has not passed, in fact, it should lose money.

The winding withstand voltage test of the transformer factory has not been lost by taking medicine.

I think in this case, if there is a quality problem, a claim must be saved.

Do you have to lose money if you don't pass the withstand voltage test? Not necessarily.

The transformer factory has not been wound to ATV, do you want to lose money? The transformer factory winding withstand voltage test has not passed, and it will lose money.

The transformer factory has not passed the winding withstand voltage test, of course, it will lose money.

Inspect the insulation level to see if the insulation is good and whether it can maintain the insulation performance at the rated voltage or a voltage higher than the rated voltage.

If you don't, you don't know if there's a dead pixel or a local short circuit. In case there is, isn't it a hassle that you can't use it when you send it to the customer and have to ship it back?

The transformer withstand voltage test (external high voltage test) is mainly to check whether the main insulation of the transformer is qualified, that is, the insulation between the primary coil and the secondary coil, between them and the core and shell. If it is not qualified, it will not only endanger the damage of the transformer itself and other connected electrical installations, but also cause danger to the equipment and personnel who use electricity.

The withstand voltage test is to use the frequency test transformer to add a certain AC high voltage, which lasts for one minute, if the insulation does not break down or the leakage current does not exceed a certain value, it is qualified. For example, oil-immersed power transformer, 10kV, factory test and handover test are kV respectively.

Transformers occupy a very important position in power operation equipment, and must be tested after new installation and overhaul to ensure their safe and economical operation. According to the actual situation, we need to carry out routine tests, type tests or special tests, and here we mainly introduce the commonly used insulation tests and characteristic test items.

1) The withstand voltage test is a destructive test, and the insulation resistance test should be carried out before and after the test, and the difference between the insulation resistance before and after the withstand voltage should not exceed 30%;

2) Before pressurization, carefully check whether the wiring is correct and keep a sufficient safety distance;

3) The boost must start from zero, and the boost speed can be quickly increased before the 40% test voltage, and then the voltage should be evenly boosted at the speed of 3% of the test voltage per second.

Because the applied voltage is higher, the withstand voltage test has an impact on the insulation life of the transformer, and if the low-voltage transformer has no abnormal condition during operation, it is best to do the withstand voltage test as little as possible, and the actual maximum is 8 years.

Handover tests are slightly more expensive, and preventive tests are cheaper. The specific cost should be determined according to the test project, voltage level and difficulty (mainly the size of the equipment). There are several non-standard items in the transformer test, whether they are all done and so on.

You can contact Shanghai Dafan Electrical Equipment****, cables, transformers, generators, motors, GIS and other AC withstand voltage tests are available.

It is recommended not to look for a power company, but to find a private installation company with relevant power qualifications, the cost will be much cheaper.

The power bureau has a special one for this, so you can ask them.

Safety comes first, because it's high-voltage. The voltage level of the sample is tested by applying the corresponding voltage.

In the transformer withstand voltage test process, of course, the transformer power supply needs to be powered off, because it is to test the transformer withstand voltage, the transformer needs to be high-voltage, and the original power supply line is not opened, so the high voltage is not very dangerous to send to the user line.

The power must be cut off! The withstand voltage test should never be carried out with electricity.

Withstand voltage test process: 1. Power off; 2. Discharge static electricity; 3. Detect the insulation point resistance and make a record; 4. In addition to the pressurized phase, other windings, terminals, and shells need to be grounded; 5. Pressurize, keep time, and make records; 6. Stop pressurization, discharge static electricity, detect and detect insulation point resistance and make a record.

A preventive test is mandatory every two years, and the test report is provided to the local power supply authority. Preventive tests include withstand voltage, insulation, and other tests, less than two years from the last test, generally small problems do not test, waste money.

1. External pressure test.

Test: The external withstand voltage test is a test of the power frequency high voltage of the tested transformer plus one minute, which is also known as the power frequency withstand voltage test. It is to assess the insulation performance between different side windings and between windings to ground, that is, to assess the level of main insulation of transformers, so it is only suitable for fully insulated transformers.

Therefore, the windings on the different sides of the transformer under test are connected together, with voltage applied to one winding and grounding on the other. When the external withstand voltage test is applied, it is closed when the power supply voltage is low; When the test power supply voltage reaches less than 40% of the test voltage, the boost speed is arbitrary; At 40% or more, it should be at 3% per second

The speed rises evenly; After reaching the specified voltage and duration, the voltage should be quickly and evenly reduced to the test voltage within 5s.

25% or less to cut off the power supply.

2. Induction withstand voltage test: The induction withstand voltage test of fully insulated transformer is the open circuit of the high-voltage winding, and 100 250Hz is applied to the low voltage

Withstand voltage test of twice the rated voltage. Due to the increase in frequency, the core can ensure twice the induced voltage when it is not saturated, so that the insulation performance between turns, layers and phases of the winding is tested, that is, the longitudinal insulation level of the transformer is assessed. For the transformer with graded insulation, the neutral point voltage is raised (supported) to assess the level of the main insulation. In this way, the induction withstand voltage test not only carries out the test of longitudinal insulation, but also remedies the deficiency that this kind of transformer can not do the external withstand voltage test, and also does the external withstand voltage test equivalently at the same time.

The sensory transformer of graded insulation is often tested by split-phase induction test.

Test method. The non-test two-phase line end is connected to the ground in parallel, and the neutral point is raised to about 1 3 of the voltage, so that the test phase line end meets the requirements of the external withstand voltage test, and the induced voltage of the phase winding meets the requirements of the induction test.

If this does not meet the test requirements, the position can be adjusted, and even another transformer can be used as a support transformer to support the neutral point. The new standard requires that the partial discharge amount, starting and extinguishing partial discharge voltage should be measured during the induction test.

3. Impulse voltage test: impulse voltage test is divided into lightning impulse test (including full wave impulse test and interception wave impulse test) and operating wave impulse test. In the newly compiled IEC76-3 standard, for transformers smaller than UM, the full-wave impulse test and the interception and operating wave impulse tests are routine tests.

For UM transformers, the full-wave impulse test is a routine test, the interception impulse test is a type test, and for the U-252kV transformer, the full-wave, interception and operating wave impulse tests are routine tests. The full-wave and interception wave impact tests are carried out alternately, generally with negative polarity, and one full-wave impact is done first, two interception shocks, and then two full-wave shocks. Therefore, a cut-off device is required.

When the transformer capacity is large, when the waveform cannot be satisfied due to the large capacitance, the impulse voltage generator should be operated in parallel in several stages. When the impulse test is carried out on the midpoint of the transformer, because it is a three-phase incoming wave, the capacitance is large, but the test voltage is generally not high, and the impulse voltage generator should be pressurized after several stages in parallel.

The low-voltage side of the transformer withstand voltage test is to short-circuit all the low-voltage windings of the transformer together as one pole, and after all the high-voltage windings of the transformer are short-circuited, they are connected with the shell and ground as another pole, and 4kV power frequency voltage is applied between these poles; When the insulation of the transformer is relatively good, it is possible for the micro-ampere meter to read 0ua;

The cable does not do power frequency AC withstand voltage test, for power frequency, the cable is like a capacitor, there is no meaning;

If you add DC withstand voltage, "three-phase pressure together" is not of much significance, because each single-phase test can already include three-phase insulation inspection; For 10kV cables, when the cable is not long, the cable head is made well, and the cable insulation is good, it is very normal for the microampere meter to read 0-5ua.

The transformer handover test is made according to 80% of the factory test value, the power cable generally does not use AC withstand voltage, using DC, and the transformer generally uses AC withstand voltage, without DC this practice.

Method 1: Power frequency AC withstand voltage test.

The power frequency AC withstand voltage test plays a decisive role in assessing the main insulation strength of the transformer and checking the local defects. This test can effectively find that the main insulation of the winding is damp and cracked, or in the process of transportation, the winding is loose and displaced due to vibration, resulting in insufficient lead distance and dirt attached to the winding insulation.

Method 2: Induction withstand voltage test.

The purpose of the induction withstand voltage test is to:

1. Check the longitudinal insulation of the fully insulated transformer (between coil layers, turns and sections).

2. Check the main insulation and longitudinal insulation of graded insulation transformers (the main insulation refers to the insulation between the windings to the ground, between phases and between windings of different voltage levels. Because when doing the AC withstand voltage test of the fully insulated transformer, only the electrical strength of the main insulation of the transformer is tested, and the longitudinal insulation does not withstand the voltage, so the induction withstand voltage test is done.

Method 3: Transformer partial discharge test.

Due to the complex insulation structure of the transformer, the use of many materials, resulting in the whole insulation system is very uneven, if the structural design is not reasonable, the local electric field strength will be too high, the manufacturing process is poor, such as vacuum drying, vacuum immersion is not thorough, the insulation system contains air gaps, residual bubbles, these are the causes of partial discharge. This partial discharge can cause damage to the oil-paper insulation in a relatively short period of time. If it continues, it will cause insulation breakdown.

The traditional transformer insulation test is difficult to find the above problems, because the partial discharge generally only affects the long-term operating life of the transformer insulation, and will not reduce its short-term electrical strength, so the transformer may successfully pass the 1min withstand voltage test, but can not guarantee the reliability of operation, that is, the conventional test method can not detect the partial discharge in the insulation. The partial discharge test of transformer is an important measure to ensure its reliable operation.

Method 4: Measure the insulation resistance and absorption ratio.

Measuring insulation resistance and absorption ratio is a simple and versatile way to check the insulation status of a transformer. Generally, the insulation moisture and local defects, such as porcelain cracking, lead wire grounding, etc., can be effectively detected. Experience shows that the change factor of insulation resistance of transformer insulation before and after drying is much greater than the change factor of the dielectric loss angle.

Therefore, in the drying process of the transformer, the megohmmeter is mainly used to measure the insulation resistance and absorption ratio, so as to understand the insulation situation.

Method 5: Leakage current test.

The leakage current test is similar to measuring insulation resistance, but due to the higher applied voltage, some insulation defects that cannot be detected by the insulation resistance test can be found. Such as partial penetration defects of transformer insulation and lead bushing defects.

Method 6: Measure the tangent of the loss angle of the medium.

Measuring the tangent value of dielectric loss of transformer winding insulation is mainly used to check whether the transformer is damp, insulation aging, oil quality deterioration, sludge attached to the insulation and serious local defects. Because the measurement results are often affected by the surface state of the test specimen and external conditions (such as electric field interference, air humidity, etc.), corresponding measures should be taken to make the measurement results accurate and true. Generally, the tangent value of the winding together with the casing is measured, and sometimes in order to check the insulation state of the casing, the tangent of the dielectric loss of the casing can be measured separately.