ELECTRONICS: TT electronics IRC has developed a series of planar power resistors for hybrid electric vehicles. Designated the WDBR Series, the planar thick-film resistors carry surge power ratings up to 7kW and feature a steel substrate that provides direct transfer of thermal energy to an external heat sink.
The WDBR Series resistors can also be used in bleeder circuits to safely absorb excess energy that results when alternative energy systems such as fuel cells or onboard generators are switched off. The resistor’s planar geometry also provides smaller size, less weight and lower cost than conventional resistor technology.
The WDBR Series planar power resistors are rated for 0.5, 1.0, 2, 3, 5 and 7kW (maximum pulse power rating). Standard resistance values include 12, 22, 47, 100 and 150Ω, with tolerances to ±10 percent (custom resistance values and tolerances are also available). Minimum dielectric withstanding voltage is specified at 2,500V dc. Inductance values range from less than 3µH to less than 6µH.
The thick film resistive element is printed on an insulated stainless-steel substrate, with a high temperature overglaze for protection. The closely matched thermal expansion coefficient between the steel substrate and the dielectric film enable the WDBR Series resistors to withstand severe temperature cycling (up to 400C). Dimensions for the resistor range from 1.94 x 1.41 inch to 4 x 6 inch, with substrate thickness of either 0.035 or 0.059 inch.
-Edited by Kelsey Anderson