PWR Series Precision Wire Wound Resistors
Precision resistance wire wound on a ceramic core with multi-layer silicone coating
Power ratings: 0.5W, 1W, 2W, 3W, 5W, 7W and 10W
Resistance range: 0.1Ω to 100kΩ
Tolerance options: ±0.1%, ±0.25%, ±0.5%, ±1% and ±2%
TCR options: 20ppm/°C, 50ppm/°C and 90ppm/°C
Operating temperature range: −55°C to +200°C
Dielectric withstanding voltage: AC 500V for 1 minute
Short-time overload: 5× rated power for 5 seconds (up to 3W); 10× rated power for 5 seconds (above 3W)
Resistance values from E24 series; printed or colour-coded marking by power rating
RoHS compliant; axial leaded through-hole package for tape and reel or bulk supply
What are the PWR Series Precision Wire Wound Resistors?
The PWR is a precision axial leaded Wire Wound resistor designed for applications in which resistance accuracy, long-term stability, and a low temperature coefficient of resistance are more important than the general-purpose cost targets that govern standard Wire Wound types. Sharing the same silicone-coated ceramic-core axial construction as the general-purpose RW series, the PWR is differentiated by the grade of alloy wire selected, the precision of the winding process, and the tighter quality controls applied during manufacture — all of which combine to deliver the tighter tolerance and lower TCR values that precision circuit design demands.
The resistive element uses a carefully selected nickel-chromium or copper-nickel alloy wire whose composition is chosen for inherently low and predictable temperature dependence. Three TCR grades are offered: 20ppm/°C, 50ppm/°C and 90ppm/°C, covering the range from demanding metrology and calibration applications through to general precision circuit work. The tightest grade of 20ppm/°C means that a resistor operating across a 50°C temperature swing will deviate from its nominal value by no more than 0.1%, independent of initial tolerance — a level of thermal stability that film resistors of equivalent power rating cannot reliably achieve. The wire is wound on a ceramic core and the ends are welded to metal caps, giving a completely welded internal construction that eliminates the contact resistance instability associated with crimped terminations.
Tolerance grades of ±0.1%, ±0.25%, ±0.5%, ±1% and ±2% are available across the resistance range of 0.1Ω to 100kΩ, with power ratings of 0.5W, 1W, 2W, 3W, 5W, 7W and 10W. The multi-layer silicone coating is non-flammable and provides protection against humidity, solvents and thermal shock across an operating range of −55°C to +200°C. Maximum working voltage is defined by the square root of the product of rated power and resistance value. Dielectric withstanding voltage is AC 500V for one minute. Short-time overload is rated at five times the nominal power for five seconds for variants up to 3W, and ten times the nominal power for five seconds for variants above 3W, with resistance change limits consistent with the precision tolerances of each grade.
Long-term stability under sustained load is a defining characteristic of the Wire Wound construction: the resistance wire retains its calibrated value far more reliably than film elements under continuous thermal and electrical stress, and the resistance change over 1,000 hours of load life testing is held within tight limits appropriate to the selected tolerance grade. The PWR is manufactured to E24 preferred values as standard, with non-standard resistance values available on request. The series is supplied in standard axial taped packaging to support automated through-hole insertion and is also available in bulk format. STEP files are available for the major models to assist mechanical integration during PCB design.
PWR Series Precision Wire Wound Resistors Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
Model: PWR
Resistor type: Wire wound
Description: Precision wire wound
Power Rating: 0.5W~10W
Resistance (Ω): 0.1~100k
Tolerance (%): ±0.1, ±0.25, ±0.5, ±1, ±2
TCR (ppm/C): 20, 50, 90
Applications of the PWR Series Precision Wire Wound Resistors
Where RARA wire wound resistors are deployed in the field.
Precision instrumentation and measurement equipment — stable reference resistors, current-sensing elements and gain-setting networks in bench instruments, data loggers and signal analysers where resistance accuracy over temperature determines overall system error
Calibration standards and reference circuits — Wheatstone bridge completion resistors, decade resistance substitution boxes and precision voltage divider chains requiring long-term stability and low self-heating error at defined power levels
Weighing and force measurement systems — bridge completion and dummy-gauge resistors in load cells, strain gauge bridges and torque transducers where matched TCR and tight tolerance minimise temperature-induced zero drift
Analog signal conditioning — precision gain-setting, filter tuning and impedance-matching resistors in operational amplifier circuits, instrumentation amplifier stages and active filter networks where component accuracy directly limits achievable noise and linearity
Power supply regulation and feedback — output voltage sensing, reference division and feedback network resistors in precision linear regulators and DC-DC converters where drift in the resistive network directly translates to output voltage error
Medical and laboratory instrumentation — current-limiting, biasing and signal path resistors in diagnostic equipment, patient monitoring systems and analytical instruments where stable, repeatable resistance values are required across the full operating temperature range
Automotive and industrial control systems — precision sensing and control resistors in motor drive feedback loops, resolver-to-digital conversion circuits and process control instrumentation where thermal stability must be maintained under continuous elevated-temperature operation
Defence and aerospace electronics — reference and timing resistors in guidance, communication and power management circuits operating across wide temperature ranges and requiring long-term resistance stability without recalibration
Related Products of the PWR Series Precision Wire Wound Resistors
Model: SMW
Resistor type: Wire wound
Description: Power chip
Power Rating: 2W, 3W, 5W
Resistance (Ω): 0.1~680
Tolerance (%): ±1, ±2, ±3, ±5, ±10
TCR (ppm/C): 200
Model: FWR
Resistor type: Wire wound
Description: Fusible
Power Rating: 1W, 2W, 3W, 5W
Resistance (Ω): 0.1~200
Tolerance (%): ±5
TCR (ppm/C): 300
Model: RW
Resistor type: Wire wound
Description: Wire wound
Power Rating: 0.5W~10W
Resistance (Ω): 0.1~680
Tolerance (%): ±1, ±2, ±3, ±5, ±10
TCR (ppm/C): 260 max.
Model: RQA
Resistor type: Wire wound
Description: Ceramic encased
Power Rating: 5W~20W
Resistance (Ω): 0.1~100k
Tolerance (%): ±5, ±10
TCR (ppm/C): 260, 400
Why Choose RARA Wire Wound Resistors
What sets RARA apart for engineers and procurement managers in industrial and automotive markets.
01
Widest Design Range
From 0.5W precision types to 12kW edge wound assemblies — one wire wound product family covering precision, ceramic-encased, fusible, non-flammable, and high-power variants.
02
Precision Available
The PWR series delivers ±0.1% tolerance and TCR as low as 20 ppm/°C — precision wire wound performance for instrumentation and measurement circuits.
03
Automotive Qualified
The AQL ceramic-encased series is AEC-Q200 qualified for automotive-grade reliability in EV battery management, HVAC, and powertrain applications.
04
Global Track Record
Trusted by Siemens, Rockwell, Toshiba, Schneider Electric, LG, and Hanwha — a customer base built on decades of consistent, certified performance.
