Bulk carbon resistors handle automotive stresses

The high pulse withstanding capability of the CCR series of carbon composition resistors offers automotive designers a compact solution for applications involving high voltages and high-energy pulses.

The high pulse withstanding capability of the CCR series of carbon composition resistors from Welwyn Components offers automotive designers a compact solution for applications involving high voltages and high-energy pulses.

With the decline of the hot moulded carbon composition resistor, Welwyn's CCR series now offers the industry a direct replacement resistor based on a bulk resistive element comprising carbon in a ceramic filler.

Due to the need for higher peak voltages, the CCR range is perfect for vehicle ignition system applications.

Advances in engine management and efficiency have led to changes in the way in which a vehicle ignition system operates.

New electronic management systems have replaced the old mechanically driven ignition with digital systems.

They employ microprocessor control capable of varying the ignition timing according to specific engine conditions.

In addition to this, new emission laws mean that engine efficiency is critical.

The standard CCR1 resistor offers a power rating of 1W at 25C and is made up of a solid rod of conductive composition material, which can be altered to produce different resistance values.

The entire rod conducts and so thermal mass is far higher resulting in a higher energy capability.

Typically the 1W CCR can handle 35J in contrast to 4J for a wire-wound resistor of similar dimensions.

In addition, the voltage capability is also higher.

With a typical resistance range of 220R-22K, TCR is 700ppm/C below 1K0 and 1000ppm/C above 1K0.

Resistance tolerance is from 5 to 20%.

CCR series resistors are colour coded and resistors with 20% tolerance have three bands indicating value.

Resistors with 5 and 10% tolerance have four bands indicating value and tolerance in accordance with IEC62.

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