Ceramic Resistor Construction

The majority of the power wirewound resistors have a ceramic core and a ceramic coating to protect the winding.

Ceramic resistor construction.

Cement resistor only describes the appearance of common power resistors like that shown above. The construction of a resistor is shown in the below diagram. Wirewound resistors are very variable in construction and physical appearance. This mixture is then compressed into a cylindrical shape.

The ceramic coating combines a high insulation and physical protection with good heat dissipation. The construction of ceramic composition resistors concentrates nearly all of the component mass into the resistive element resulting in a rugged device with high energy capacity. However even this description is out of date. Then a thin film of resistive material is deposited this is typically metal oxide or a metal film again the resistor is fired.

The resistance is controlled based on the ratio of the insulator and conductor mixture. This resistor consists of two terminals like a normal resistor. Metal film resistors are produced by depositing a resistive element on a high grade ceramic rod. The construction of a carbon film resistor can be done by placing the carbon layer on a substrate of a ceramic.

The end connection electrode bases are then placed onto this and then this is fired to ensure they are robustly held in place. Their resistive elements are commonly lengths of wire usually an alloy such as nichrome nickel chromium or manganin copper nickel manganese wrapped around a ceramic or glass fibre rod or tube and coated in an insulating flameproof cement film. Typical resistance values are in the range from 1ω til 10 kω. Terminals are attached and the insulation coating is applied to the outside.

Tcr varies from 75 till 200 ppm c. They are most often wire wound resistors. Composition resistors are produced using a mixture of a finely ground insulator and conductor.