A heating element is a material or device that directly converts electrical energy into heat or thermal energy through a principle known as Joule heating.
The most important heating element characteristics are sufficient resistivity, high oxidation resistance, low-temperature coefficient of resistance, high toughness, and high melting point.
Widely used heating elements are nickel-chromium alloy, iron-chromium-aluminum alloy, molybdenum disilicide, and silicon carbide. These are followed by graphite and other refractory metals which generally have higher oxidation rates.
Aside from the heating element, a heater consists of the terminations, leads, insulation, packing, sheath, and seals. These heaters have various forms and configurations to suit a particular application.
Typical heater ordering specifications are the power or wattage, maximum operating temperature, type of process fluid, sheath material, and power supply (voltage and frequency).