400 Series Precision Non-Inductive Low TC High Voltage Resistors
Ruthenium oxide thick film resistive element on 96% Al₂O₃ ceramic core
Proprietary non-inductive resistance system and design
Eight body sizes: 400.2, 400.3, 400.4, 400.5, 400.7, 400.10, 400.12, 400.15
Power rating 3.8W to 20W
Maximum operating voltage 15kV to 90kV depending on body size
Resistance range 1kΩ to 100GΩ standard; to 1TΩ on request
TCR options 5, 10, 15, 25, 50, and 100 ppm/°C (10 ppm/°C available to 10GΩ; 25 ppm/°C to 100GΩ)
Tolerance options ±0.05%, ±0.1%, ±0.25%, ±0.5%, ±1.0%, ±2.0%, ±5.0%, ±10.0%
Voltage coefficient of resistance (VCR) as low as <0.04 ppm/V on 400.15
Operating temperature −55°C to +225°C; extended range to 350°C available
Insulation resistance >10,000 MΩ at 500V, 25°C, 75% RH
Load life ΔR/R <0.1% typical, 0.20% maximum after 1000 hours at rated power
Gold plated lead material
Silicone conformal coating standard; epoxy conformal coating (E type) available
Polyimide or epoxy coating recommended for oil and potted applications
What are the 400 Series Precision Non-Inductive Low TC High Voltage Resistors?
The 400 Series is a range of precision, non-inductive high voltage resistors developed to meet the temperature stability and accuracy requirements of high-precision, high-voltage systems. Eight body sizes are offered — 400.2 through 400.15 — spanning power ratings from 3.8W to 20W and maximum operating voltages from 15kV on the smallest body up to 90kV on the largest. The resistive element is ruthenium oxide deposited on a 96% alumina ceramic core using a proprietary non-inductive winding and deposition system, a construction that eliminates the inductive reactance of wirewound alternatives while achieving the low temperature coefficients and exceptional voltage stability that precision high-voltage applications demand. Standard resistance values run from 1kΩ to 100GΩ across all models, with values to 1TΩ available on request.
Six TCR grades are offered — 5, 10, 15, 25, 50, and 100 ppm/°C — referenced to 25°C with ΔR taken at +125°C, providing a level of thermal precision that spans from the most demanding metrology and scientific instrument duties at 5 ppm/°C down to general high-voltage industrial use at 100 ppm/°C, all within a single product family and form factor. Tolerance options extend as tight as ±0.05% for precision divider and reference duties, through to ±10% for general applications. The voltage coefficient of resistance is a defining parameter of the series: it falls as low as <0.04 ppm/V on the 400.15 body for resistance values up to 5GΩ, and remains below <0.08 ppm/V in the upper resistance sub-range of the same model. This controlled VCR ensures that resistance values remain stable as operating voltage varies across the working range — a critical property at the gigaohm and teraohm values where voltage-induced resistance shift becomes a primary source of measurement and regulation error.
All 400 Series resistors are encapsulated in a high-temperature silicone conformal coating as standard, with an epoxy conformal coating (E-type) available as an alternative for specific environmental requirements. For use in oil-filled or potted assemblies, a dual polyimide coating or the epoxy E-type variant is recommended. The operating temperature range of −55°C to +225°C is standard, with an extended range to 350°C available on request, supporting deployment in the most thermally demanding environments. Reliability characteristics are specified at ΔR/R <0.1% typical and 0.20% maximum across load life at rated power for 1000 hours, thermal shock per MIL-STD-202 Method 107, moisture resistance per MIL-STD-202 Method 106, and overload at 1.5 times rated power for 5 seconds — in each case meeting the same 0.20% maximum drift limit, confirming consistent performance integrity across all stress modes.
400 Series Precision Non-Inductive Low TC High Voltage Resistors Specifications
A practical overview for engineers and procurement teams evaluating resistive solutions.
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
Applications of the 400 Series Precision Non-Inductive Low TC High Voltage Resistors
Where RARA high voltage resistors are deployed in the field.
Travelling wave tube (TWT) amplifier power supplies — precision voltage division and feedback resistors in the multi-stage high voltage supplies of TWT amplifiers used in satellite communications, radar, and electronic warfare systems, where resistance stability under continuous kilovolt-level stress directly determines output accuracy.
Electron microscopes and focused ion beam instruments — accelerating voltage divider chains and deflection supply feedback networks where the 5 ppm/°C TCR grade and sub-0.1 ppm/V VCR are essential for nanometre-level beam stability and imaging resolution.
X-ray systems and radiographic equipment — tube voltage sensing, regulation feedback, and monitoring dividers in medical, dental, and industrial X-ray generators operating at tens of kilovolts, where long-term load life stability and tight tolerance maintain dosage consistency.
High resolution CRT displays and cathode ray tube power supplies — anode and focus voltage divider networks in high-resolution display systems requiring stable kilovolt-level potentials to maintain geometry, focus, and brightness accuracy.
Geophysical and downhole instrumentation — high-impedance sensing and reference resistors in well-logging tools, seismic acquisition equipment, and subsurface measurement systems operating across wide temperature excursions, benefiting from the extended operating range to 350°C.
Precision high voltage calibration and metrology instruments — reference dividers, attenuator networks, and calibration source components where the ±0.05% tolerance and 5 ppm/°C TCR deliver measurement uncertainty that approaches dedicated metrology standards.
High voltage laboratory and test equipment — stable high-resistance elements in oscilloscope high-voltage probes, insulation testers, dielectric analysers, and impulse calibration sources where non-inductive construction and low VCR are prerequisites for accurate waveform reproduction.
Particle accelerator and nuclear instrumentation — high-stability, high-voltage divider and bias resistors in accelerator beam optics, detector bias supplies, and spectrometer power stages operating at sustained high voltages in environments with wide thermal variation.
Related Products of the 400 Series Precision Non-Inductive Low TC High Voltage Resistors
Model: HVI
Resistor type: High Voltage
Description: Thick film Tubular
Power Rating: 1W~6W
Supply voltage: 4kV~30kV
Resistance (Ω): 100k~1G
Tolerance (%): ±1
TCR (ppm/C): 25
Model: UHV
Resistor type: High Voltage
Description: High Voltage and Ohm
Power Rating: 0.5W~3W
Supply voltage: 3kV~14kV
Resistance (Ω): 1K~2G
Tolerance (%): ±1, ±2, ±5, ±10
TCR (ppm/C): 25~500
Model: HVE
Resistor type: High Voltage
Description: Thick film Tubular
Power Rating: 2.5W~20W
Supply voltage: 4.8kV~45kV
Resistance (Ω): 200~10G
Tolerance (%): ±1, ±5, ±10
TCR (ppm/C): 100
Model: HVR
Resistor type: High Voltage
Description: High Voltage Tubular
Power Rating: 8W~300W
Supply voltage: 25kV~80kV
Resistance (Ω): 10~1G
Tolerance (%): ±1, ±2, ±5, ±10
TCR (ppm/C): 50~1000
Why Choose RARA High Voltage Resistors
What sets RARA apart for engineers and procurement managers in industrial and automotive markets.
01
Widest Voltage Range
From 1kV SMD chip types to 90kV precision planar resistors — RARA's high voltage lineup covers more of the voltage spectrum than virtually any single supplier.
02
Extreme Precision
The 400 Series delivers ±0.05% tolerance and 5 ppm/°C TCR — precision that rivals dedicated metrology components, available at high voltage ratings up to 90kV.
03
5 Form Factors
SMD, axial, radial, tubular, and planar configurations give design engineers the right package for board-level, through-hole, or chassis-mounted high voltage circuits.
04
Global Track Record
Trusted by Toshiba, Siemens, Rockwell, and Schneider Electric — deployed in medical, industrial, and telecom high voltage systems across six continents.
