NAJFXD Type Local Discharge Ultrasonic Automatic Positioning Device

The failure testing and positioning of operating the medium and large sized transformers have always been the points that electrical engineers focus for a long time. The NAJFXD system, manufactured in the large-sized transformer local discharge ultrasonic position method and equipment research subject which is one of the national key scientific and technological project has provided an effective solution.

The NAJFXD system has carried the ultrasonic measurement to the local discharge of the hundreds of transformers and reactor in Gezhou Dam 500kV switch station, Wuhan Phoenix Mountain 500kV transformer substation, Shanghai transformer factory, Hefei transformer factory, Hengyang transformer factory, Guangzhou power supply bureau, Hunan electricity generating board, Chongqing transformers factory and Wuhan steel. This system has the advantage of operation reliable and easy to operate. It can meet the needs of measurement. As one of the key items of the of eight-five project, this electrical device has been widely used for the spot test and research in the related unit in the north, east, central and northwest parts of China.

The NAJFXD ultrasonic positioning system which is including the high performance computer, high-sensitivity local discharge sound probe, programmed amplified filter, high-speed A/D transducer, transient waveform recording, signal analysis and fault location software is applied for acquiring, measuring, analyzing, positioning and spot observing the local discharge ultrasonic signal in the large-sized transformer, oil-immersed high voltage electrical apparatus and the GIS electrical operation equipment.

The NAJFXD ultrasonic positioning system can position the fault and the error is less than 250mm. The whole measuring system can find out the local discharge ultrasonic signal which is less than 1000pC.

Functions and characteristics:

(1) Making the detecting operation of local discharge ultrasonic more convenient and the analyzing more simple under the platform of the windows.

(2) Making the signal acquired more reliably for the ultrasonic sensor has the performance of low noise, high-sensitivity and anti-jamming.

(3) Making the spot testing more flexible with the local discharge ultrasonic signal electrical-acoustical position and acoustical-acoustical position functions

(4) Making the result of the position more precisely by choosing freely the spherical position calculation and the hyperboloid position calculation of the ultrasonic signal.

(5) Showing the position coordinates by ultrasonic probe and the locating point by solid geometric drawing.

(6) Convenient for building the measuring and positioning database for further analyzing and managing.

(7) Be the local discharge on-line detecting instrument which is useful for detecting the local generating and developing.

Technical parameter:

The sensitivity of the ultrasonic probe: -150dB

A/D conversion accuracy: 8bit±1/2LSB

Sample length: 32k/channel

Minimum detectable discharge:＜50pC (laboratory)＜300(1000)pC (spot)

Minimum positional error:＜50mm(laboratory)＜ 250mm (spot)