Dear Gentleman, It is very nice for us to introduce our updated protector for Oil-immersed transformer,this equipment can completely prevent explosions and fires for big oil-immersed transformers ranging from 5MVA-1000MVA to avoid potential and existing risks of transformers happening, it is the unigue safety equipment we are making in the world. As you might know that each year there are so many explosion and fire of oil-immersed transformer worldwide caused: over-use,over-temperature,ageing of insulation and so on,Unfortunately，the existing Self protection device cannot prevent transformers from explosion and fire and our safety equipment can completely prevent transformers from explosion or fire within 10 ms (10 millisecond), it is unique and most effective device worldwide. So, what we can ensure you is that: No explosion and fire for oil immersed transformer within 30 years. Thank you once again for your kind understanding. Truly yours Mr.Dneg Qing, G/M Beijing Zhongruihe Electrical Co.,Ltd Website: www.bj-zrh.com Email: dengq@bj-zrh.com M/P and WhatApp: +86 13011214100