How to set up the mosi2 heaters

we learned that the resistivity of molybdenum disilicide electric heating elements increases with the increase of temperature, and the resistivity at high temperatures is about 10 times that at low temperatures.The resistivity of molybdenum disilicide heating elements is much smaller than that of metal heating wires. Its working state is low voltage and large current, so a transformer is generally required. There is a problem with this setting: in the low-temperature section, the resistance of the molybdenum disilicide heating element is about 1/10 of that at high temperatures. If a larger voltage is directly applied, the current will be 10 times that of the element at high temperatures, which will cause a large current impact on the electrical control part and the heating element. This situation generally occurs in the initial stage of power-on and heating of the electric furnace. When the heating rate cannot keep up with the set temperature, the power regulator will output the maximum power, resulting in a large current generated by the low-temperature and low-resistance heating element under a large voltage (the heating element needs a certain time to heat up). Generally, we design that the voltage applied to the element in the low-temperature section should not exceed 1/3 of the working voltage, or if there is a current-limiting function, the current should not exceed the specified working current of the element.Let’s take an example to illustrate how to set the control parameters of the temperature control instrument. For example, there is an electric furnace with 9 φ6/12 heating elements, divided into three groups with three in each group, connected in a star shape. The working parameters of a single element are: 10V – 150A – 1500W, the output voltage of the transformer loaded on the three heating elements is 35V, the current is 180A, and it is adjusted by a thyristor (power regulator). The heating system and the control parameters of the temperature control meter are set as follows.