Reasons and Solutions for the Loud Sound of Dry-Type Transformers

Dry-type transformers refer to transformers in which the core and windings are not immersed in insulating oil and rely on air convection for cooling.

It can be divided into two types in structure:

(1) Solid insulation encapsulated winding: epoxy resin casting type SC series, German technology, current application mainstream

(2) Unencapsulated winding: H-class open type-SG series, American technology

Generally speaking, the sound of dry-type transformers is stable and relatively soothing. For the sound of dry-type transformers, various faults will occur. The more common sound-related faults of dry-type transformers are The sound of the dry-type transformer is too high. What are the reasons for the excessively high sound of dry-type transformers? How to deal with it?

Reasons for loud noise during dry-type transformer operation:

Reason 1: The space of the power distribution room is too small or multiple dry-type transformers are running at the same time, which is caused by the reflection and superposition of the shell and the wall and floor of the power distribution room.

Solution: It is recommended to paste sound-absorbing material on the wall, and the door panel is made of sound-proof material to reduce noise.

Reason 2: The power distribution room is on the first floor or upstairs, and the vibration of the dry-type transformer during operation is easily transmitted to the adjacent room through the floor slab, causing the noise.

Solution: For small-capacity dry-type transformers, you can add rubber pads underneath the dry-type transformers. Large-capacity dry-type transformers need to add a shock absorber. The better the vibration reduction effect, the more noise reduction.

Reason 3: caused by high grid voltage

Determine the voltage overvoltage range by checking the indication of the voltage meter of the high and low voltage cabinet, adjust the connection piece of the tap after power off, and connect it to the corresponding position according to the signs on the nameplate and tap indicator plate.

Reason 4: There are rectifiers, variable frequency speed regulators, electric arc furnaces, capacitors, and other power electronic equipment in the load. This equipment generates a large number of high-order harmonics during operation, which makes the dry-type transformer produce a lot of noise. After stopping, the dry-type transformer sounds normal.

Solution: Use a harmonic analyzer to measure the voltage total harmonic distortion THD (10KV power grid ≤4.0%), and provide the harmonic content to the manufacturer to improve the load quality.

Reason 5: The low-voltage busbar of the dry-type transformer or the low-voltage cabinet bus tie bridge is not firmly fixed, and the operation is vibration and noise.

Solution: Listen to the sound or press with an insulator, the sound will decrease or disappear, and the power will be fixed again. If necessary, add rubber pads to help reduce the shock.

The information is provided by the distribution transformer substation factory.