Why should the resistance of electric heater wire be high

The resistance of heating wire of electric heater is selected according to the set power. The greater the power, the smaller the total resistance.

The resistivity of electric heating wire has a proper range. If the resistivity is too large or too small, it needs very short or very long, very thin or very thick electric wire, so it is difficult to manufacture and use electric heater with large and small power.

An important parameter of electric heating wire is the surface power. If the resistivity is too high, the surface power will be high after a certain current is applied. So small power electrical appliances, choose small diameter and small current, but the size of the current depends on the size of the resistance, the length and diameter of the heating wire is calculated.

Large industrial electric furnace using electric heating belt is to increase the surface area to ensure that the surface power will not exceed the standard. At the same time, in order to ensure high power, it is necessary to have enough current, so that the length, cross-sectional area and shape of each heating strip are comprehensively considered.

Therefore, the electric wire (belt) used in electric heater, when designing an electric heater, needs many factors of power.

The power required by this electric heater

The allowable surface power of the material, the cross-sectional area of the heating wire (tape), the length of the electric heating wire, and the shape of the electric heating wire (straight line, spiral, broken line, winding, etc.) etc.

Some special electric heaters, such as electric blankets, require large heat dissipation area and low unit power. If the usual Ni Cr and Fe Cr al heating wires are used, the electric wires with thin cross-section are needed, which can not be made at all. Therefore, the electric blanket is made of manganese copper wire. The resistivity of manganese copper wire is much smaller than that of iron chromium aluminum, so as to have enough length.

In fact, the resistance required by this kind of electric heater and the thickness and length of the heating wire can be seen at a glance by comparing the size of light bulbs.