Not all braking resistors are the same –
REOhm is the answer for modern inverter technology


Interesting facts about resistors

When an electric motor works as a generator (electromotive brake), the braking resistor protects the machine from a voltage rise in the DC link. At the same time, the reduction of current leads to a speed reduction of the engine and helps to brake the machine. REO braking resistors achieve a better heat dissipation and better dynamic behaviour by filling heat conducting material surrounding the wound body. REO resistors are short-circuit proof and self-extinguishing. They guarantee a high level of operational safety and are overload-proof in case of short-term loads for your applications (e.g. wind power engineering, railway engineering and automotive engineering).

The charging resistor is a current limiting resistor for the loading and discharge of capacitors and limits for example the in-rush current that flows into the intermediate circuit capacitor. The device must be laid out for a high level of single pulse energy and nominal voltage for this purpose. The inductance of the resistor also contributes to the limiting of the in-rush current, for this reason REO wire resistors are the correct choice.

Liquid cooling is a very efficient option that can reduce construction sizes by up to 80%. Liquid cooled resistors from REO are available with capacities from 1 to 100 kW. Cooling channels incorporated into the heat sink enable efficient cooling and the spatial separation of the current-carrying and liquid-carrying pipes – safe usage is guaranteed as a result.

REO damping resistors can absorb and temporarily store higher impulse loads. Thanks to the special winding technology, the wires of the damping resistors are separated spatially and therefore ensure a higher dielectric strength.
REO damping resistors are available in the protection classes IP00 to IP 65 and provide a high level of functional safety and service life.

UL resistors: The independent organisation “Underwriters Laboratories” (UL for short) has developed more than 1,300 safety standards. Many of these standards are in accordance with the American National Standards (ANSI) and, alongside the requirements for electrical safety for electrical items, they also often take into account additional requirements in relation to flammability.

High voltage resistors are subject to particular requirements as a result of their areas of application. The highest level of functional safety and service life paired with an extreme level of robustness against adverse environmental pressures are as a result absolutely essential.

REO high voltage resistors undergo the following tests:

  • Climatic fluctuation testing
  • Vibration and shock testing, simulated service life testing
  • Self-heating measurement
  • High voltage testing
  • Insulation measurement

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