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The Common Faults Of Current Transformers Are Often Related To Manufacturing Defects, As Follows:
Aug 19, 2017

The common faults of current transformers are often related to manufacturing defects, as follows:

1) insulated current transformer is very thick, some wrapping insulation loose, insulating layer between the fold, and the vacuum impregnation is not completely bad, caused by the gas cavity, thereby causing partial discharge fault.

2) the size and arrangement of the capacitor screen do not meet the design requirements,

Fault cause statistics of current transformer

Fault cause statistics of current transformer

Even less capacitive screen, capacitor plate is not smooth, even dislocation or fracture, so that the pressure characteristics of destruction. Therefore, when the local solid insulation along the surface of the field intensity reaches a certain value, it will cause partial discharge.

The direct consequence of the partial discharge is that the insulating oil is cracked and a large amount of X wax is generated between the insulating layers, and the dielectric loss is increased. This discharge has a cumulative effect, allowing it to develop, and gas analysis in oil will probably present characteristics of arc discharge.

3) a surface discharge may occur on the surface of the material due to its poor cleanliness or moisture content. This situation is often seen in a terminal lead, along the block surface discharge.

4) some loose connections or metal potential suspension will cause spark discharge, such as a winding support nut loose, causing a potential suspension winding shielding foil, lead to bad welding end screen contact or even disconnection, can cause such failures.

5) the secondary connection plate, the bolt and the nut are loose, the end plate grounding nut is loose, the tap fastening nut is loose, etc., all may cause the contact resistance to increase, thus causes the local overheating fault. In addition, attention should be paid to on-site maintenance and mismanagement. For example, the transformer inlet water is affected, although it may be related to the sealing structure of the manufacturer and sealing materials, but there are also maintenance and management issues. Generally speaking, the vacuum degassing in the field is not enough or vacuum drying is not performed during the overhaul, which makes the dissolved gas in the oil easy to saturate or the residual bubbles and humidity in the oil paper insulation are higher. All of this will leave the device with a security risk.


Add: No.38 South Taoyuan Road, Yaozhuang Town,Jiashan County, Jiaxing City, Zhejiang Province, China
Contact person: Elva Zhuang&Sunny Ni
Tel:+86-573-84775555
Fax:+86-573-84776699
Phone:+86-13732570078
E-mail:sales9@great-relay.com
sunny.ni@great-relay.com