RDF 750

RDF 750

Wire coiled inserted in ceramic tube and filled with quarzite sand, sealed by dielectric cement

The RDF is a resistance made in a winged dissipater with coiled wire inserted in perforated ceramic and filled with quartzite sand. The aluminium dissipater is sealed with dielectric cement and closed with appropriate plates; this ensures a minimum IP54 degree of protection. The RDFT model is identical to the RDF model with the addition of the thermal pad in this regard, see the relevant product page.

Overview Table

Min Resistance
Max Resistance
Tolerance (%)
Rated Continuos Power (W)
Protection Degree (IP)
Not Inductive
Maximum operating voltage permanent (V)
Thermal switch

These options are available for this product:*

ohmic values out of range,special tolerance on resistance (2%, 1%),different cable lenght *Options must be ordered separately. Contact Fairfild directly.

In what sectors is this resistance used?

The main areas of application are industrial automation and the energy sector.

For what types of applications is it used?

The product is used: as a dynamic braking resistor, such as capacitor charging and discharging resistance in RC circuits.

What are the electrical specifications?

The RDF family has 3 models with power ratings from 425 W to 550 W and the ohmic value ranges between 3.6 Ω and 510 Ω. The maximum voltage of use is 2000 V.

What are the overload conditions?

The resistance can be overloaded with respect to its nominal power based on the working cycle (insertion and rest time). For duration pulse less than one second, the overload permissible also depends on the ohmic value. For pulses of longer duration, the internal quartzite plays a decisive role in dissipating energy. See the section on overloads in the data sheet.

What is the temperature of the resistance?

The temperature of the resistance depends on the power that it will dissipate. Numerous factors influence the dissipation capacity; please consult our technical data sheet for detailed information. The graph on page 3 of the data sheet shows the relationship between the temperature on the casing and the power applied for a heating element placed horizontally.
The resistance can be installed horizontally or vertically, in this case it is necessary that the cables are facing downwards. For mounting, use the 4 holes available on the brackets. The provided cable that has not been stripped is used for electrical connection. There is also a hole for the earth connection. The dissipater provided is not anodized.


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