Causes and solutions for possible failures of Electrical Current Transformer

1. Reasons for the failure of Electrical Current Transformer

Structure

Generally, when the voltage is higher than 32kV, the material used to manufacture the internal structure of the transformer is usually made of thin paper insulating material. When the voltage reaches 220kV, the internal material of the transformer usually uses capacitive material.

2. The root cause of transformer failure

(1) Failure caused by thermal destruction of insulating materials. Generally speaking, Electrical Current Transformer that can withstand high voltage has better stability, but in a few cases, when large current can pass, but high temperature will cause the temperature of the insulating medium to rise, once it exceeds its temperature, it will rise . At the end of the temperature limit, the insulating material was broken down by high temperature, causing the Electrical Current Transformer to malfunction.

(2) Failure caused by partial discharge. In general, the operation of the main capacitors of 220kV circuit transformers is evenly distributed. However, if the technical process does not meet the standard, the smoothness of the capacitor plate will not meet the process requirements, and if it cannot be grasped, the insulation package will be tight. Then, it will cause the problem of uneven displacement of the capacitive screen. When the card is too tight, the U-shaped clip will cause insulation deformation, and the overall bubble can easily change the voltage distribution, which will make the field strength of a single capacitor screen higher than other capacitors in other cases, resulting in partial discharge. If it cannot be found and handled in time, the capacitor core rod will malfunction.

(3) Humid environment. Due to its poor sealing performance, a strong discharge phenomenon will occur inside the transformer, thereby destroying the insulation of the transformer. The liquid generated in the humid environment is deposited on the bottom of the capacitor core rod, so the bent portion of the capacitor core rod becomes a poor insulation effect, and because it is in a long-term working state, it is easy to form a capacitor core rod breakdown and cause a power failure.

(4) Reasons for insufficient drying and degassing. The Electrical Current Transformer must be vacuum-filled, otherwise the gas cannot be removed and a vacuum cannot be formed. In addition, the degassing time is short and the degassing is not complete. Under the two-way action of voltage and temperature, the current sensor will continue to heat up, causing electrical aging to be interrupted and leading to failure.

(5) Personnel operation error. Common failures of transformers are more likely to cause failures. Most of them are caused by the loosening of the lead connector due to errors in the operation of the personnel. Due to the poor process and secondary windings in the vacuum filling process, open circuits and other conditions can cause failures in these operations to cause overheating or discharge to a part of the power system. These conditions will cause abnormal results in the gas chromatogram of dissolved oil after analysis.