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Cross Reference


Wire wound on mica plate coated with cement filled with quarzite sand and sealed with silicone plug

The RFD is a wire resistance wound on a mica cement coated plate, immersed in quartzite sand and placed in an anodized aluminium casing. The sealing is done by silicone elastomer and ensures IP54 protection. Versions are available with built-in winding. If interested, contact our sales department as it is not sold on the website. Version with thermal pad called the RFDT can be purchased on the website at the corresponding product page. The RFDV version, also sold on the website, involves cutting of the case at a 45° angle and mounting using the slots instead of the holes. The RFDVT version, also present on the store, involves cutting of the case at a 45° angle and thermal pad. The RFD can be purchased on the website in the version with UL marking.

Overview Table

Min Resistance
Max Resistance
Tolerance (%)
Rated Continuos Power (W)
Protection Degree (IP)
Not Inductive
Rated insulation voltage (V)
(Clarification on Voltage definitions.pdf)
Thermal switch

These options are available for this product:*

ohmic values out of range,special tolerance on resistance (2%, 1%),different cable lenght,heat-sink mounting
*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 RFD family has 8 models with power ratings from 50 W to 550 W and the ohmic value ranges between 0.25 Ω and 39K Ω. The RFD version marked UL has 6 models with power ratings from 25 W to 200 W and the ohmic value ranges between 1.5 Ω and 6K Ω. The maximum voltage of use varies depending on the model selected.

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 5 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, or the slots in case of the 45° angle version (RFDV). The provided cable that has not been stripped is used for electrical connection. There is no hole for the earth connection. The flat shape of this resistance makes it particularly easy to fit into electrical panels and dissipaters.


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