The first thing to know is what y and h mean. Y stands for "metal oxide", which is what we usually call zinc oxide arrester; H stands for "composite jacket", which is what we usually call silicone rubber arrester. Connection mode: silicon rubber zinc oxide arrester.

So YH and HY are the same. So why are there two different ways to write it? This is because the expression order of previous national standards is different, which leads to the inconsistent alphabetical order of previous national standard products.

After 2000, the industry gradually unified the model expression to YH. HY products still exist in the market, mainly the upgrading of old projects and products, and some design units and production enterprises are blocked from information, which can't keep up with the development of the industry.