1. Open the box for inspection before installation

Check whether the packaging is in good condition. After the transformer is unpacked, check whether the data on the nameplate of the transformer meets the design requirements, whether the factory documents are complete, whether the transformer is in good condition, whether there is any sign of external damage, whether the parts are displaced and damaged, whether the electrical support parts or connecting wires are If there is damage, finally check whether there is any damage and shortage of spare parts.

2. Transformer installation

First check the foundation of the transformer to check whether the pre-embedded steel plate is level. There should be no cavitation phenomenon under the steel plate to ensure that the foundation of the transformer has good shock resistance and sound absorption performance, otherwise the noise of the transformer after installation will increase. Then, use the roller to move the transformer to the installation position, remove the roller, and accurately adjust the transformer to the design position, and the installation level error meets the design requirements. Finally, four short channel steels are welded on the four corners close to the transformer base, that is, on the pre-embedded steel plate, so that the position of the transformer does not move during use.

3. Transformer wiring

When wiring, the minimum distance between the electrified body and the electrified body to the ground should be ensured, especially the distance from the cable to the high-voltage coil. The high-current low-voltage busbar should be supported separately, and should not be directly connected to the transformer terminal to cause excessive mechanical tension and torque. When the current is greater than 1000A (such as the 2000A low-voltage busbar used in this project), the busbar and transformer There must be a soft connection between the terminals to compensate for the thermal expansion and contraction of the conductor and to isolate the vibration of the busbar and the transformer. The electrical connection at each wiring must maintain the necessary contact pressure. Elastic elements (such as disc-shaped plastic rings or spring washers) should be used. When tightening the connecting bolts, a torque wrench should be used. The torque reference value provided by the manufacturer is shown in Table 1 shown

4. Transformer grounding

The grounding point of the transformer is on the base of the low-voltage side, and leads out to a special grounding bolt, which is marked with a grounding mark. The grounding of the transformer must be reliably connected to the protective grounding system through this point. When the transformer has a casing, the casing should be reliably connected to the grounding system. When the low-voltage side adopts a three-phase four-wire system, the neutral wire should be reliably connected to the grounding system.

5. Inspection before transformer operation

Check whether all fasteners are loose, whether the electrical connection is correct and reliable, whether the insulation distance between the charged body and the charged body to the ground meets the regulations, there should be no foreign matter near the transformer, and the coil surface should be cleaned.

6. Debugging before transformer operation

(1) Check the transformation ratio and connection group of the transformer, measure the DC resistance of the high and low voltage windings, and compare the results with the factory test data provided by the manufacturer.

(2) Check the insulation resistance between the coils and the coil to the ground. If the insulation resistance is significantly lower than the equipment factory measurement data, it indicates that the transformer is damp. When the insulation resistance is lower than 1000Ω/V (operating voltage), the transformer must be dried.

(3) The test voltage of the withstand voltage test should comply with the regulations. When doing the low voltage withstand voltage test, the temperature sensor TP100 should be taken out, and the sensor should be returned to its place in time after the test is over.

(4) When the transformer is equipped with a fan, the fan should be energized and operated to ensure its normal operation.

7. Trial run

After the transformer has been carefully inspected before being put into operation, it can be energized for trial operation. During the test run, special attention must be paid to check the following points. Check for abnormal sounds, noises and vibrations. Is there any abnormal smell such as burnt smell? Whether there is discoloration caused by local overheating. Whether the ventilation is good. In addition, the following points should be noted.

First, although the dry-type transformer has strong moisture resistance, it is still prone to moisture because it is generally an open structure, especially the dry-type transformer produced in my country has a low insulation level (lower insulation level). Therefore, dry-type transformers can only obtain high reliability when the relative humidity is below 70%. Dry-type transformers should also avoid long-term outages to avoid severe damp. When the insulation resistance value is lower than 1000/V (operating voltage), it means that the transformer is seriously damp, and the test run should be stopped.

Second, the dry-type transformer used for step-up in the power station is different from the oil-immersed transformer. Open-circuit operation on the low-voltage side is prohibited, so as to avoid insulation breakdown of the dry-type transformer due to overvoltage on the grid side or lightning strikes on the line, resulting in overvoltage transmission. In order to prevent the danger of overvoltage transmission, a set of overvoltage protection surge arresters (such as Y5CS zinc oxide arresters) should be installed on the voltage bus side of the dry-type transformer.