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The problem of the high-voltage fuse of 35kv voltage transformer and its improvement plan

In the normal operation of the voltage transformer, the probability of its internal failure is very small. The high-voltage fuse is often blown because of the resonance of the voltage transformer. When the operation mode of the system changes in some way, the iron core of the voltage transformer is saturated, the inductance and capacitive reactance to the ground are equal or approximately equal, and a relatively large current is generated, causing the fuse to blow. At this time, the voltage transformer must be shut down. Replace the fuse.

 

What we are now using is a quartz sand-filled porcelain tube fuse equipped with a rain cover.

The fuse is installed in the rain cover and fixed with four screws on both sides. When replacing, you must unscrew the screws on both sides, hold the pliers in one hand to fix the nut, and the other hand to tighten the screw. Due to high-altitude operations, there are few places to focus. Such an operation is time-consuming, laborious, and dangerous. The side cover and screws are made of ordinary wrought iron, which is easy to rust and deform due to long-term sun and rain. After the screw is unscrewed, the fixed iron ring is easy to jam due to uneven force, and it is difficult to remove it. Especially in special weather, the replacement has to be postponed, which reduces the reliability of metering and protection.

To overcome the above shortcomings, we can use the rotating shaft type instead of the screw fixed type,

The fixed shaft adopts screws (pins can also be used), the nut and fixed iron ring are eliminated, and the other end of the screw is directly screwed on the side cover. During operation, only unscrew the screw at one end to open the side cover. Even if the fuse cannot be removed due to the obstruction of the connecting wire, another screw can be unscrewed, so that at most two screws can be unscrewed, and it can be done easily with only one hand.

 

To overcome corrosion, the main body of the side cover is made of steel, the outside is plated with anti-rust material (nickel-chromium alloy, etc.), and the screws are made of stainless steel.

The improvement has increased the flexibility and reliability of the high-voltage fuse, reduced the cost, and it easier to operate, creating good conditions for ensuring the safe operation of the system.