Analysis of Common Faults of Miniature Current Transformer

Usually, the common failure of Miniature Current Transformer is often related to its own manufacturing defects. For example, if the insulation of the current transformer is very thick, some of the insulation is loosely wrapped, and there are wrinkles between the insulation layers, coupled with poor vacuum treatment and incomplete impregnation, resulting in an air-containing cavity, which is more likely to cause partial discharge. Fault.

When designing, the size and arrangement of the capacitive screen of the Miniature Current Transformer do not meet the design requirements, or even less capacitive screen is placed, and the capacitive plates are not smooth and flat, or even dislocated or broken, which will cause damage to the voltage equalization characteristics. Therefore, when the electric field strength along the surface of the local solid insulation reaches a certain value, partial discharge will be caused. In view of such a situation, it is necessary to deal with it in time to avoid the characteristics of arc discharge.

In the process of manufacturing the Miniature Current Transformer, if the insulating material used is contaminated or has high moisture content, creeping discharges may occur on its surface. This situation is more common when the terminal lead discharges along the surface of the pad. Similarly, if some connections are loose or the potential of metal parts is suspended, it will lead to spark discharge. For example, the primary winding support nut is loose, causing the potential suspension of the primary winding shielding aluminum foil, and the final screen lead contact or poor welding or even disconnection will cause such faults.

During the combined connection, if the connecting splint, bolts and nuts of the Miniature Current Transformer are loose, the grounding nut of the last screen is loose, and the tap fastening nut is loose, etc., the contact resistance may increase, resulting in local overheating failure. In addition, improper on-site maintenance management should also be paid attention to.

This is because if the Miniature Current Transformer gets wet, on the one hand, it may be related to the sealing structure and sealing material used in the manufacturing process, and at the same time, there are maintenance management issues. Generally speaking, the on-site vacuum degassing is not sufficient or the vacuum drying is not carried out during maintenance, resulting in easy saturation of the dissolved gas in the oil or high residual air bubbles and moisture content in the oil-paper insulation. All of these will leave a security risk to the Miniature Current Transformer.