Ground lead current signal monitoring sensor for end screen of transformer bushing

Abstract

The invention provides a ground lead current signal monitoring sensor for an end screen of transformer bushing. The ground lead current signal monitoring sensor comprises a conducting rod 1, a pedestal 2, a bottom waterproof sealing ring 3, a coil 4, a coil 5, a coil 6, a housing 7, a waterproof cap 8, a conductive disk 9, a top waterproof sealing ring 10, a BNC contact 11, a BNC contact 12, and a BNC contact 13, wherein the coil 4, the coil 5 and the coil 6 sleeve the conducting rod 1 side by side, and shares the housing 7; the conducting rod 1 is cylindrical; the housing 7 is cylinder-shaped; the conducting rod 1 and the housing 7 form a coaxial cylinder structure; and the pedestal 2 is a cylinder, and the pedestal 2 and the conducting rod 1 forms a coaxial cylinder structure. The ground lead current signal monitoring sensor for an end screen of transformer bushing can transmit high frequency signals in the 1MHz-40MHz scope without distortion, and is small in volume and high in adaptability.

Description

technical field [0001] The invention belongs to the field of on-line monitoring of transformer bushings in power systems, and relates to a current signal monitoring sensor for the grounding wire at the end screen of the transformer bushing. Background technique [0002] The failure rate of transformer bushings is high, so online monitoring of transformer bushings is very important. Usually, transformer bushing monitoring includes dielectric loss tangent tgδ and bushing partial discharge. When monitoring the above parameters, it is necessary to obtain the current signal from the lead-out line at the end screen of the transformer bushing. [0003] 1) Monitoring of transformer bushing dielectric loss tangent tgδ [0004] The dielectric loss tangent tgδ value of the bushing reflects the damp condition of the bushing insulation, and the δ angle is the angle between the power frequency leakage current on the outlet line of the end screen of the bushing and the power frequency vo...

AI Technical Summary

Problems solved by technology

After the monitoring is completed, remove the sensor and restore the rainproof cap; or use a complex external sealing device to ensure that the grounding wire connector does not rust and has a complex structure

[0011] Since this additional grounding wire is placed randomly and has different lengths, the inductance of the grounding wire itself changes accordingly, which in turn causes the measurement error of the current sensor on the current signal on the lead-out wire of the last screen.

For the power frequency leakage current signal, since the ground wire cannot always be in the center of the current sensor and is bent at will, the resulting phase error cannot meet the accuracy requirements of tgδ measurement

For the partial discharge pulse current signal, due to the non-coaxial cylindrical structure between the ground wire and the transformer shell, the frequency band of the ground wire is not wide enough, and the high frequency (above 1MHz) signal is distorted

[0012] At the same time, the existing current sensor has a large volume, which increases the overall volume of the current monitoring device

For transformers with a voltage level of 110kV and above, considering the impact on the flashover voltage of the transformer bushing, the large-sized current sensor needs to be installed far away from the bushing for monitoring, and it cannot even be accepted by field personnel, so it is not practical

In addition, there are two parts that need to be sealed in the method of adding a ground wire to the lead-out wire of the last screen, that is, the two ends of the ground wire, so the requirements for the sealing structure are relatively high

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