My basic knowledge on the quality and competitiveness of Vaisala transformer products and information is very positive. One recommendation I would volunteer is as follows; " Critical fault gases and why they form" often cause many transformers users great expense when trying to comply with gas-in-oil guidelines from IEEE, IEC or independent companies. It should be noted that all power transformers generate gases (including fault gases) during normal and abnormal operation based on loading, transformer age and ancillary items on the transformer.