A series of dynamic breaking resistors, available from TTI, a leading distributor of passive components and connectors, offers a better pulse handling capability in a smaller package than traditional styles. Braking resistors are used to limit the voltage rise which can occur during a motor speed reduction phase, thus preventing damage to inverter electronics. TT Electronics Welwyn Components' WDBR enhanced planar pulse resistors are constructed using thick film on steel, which outperforms the equivalent wirewound resistor in terms of pulse handling capability in most cases. The integrated, high reliability, planar construction saves space, and a simple bolt fixing reduces heatsink installation costs. WDBR series resistors are available in two power ratings of 2 and 5kW, and standard ohmic values of 25R, 50R, 100R and 150R with a tolerance of 10%. Continuous power rating is up to 300W, and minimum dielectric withstand voltage is 2500V. Inductance is typically below <5H; maximum hot spot temperature is 365C. Resistors have a built-in failsafe overload mechanism, and are available with either push on tags or flying lead terminations. TTI Europe, High Wycombe, Bucks HP12 3YZ, UK.
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