Measures to reduce partial discharge of transformers

1. Dust control

Among the factors that cause partial discharge, foreign matter and dust are very important factors. The test results show that the metal particle with the diameter of Phi 1.5μm can generate much more than 500pC discharge under the action of electric field. Whether it is metal or non-metal powder, a concentrated electric field will be generated, so that the initial discharge voltage of the insulator is reduced, and the breakdown voltage is reduced. To this end, it is very important to keep the environment and the body clean during the transformer manufacturing process, and dust must be strictly controlled. Strictly control the extent to which the product is affected by dust in the production process, and establish a sealed dust-proof workshop.

GDPD-414 portable partial discharge live inspection instrument

2. Centralized processing of insulation parts

It is very important that it contains metal dust, because once the insulation sheet is attached to the metal dust, it is difficult to remove it completely. Therefore, the treatment must be centralized in the isolation workshop and set up an area that must be isolated from other dust-producing areas.

3, strictly control the processing of silicon steel plate burr!

Transformer core parts are formed by longitudinal and transverse cutting. These cuts have varying degrees of burr. Burrs not only cause short circuits between chips, but also increase losses and increase the thickness of the core. What’s more: When the core is inserted into the yoke or subjected to vibration during operation, burrs may fall on the fuselage and a discharge may occur. Even if the burr falls to the bottom of the box, it can be arranged in order under the influence of the electric field, causing the ground potential discharge. Therefore, core burrs should be as small as possible. The core burrs of 110KV products should not be greater than 0.03mm.

4, lead, cord end terminal

The use of lead cord end terminals is an effective measure to reduce local discharge. When using phosphorus copper welding, a large number of splash welding slag will be formed, which is easy to spread to the body and insulator parts. In addition, the source boundary area must be separated with submerged asbestos wire so that water can enter the insulation. If the water is not completely removed after the insulation winding, it will increase the partial discharge of the transformer.

5, rounded edge components

The purpose of rounding the edges of parts:

Improve the field power distribution and increase the initial discharge voltage. Therefore, the metal structural parts such as clamps, pull plates, pads and support edges in the iron core, pressure plates and outlet edges, the wall of the box riser and the magnetic shield on the inside of the box wall must be rounded. .

Prevent iron filings from friction. For example, the contact part of the hanger hole of the clip with the lanyard or hook should be circular.

6. Product environment and body coating during final assembly

After vacuum drying of the hull, the hull should be sorted before packaging. The larger the product, the more complex the structure and the longer the completion time. When the valve stem is compressed and the fastener is tightened, the valve stem is exposed to air, during which moisture absorption and dust dispersion occur. Therefore, the body should be cleaned in dust-proof areas such as when finished (or exposed to air). Time) more than 8 hours, must be dried again. After the hull is completed, the vacuuming and tank filling phase begins. Since stem insulation absorbs water during the stem dressing stage, it is necessary to dehumidify the stems. This is an important measure to ensure the insulation strength of high-voltage products. The method used is to vacuum the product. Determine the vacuuming time according to the body,

7. Vacuum lubrication

The purpose of vacuum oil injection is to inject transformer oil in the vacuum, eliminate the dead Angle in the product insulation structure by vacuuming the transformer, completely evacuate the air, and then completely absorb the transformer body. After oil injection, wait at least 72 hours before testing the transformer, because the degree of penetration of the insulation material is related to the thickness of the insulation material, the temperature of the insulation oil, and the time of immersion. The higher the degree of penetration, the less likely it is to ejaculate, so make sure enough absorption time has passed.

8. Sealing of fuel tank and parts

The sealing structure is directly related to the leakage of the transformer. If there is a leakage point, water will inevitably enter the transformer, causing transformer oil and other insulating parts to absorb moisture, which is one of the factors for partial discharge. Therefore, it must meet a reasonable sealing value