Oil-less equipment is very important for the safe operation of power grid. In recent years

power grid accidents caused by transformer bushing faults occur frequently. In order to diagnose the running state of bushing and avoid serious power grid accidents caused by bushing failure

an on-line multi-parameter monitoring device for dissolved hydrogen

oil pressure and oil temperature in bushing oil was developed

including three units: signal acquisition

control cabinet and data analysis. A new hydrogen sensor without oil-gas separation membrane and based on palladiu

m alloy film technology was developed. The structure of the sensor was designed with miniaturization and low power consumption. Si

3

N

4

protective film was deposited on the chip surface

which improved the measurement accuracy and service life of the sensor. A three-in-one sensor for hydrogen

oil temperature and oil pressure has been developed

which has the advantages of miniaturization

lightweight and easy installation. The test results show that the hydrogen measurement range of the sensor is 0～5 000 μL/L

and the measurement accuracy can reach 10% or 15 μL/L（with larger values）;the pressure measurement range is 0～1.0 MPa

the resolution is 0.1 kPa

and the accuracy can reach 0.25 grade;and the temperature measurement range is -40～105 ℃

and the accuracy is ±1 ℃. The measurement performance of the device fully meets the requirement of on-line monitoring of transformer bushing. It has been put into operation in 330 kV substation. It can monitor the bushing status on-line in real time and eliminate the early latent fault of bushing in the weak budding state.