RH, RHF Series Precision High Power Wire Wound Resistors
Precision wire wound resistive element with cement-moulded aluminium housing
Power rating 1W to 50W — chassis or heatsink mounted for maximum thermal performance
Resistance range 1mΩ to 600kΩ — spanning low-value current sensing to high-value feedback
RH: standard body with axial leads — RHF: flanged chassis-mount variant
Operating temperature range −55°C to +250°C
Tolerance options ±0.01% to ±1%
TCR options 30, 50 and 100 ppm/°C
Long-term stability under full rated load across thousands of operating hours
Non-inductive winding options available for high-frequency and fast-switching applications
Suitable for continuous-duty power sensing, regulation feedback and precision load circuits
What are the RH, RHF Series Precision High Power Wire Wound Resistors?
The RH and RHF are precision high-power wire wound resistors combining resistance accuracy and long-term stability with continuous power ratings from 1W to 50W, making them the highest-power members of RARA Electronics’ precision resistor portfolio. Where the signal-level precision wire wound series — 5G10, 8G16/8G24, GG102, AX, and CE-CL-T — are rated in fractions of a watt and are designed exclusively for measurement and reference applications, the RH/RHF series bridges the gap between precision and power, serving circuits where the resistor must simultaneously carry significant continuous current, maintain an accurately known resistance value, and remain stable across the full operating temperature and load lifetime of the equipment. With tolerances as tight as ±0.01% and TCR options down to 30 ppm/°C, the RH/RHF delivers a level of accuracy at high power that is unavailable from standard power resistors, which typically offer only ±5% tolerance and TCR values of several hundred ppm/°C.
Construction uses a precision wire wound resistive element encapsulated in cement moulding within an aluminium housing. The aluminium body serves as both mechanical protection and the primary thermal path — heat generated by the resistive element conducts through the cement fill to the housing and from there directly to the chassis or heatsink surface to which the resistor is mounted. This construction allows the full 50W power rating to be achieved when mounted on an adequate heatsink, while lower ratings apply in free air where convection alone removes the dissipated heat. The operating temperature range of −55°C to +250°C reflects the robustness of the cement-and-aluminium construction, which is unaffected by the thermal cycling and elevated ambient temperatures encountered in industrial and automotive power electronics environments.
The resistance range of 1mΩ to 600kΩ is exceptionally broad for a precision high-power series and encompasses both the milliohm values required for high-current sensing applications and the kiloohm values required for feedback dividers, load resistors, and output voltage setting networks in power supplies. The RH and RHF variants share the same resistive element and electrical specifications; the RHF adds a flanged mounting tab that simplifies direct chassis attachment without a separate bracket, making it the preferred choice for panel-mount and cabinet installations where installation speed and mechanical security both matter. Non-inductive winding options are available across the resistance range for applications where standard wire wound construction would introduce unacceptable inductive reactance at the switching frequencies of the circuit.
The RH/RHF is classified within RARA Electronics’ high-power precision category alongside the RMF four-terminal resistor and the TNP10P/20P heatsinkable film resistor. All three series address the requirement for precision-at-power, but the RH/RHF occupies the top of the power range at up to 50W continuous and offers the widest resistance span of the three. RARA Electronics holds ISO 9001 and IATF 16949 certifications, and the RH/RHF is manufactured to the quality standards relied upon by major industrial, power electronics, and automotive customers globally, including Toshiba, Siemens, Rockwell, LG, and Schneider Electric.
RH, RHF Series Precision High Power Wire Wound Resistors Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
Model: RH/RHF
Resistor type: Precision
Description: High power wire wound
Power Rating: 1W~50W
Resistance (Ω): 1m~600k
Tolerance (%): ±0.01, ±1
TCR (ppm/C): 30, 50, 100
Applications of the RH, RHF Series Precision High Power Wire Wound Resistors
Where RARA precision resistors are deployed in the field.
Power supply output voltage setting and regulation feedback — precision resistor dividers in the feedback loops of linear regulators, switching mode power supplies, and laboratory bench power supplies where the output voltage is set by the ratio of two resistors and where thermal drift or long-term resistance change in either resistor produces a proportional output voltage error; the RH/RHF provides the combination of tight tolerance, low TCR, and wattage rating required when the feedback resistors must carry significant continuous current
High-current sensing and measurement — series sense resistors in motor drive phase legs, battery management system charge and discharge loops, welding equipment current monitors, and industrial power metering circuits where milliohm-range resistance values at multi-watt power ratings are required and where the tolerance of the sense element directly determines the accuracy of the current measurement at system level
Motor drive and variable-speed drive control circuits — precision current feedback resistors and torque reference resistors in DC and AC servo drive analogue control loops where continuous motor current produces sustained power dissipation in the sense element and where the resistance value must remain within tolerance across the full thermal rise associated with that dissipation
Precision electronic load circuits and constant-current sinks — series and parallel sense resistors in programmable electronic loads, battery test systems, and power supply characterisation equipment where accurate knowledge of the load resistance or sense resistance at multi-watt dissipation levels is fundamental to the calibration accuracy of the instrument
Power converter and inverter snubber networks — non-inductive RH/RHF resistors in RC snubber circuits across power switching devices in motor inverters, solar inverters, and UPS systems where repetitive transient energy dissipation requires a power-rated component and where the precision tolerance ensures consistent snubber time constants across production units
Industrial and laboratory power dissipation loads — precision dummy load resistors in power supply burn-in test rigs, transformer secondary load banks, and regulated power source characterisation fixtures where accurate and stable load resistance at high continuous power is required to maintain controlled test conditions throughout extended test sequences
Defence and aerospace power electronics — precision high-power resistors in avionic power supply feedback networks, missile electronics power conditioning modules, and ground support equipment power regulators where the wide operating temperature range of −55°C to +250°C, tight tolerance, and long-term stability under continuous load meet the combined environmental and accuracy demands of mission-critical power circuits
Automotive and electric vehicle power electronics — precision sense and feedback resistors in on-board charger power stages, DC-DC converter feedback loops, and battery pack balancing circuits qualified to IATF 16949 standards, where the combination of tight tolerance, low TCR, chassis-mount construction, and 50W power rating meets the simultaneous accuracy and thermal dissipation demands of automotive power conversion at full rated current
Renewable energy and power conditioning systems — precision current sense and output feedback resistors in solar inverter power stages, wind turbine converter modules, and grid-tied energy storage systems where continuous outdoor operation across wide ambient temperature swings demands both the thermal robustness of the aluminium-housed cement construction and the resistance stability of a precision wire wound element
Industrial calibration and reference load equipment — precision power resistors in calibrated load banks, resistance reference standards at elevated power levels, and high-power substitution boxes used in the calibration and verification of power measurement instruments, energy meters, and protection relay test equipment where the resistance value must be known and stable to better than 0.1% across the full range of operating temperatures and current levels applied during the calibration procedure
Related Products of the RH, RHF Series Precision High Power Wire Wound Resistors
Model: RMF
Resistor type: Precision
Description: High power 4 terminal
Power Rating: 10W
Resistance (Ω): 0.5~200
Tolerance (%): ±0.1~±5
TCR (ppm/C): 5, 10, 15, 20, 30
Model: 400 Series
Resistor type: High Voltage
Description: Precision, Non-Inductive
Low TCR
Power Rating: 3.8W~20W
Supply voltage: 15kV~90kV
Resistance (Ω): 1k~1T
Tolerance (%): ±0.05 to ±10
TCR (ppm/C): 5, 10, 15, 25, 50, 100
Model: LM
Resistor type: High precision
Description: Plate
Power Rating: 1/8W-1W
Resistance (Ω): 500k~1G
Tolerance (%): ±0.1, ±0.25, ±0.50
TCR (ppm/C): 25, 50, 100
Model: 5340
Resistor type: Precision
Description: Calibration
Power Rating: 0.5W
Resistance (Ω): 1m~1k
Tolerance (%): ±0.01
TCR (ppm/C): 5
Why Choose RARA Precision Resistors
What sets RARA apart for engineers and procurement managers in industrial and automotive markets.
01
Extreme Accuracy
Tolerances as tight as ±0.005% and TCR as low as 3 ppm/°C — across metal film, thin film chip, wire wound, and MELF construction types to suit every precision circuit requirement.
02
Long-Term Stability
Precision resistors are only useful if they stay accurate. RARA precision types are engineered for extended load life — maintaining resistance within specification over thousands of hours of operation.
03
Full Technology Range
From 1/32W SMD thin film chips to 50W high-power precision wire wound types — one precision resistor family covering every power level and form factor from a single ISO-certified supplier.
04
Global Track Record
Trusted by Toshiba, Siemens, Rockwell, LG, and Schneider Electric — deployed in instrumentation, medical, and industrial measurement systems across six continents.
