RH/FRH 15-50W Series Metal Clad Resistors
Wire wound resistive element in aluminium-housed, cement-moulded construction
RH 25C: 20W rated power on heatsink (178 × 127 × 51 × 1mm), 8W in free air
RH 50C: 50W rated power on heatsink (305 × 305 × 2mm), 10W in free air
Resistance range 0.27Ω to 25kΩ inductive and 0.1Ω to 10kΩ non-inductive (RH 25C)
Resistance range 0.68Ω to 50kΩ inductive and 0.2Ω to 20kΩ non-inductive (RH 50C)
Tolerance options ±0.1%, ±0.5%, ±1.0%, ±2.0% and ±5.0%
TCR ±40 to ±100ppm/°C; ±20ppm/°C available on request
Operating temperature range −55°C to +250°C
Insulation resistance 20MΩ minimum
Dielectric strength AC 1000V for 1 minute
Chassis-mount aluminium housing for direct heatsink coupling
Completely welded construction; RoHS compliant
What are the RH/FRH 15-50W Metal Clad Resistors?
The RH 25C and RH 50C are high-power metal clad wire wound resistors sharing the same aluminium-housed, cement-moulded platform, differentiated by their power rating and associated heatsink requirements. Both models are built on a completely welded aluminium housing that provides mechanical rigidity and efficient heat transfer to a chassis or external heatsink. The RH 25C delivers a continuous rated power of 20W when mounted on a 178 × 127 × 51 × 1mm heatsink, or 8W in free air, while the RH 50C is rated at 50W on a 305 × 305 × 2mm heatsink and 10W in free air. This scalable power architecture allows engineers to select the appropriate model for the thermal budget and footprint of a given assembly without changing the underlying component family or ordering process.
The resistance range of the RH 25C spans 0.27Ω to 25kΩ in the standard inductive configuration and 0.1Ω to 10kΩ in the non-inductive variant. The RH 50C extends these ranges to 0.68Ω–50kΩ inductive and 0.2Ω–20kΩ non-inductive, providing impedance coverage for a broad set of industrial power and control circuits. Tolerance options from ±0.1% to ±5.0% are available, with the tightest grades accessible from 1Ω upward. Temperature coefficient of resistance is offered at ±40, ±50, ±100 and ±200ppm/°C depending on resistance value and winding type, with a ±20ppm/°C option available on request for precision-critical applications. The operating temperature range extends from −55°C to +250°C, reflecting the thermal robustness of the wire wound element and cement encapsulation.
Both the RH 25C and RH 50C are available with inductive or non-inductive windings, the non-inductive variant being identified by the suffix ‘N’ in the part number. The non-inductive winding suppresses inductive reactance at higher frequencies, making these models suitable for switching, snubber, and damping applications where a conventional wire wound construction would introduce impedance errors. Key electrical characteristics include an insulation resistance of 20MΩ minimum, dielectric strength of AC 1000V for one minute, and short-time overload capability of five times rated power for five seconds. The components are qualified against moisture resistance, thermal shock, vibration, and load life to 1000 hours. The cement-moulded construction within the aluminium housing conforms to RoHS requirements and the completely welded enclosure provides a high degree of environmental protection suited to harsh industrial conditions.
RH/FRH 15-50W Metal Clad Resistors Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
Model: RH, FRH
Resistor type: Metal clad resistor
Description: Aluminum housed, chassis mounted
Power Rating: 15W, 20W, 50W
Resistance (Ω): 0.1~2M
Tolerance (%): ±0.1, ±0.5, ±1, ±5, ±10
TCR (ppm/C): 40, 50, 100, 200
Applications of the RH/FRH 15-50W Metal Clad Resistors
Where RARA metal clad resistors are deployed in the field.
Motor drive and variable-speed drive circuits — braking chopper and DC bus resistors
Power converter snubber and IGBT/GTO gate circuits — non-inductive transient energy absorption
Electric power conversion systems — dynamic braking and regenerative discharge networks
Industrial power supplies — current limiting, soft-start and inrush protection resistors
UPS and power conditioning equipment — load banks and battery discharge networks
Inverter and converter assemblies — chassis-mounted damping and series protection resistors
High-frequency switching circuits — non-inductive winding variant for snubber and filter stages
Test and measurement equipment — precision load resistors in tight-tolerance grades
Industrial automation and control panels — compact high-power dissipation elements
Renewable energy systems — dump load and crowbar resistor assemblies
Automotive and transportation power electronics — chassis-mounted resistors in harsh environments
Telecommunications power equipment — high-power filtering and protection resistors
Related Products of the RH/FRH 15-50W Metal Clad Resistors
Model: RH10C
Resistor type: Metal clad resistor
Description: Metal clad cement encased
Power Rating: 10W
Resistance (Ω): 0.1~6k
Tolerance (%): ±0.5, ±1, ±2, ±5
TCR (ppm/C): 260 Max.
Model: IRB
Resistor type: Metal clad resistor
Description: Metal clad economy
Power Rating: 60W~120W
Resistance (Ω): 0.1~1.3k
Tolerance (%): ±2, ±5, ±10
TCR (ppm/C): 260 Max.
Model: URH
Resistor type: Metal clad resistor
Description: UL Aluminum housed, chassis mounted
Power Rating: 20W-100W
Resistance (Ω): 0.1~50k
Tolerance (%): ±1, ±2, ±5
TCR (ppm/C): 30, 50, 100, 200
Model: IRS
Resistor type: Metal clad resistor
Description: Slim profile, aluminum housed, chassis mounted
Power Rating: 30W, 50W
Resistance (Ω): 1~500
Tolerance (%): ±0.5, ±1, ±2, ±5, ±10
TCR (ppm/C): 260 Max.
Why Choose RARA Metal Clad Resistors
What sets RARA apart for engineers and procurement managers in industrial and automotive markets.
01
Automotive Qualified
AEC-Q200 tested models and IATF 16949 certification for EV and automotive powertrain applications. Trusted by GM Korea, Tesla, and Proterra.
02
STEP Files Included
3D STEP files available for core models, supporting ECAD/MCAD integration and thermal management simulation in your design workflow.
03
Wide Power Range
A single product family spanning 10W to 8.5kW means you can source across a project from one qualified, certified supplier.
04
Global Track Record
Deployed by Siemens, Rockwell, Toshiba, Schneider Electric, LG, and Hanwha — a customer list built on decades of consistent performance.
