“PASL-3000” – Online Oil-gas Monitoring System with the laser photo-acoustic spectra transformer

  • peculiarity/
  • function/
  • parameter
  • system advantages

    Comparing with the traditional online oil-gas monitoring equipment of oil chromatographic and oil-gas monitoring system of wide light source & photo-acoustic spectra, the online oil-gas monitoring system with the laser photo-acoustic spectra transformer developed and produced by our company has many advantages, as the following table:

    Table2. The online oil-gas monitoring system comparison of multiple transformers


    Online chromatography

    Traditional photo-acoustic spectroscopy

    online oil-gas monitoring system of optical fiber sensing transformer

    System structure

    More complicated structure, the gas composition separating degree and sample quantity are all depending on the system structure.

    Less complicated structure, though it doesnt need the gas composition separating degree, the optical filter and chopper are all belonging to mechanical rotating control, it has a high fault rate for long-time work.

    Easy structure, no need for gas composition separating degree and fibre-optic link, no mechanical vibration, with high reliability.

    Detecting ways

    FID, TCD, gas sensor, with poor ability to detect repeatability and resist cross interference.

    Photo-acoustic spectroscopy, wide spectrum light source matches with narrowband filter. Tough it has been through the narrowband filter, it will still cause the gas besides the characteristic ones involving the laser production process due to not small enough optical signal bandwidth, and finally eliminate cross interference by data fitting, but its reliability is low. The optical signal will provide pulse light source through chopper to increase mechanical vibrating interference.

    Photo-acoustic spectroscopy, DFB butterfly-shaped laser light source with super narrowband, current modulation, to decrease  mechanical vibration, the super narrowband optical signal can inspire the single characteristic gas to avoid cross interference.

    Testing time

    Minimum detecting time  >2 hour

    Minimum detecting time  1 hour

    Minimum detecting time  1 hour


    Need chromatographic column, heater, need gas and carrier gas with high purity.

    No need for consumable

    No need for consumable


    It needs to calibrate with the gas at regular time.

    A one-time calibration

    A one-time calibration

    Daily maintenance

    Changing the chromatographic column and carrier gas at regular time, the system needs to calibrate. High maintaining cost and workload.

    No need for daily maintanance. Low maintaining cost and small workload.

    No need for daily maintanance. Low maintaining cost and small workload.

    Working life

    The life of chromatographic column and sensor are 2-4 years, while the life of gas and carrier gas are 2 years.

    Mechanical photo-acoustic spectra module, its life is beyond 5 years.

    Optical sensing photo-acoustic spectra module, its life is beyond 10 years.

    Testing precision

    Normal precision, poor repeatability, and the C2H2 minimum measuring botoom limit is hard to get the national standard 1ppm.

    Less high precison, great repeatability and well ability to resist cross interference.

    High precison, great repeatability, well ability to resist cross interference depending on narrowband light source. The C2H2 minimum measuring botoom limit is getting 0.5ppm.


    The primary investment is not much while the secondary maintaining investment is much. The overall investment increased.

    The primary investment is much while the secondary maintaining investment is less.The overall investment is ecnomic.

    Longer working life. Coparing with the traditional photo-acoustic spectroscopy, the primary and secondary investment is both less.The overall investment is more ecnomic.





       The online oil-gas monitoring system with the laser photo-acoustic spectra transformer developed by Wuhan HAOMAI Optoelectronics Technology CO., LTD, we creatively combined semiconductor laser technology with gas photo-acoustic spectra detecting technology and applied them to the transformer online oil-gas monitoring of power system. It can online monitor the transformer insulating oil H2, CH4, C2H6, C2H4, C2H2, CO, CO2 and H2O thest eight error gas capacity, and provide alarm. This online monitoring system is easy to operate and maintain, and has accurate measurement, it’s well appreciated by the customers.
        If the online oil-gas monitoring system with the laser photo-acoustic spectra transformer applys the light sound effect to realistic detection, then the first step is to make sure the special molecular absorption spectrum of every gas. Coparing with the traditional light source structure which is combined wide spectrum light source with multiple filtering slices, our oil-gas monitoring system adopts several laser light source and laser driver module to produce the stable impulse optical signal with super narrowband. Its advantages are accurate measurement and ignoringcross interference. The oil pump will control the transformer oil circulation to get through membrane tube without gas, and the error gas waiting for detection will be sent into photoacoustic pool. The optical signal shoot into photoacoustic pool to stimulate gas molecules, and the stimulated molecules will back to groud state after losing inspection through radiating or nonradiating ways. The gas absorption sealed in photoacoustic pool will finally convert to molecules kinetic energy and cuase the local variation of gas pressure, so as to produce cycling mechanical pressure volatility, that is light sound signal. This light sound signal is pretty weak and easily gets the interference by surrouding environment. Setting a micro sound device in photoacoustic pool can convert light sound signal into electrical signal. And the relative value through series of weak signal process, such as amplification and filter etc, and DSP digital phase locking technology is the concentration of corresponding samples’ containing gas. Meantime, we have prepared teledata communication and LCD data display to satisfy customers’ various detecting needs.

    Picture1. Module sketch of online monitoring system

    The construction of complete intelligent grid may increase the requirments about transformer online monitoring device. This needs us to get overall technical comparison and analysis when choosing the products lectotype to decrease daily maintaining work and increase the stability of electrical equipment. The online monitoring device detecting by photo-acoustic spectroscopy with more advanced detecting choice mode, more convenient daily maintainance and lower comprehensive costs will become the main trend for this industry.
    The online oil-gas monitoring system with the laser photo-acoustic spectra transformer developed by our company can find the early errors may existed in the device, to provide judgement for power operation and device maintainance, so as to increase the power supply possibility and economy to futher bring convenience for users.


  • 1 operating indicators

    power supply: 220V, 1kW

    weight: <100kg

    Boundary size: 690(W) x 580(D) x 120(H)cm


    Temperature:  environment temperature: -40℃ ~ +55℃ (-10℃ ~ +55℃ when starting)

    Device oil tube temperature: -10℃ ~ +110℃

    Humidity: 10 ~ 100%RH

    protection grade: IP56

    Oil pressure: on operation   0~3bar0~45psi)  

     Off operation  -1~6bar-15~87psi

    2、  detecting indicators

    Table1.  Detecting index of online oil-gas monitoring system with the laser photo-acoustic spectra transformer

    Failure gas species

    The lowest detection limit uL/L

    The highest detection limit uL/L

    Measuring errors




    The lowest detection limit ±30%the larger one is the final measuring error






















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