Currently there are two types of minerals in China: wolframite and scheelite. Tungsten is a kind of rare metal and significant strategic material. It is called "heavy stone" from ancient China. In 1783 tungsten was named by the Spaniard DE Puria. The tungsten content in the crust is 0.001%. Generally the tungsten ores are formed for the activity of granitic magma. Tungsten is a silver-white shiny metal with high melting point and high hardness after smelting. There are more than 20 types of tungsten minerals and minerals containing tungsten which are discovered.

Tungsten contact is widely used in switches as a part to connect or disconnect the electricity. The so-called tungsten switch contact can be simply understood as the switch's contact point is made of metal tungsten, which has good heat resistance, lower resistance, good chemical stability and other advantages, and can be very good circuit connection or break, thereby reducing the probability of electrical equipment failure.

China has the largest tungsten reserve and tungsten output whose reserve are four times of  other countries in the world, tungsten ore was found early 10th century and was called "heavy stones" at that time. Tungsten ore in China is mainly located in the Sanjiang tungsten tin metallogenic belt,West Qinling-Qilianshan metallogenic belt, Tianshan-Beishan metallogenic belt, south China metallogenic belt and north China metallogenic belt. Nanling metallogenic belt is the most richiest in south China metallogenic belt, and numerous large and super large tungsten ores are distributed in this metallogenic belt with more than 70% reserve of China. The tungsten ore in China was mainly formed in Yanshanian era accounting for 83%, Hercynian era 9%, Caledonian era 4%, Precambrian era 2% and Indosinian era 2%.

AC contactor is applied tungsten copper or tungsten iron contact as main connecting parts. AC refers to alternative current. Why tungsten contacts are selected for the contacts of AC contactors? Tungsten as raw material made contacts are with superior properties.