How to use transformer oil chromatography injection aid

0

introduction

Using transformer oil chromatography online monitoring devices to monitor the operating status of transformers is currently the most effective means of online monitoring of latent faults in transformers. With the rapid development of transformer oil chromatography online monitoring devices, their functions are becoming more and more complete [1]. In recent years, the State Grid Corporation of China has vigorously promoted the condition maintenance of power transmission and transformation equipment and the intelligent transformation of power grids within the system. For the condition maintenance of large transformers, it is necessary to rely on the auxiliary technical means of oil chromatography online monitoring devices [2]. As an online monitoring device for substation equipment, the transformer oil chromatography online monitoring device makes up for the deficiency that offline chromatography cannot be monitored at any time [3].

However, in the early stage of use, the oil chromatography online monitoring equipment works normally and its accuracy can meet the requirements. After two or three years or even shorter use, the accuracy of some equipment will seriously decline, the data repeatability will seriously decline, the data will be unstable, and the regular calibration once a year or two will no longer meet the test accuracy requirements. The data drift is serious, resulting in false alarms from time to time, and even no alarm when there is a fault. These have brought many negative impacts on the equipment status assessment of the transformer [4]. Therefore, it is particularly urgent to develop a transformer oil chromatography injection auxiliary device.

1

Overall design selection

According to the principle and characteristics of sample gas injection in transformer oil chromatography analysis test and the goal of developing transformer oil chromatography injection auxiliary device, three basic design schemes are proposed, as shown in Table 1, namely manual injection, electric injection and pneumatic injection.

Table 2 compares the three alternatives in various aspects.

Through comprehensive analysis and comparison, it can be seen that pneumatic filling has great advantages in cost and cycle. This paper decides to adopt the pneumatic filling design solution.

2

Pneumatic filling program implementation

Through the analysis and selection of the above transformer oil chromatography injection auxiliary device schemes, the best scheme is finally determined as shown in Figure 1.

According to the optimal configuration obtained from the above analysis and research, and in accordance with the 5W1H principle, the countermeasures shown in Table 3 are formulated.

3

Prototype production and application

3.1

Processing Japanese-shaped fixings

According to the size of the transformer chromatographic injection syringe, the corresponding Japanese-shaped fixing parts are designed. After the size is determined, a drawing is drawn and the fixing device is manufactured according to the drawing, as shown in Figure 2.

Countermeasure check 1: According to the formula F=mg, m=F/g=45.24/9.8≈4.6 kg, place an object weighing 4.6 kg on the fixture for 24 hours and perform a bending test, as shown in Table 4.

Countermeasure inspection 2: Check the length, width and thickness of the fixings. The inspection targets are length ≥ 100 mm, width ≤ 60 mm, and thickness ≤ 30 mm, as shown in Table 5.

The weight of the fixture was measured and was 250 g.

Assemble the various components according to the assembly drawings, and the actual object after assembly is shown in Figure 3.

The injection auxiliary device can realize the transformation of 6 states, and the action flow is shown in Figure 4.

Installing the sample injection auxiliary device on the upper part of the chromatograph, as shown in FIG5 , can complete the designed action.

3.2

Check target "Pinhole injection deviation <1°"

In order to ensure that the syringe needle is perpendicular to the injection port (maintaining 90°) and the pinhole injection deviation is less than 1° during the transformer oil chromatography test, 50 injection tests were carried out on the device in the laboratory and the needle deviation was measured, as shown in Table 6.

3.3

Check target "sample gas injection time (insertion state + gas injection state + removal state) < 1 s"

In order to achieve a sampling repeatability error within ±1.5%, the sample gas injection time (insertion state + gas injection state + withdrawal state) is less than 1 s. The device was subjected to 50 sampling tests in the laboratory, and the sample gas injection time was statistically analyzed, as shown in Table 7.

4

Conclusion

The use of transformer oil chromatography injection auxiliary device can make the test process simple and orderly, reduce the number of manual operations of test personnel, improve the test accuracy, greatly improve the repeatability and accuracy of chromatographic analysis test injection, save labor and time costs, and reduce the probability of damage to the test syringe and reduce material costs.