K type thermocouple is nickel chrome - nickel silicon thermocouple. The principle of thermocouple type K thermocouple it is a cheap thermocouple to measure high temperature. Because of this alloy has good high temperature oxidation resistance, can be applied to oxidizing or neutral medium. It can measure the high temperature of 1000 degrees for a long time, short-term measurable to 1200 degrees. It cannot be used for reducing medium, otherwise, the corrosion soon, in this case can only be used under 500 degree measurement. K type thermocouple is much cheaper than the S type thermocouple, the repeatability is very good, the thermoelectric potential big, about 0. Mv / 041 degrees, thus high sensitivity, and it has a good linear. Although the measuring accuracy is slightly low, but can satisfy completely the requirements of industrial temperature measurement, the K type thermocouple is very frequently used in industrial thermocouple. It is two different materials of metal conductors closed loop, one end on the measured medium feel the temperature change, known as hot side, the other end to the cold end. When the cold end and the hot end temperature at the same time, not in the loop will produce certain direction and the size of potential, so that the cold end temperature is constant, the thermoelectric potential associated with the other end temperature, only in this way, as long as the measured the size of thermoelectric potential can know the size of the temperature. So the thermocouple can not consider current, measuring its millivolt voltage line.