UHPS Series Ultra High Power Precision Shunt Resistors

What are the UHPS Series Ultra High Power Precision Shunt Resistors?

The UHPS is RARA Electronics’ ultra high power precision 4-terminal shunt resistor, engineered for applications that demand both extreme current handling and high measurement accuracy simultaneously. Rated at 100W continuous power on a suitable heat sink and capable of sustaining currents up to 707A, the UHPS addresses the growing requirement for high-power precision current sensing in modern power electronics, energy storage systems, and laboratory equipment.
A current sensing resistor — also called a shunt resistor — is a precision low-resistance component inserted in series with a load circuit to measure electrical current flow without interrupting the load path. By accurately measuring the small voltage drop that develops across the known resistance using Ohm’s Law (V = I × R), the current through the circuit can be precisely determined. The fundamental requirements for an effective shunt resistor are very low resistance to minimise power dissipation and voltage drop, tight tolerance for measurement accuracy, and low TCR so that the resistance — and therefore the measurement — stays stable as the component heats up under load.

The UHPS takes this further with its 4-terminal (Kelvin) connection design. In a conventional 2-terminal resistor, the same terminals carry both the load current and the sense voltage, meaning any resistance in the leads or contact points adds directly to the measured value. The 4-terminal architecture uses dedicated current-carrying terminals and independent sense voltage terminals, completely isolating the voltage measurement from the current path. This is especially critical in the sub-milliohm range where lead resistance errors would otherwise dominate and corrupt the measurement.

The resistance range spans 0.2mΩ to 1mΩ, with tolerance options as tight as ±0.05% and TCR options of ±3, ±5 and ±10 ppm/°C. Short-term stability is specified at ΔR ≤±0.1% for one hour at maximum current load with the terminal and copper flange temperature held at or below +50°C. The copper flange mounting interface enables efficient heat transfer to an external heat sink, allowing sustained continuous operation at maximum rated power. Dielectric withstanding voltage is rated at 500V AC for 60 seconds at a maximum leakage current of 2mA, confirming suitability for use in high-voltage industrial and power conversion environments.

Model: UHPS
Resistor type: Current sensing
Description: Ultra high power precision
Power Rating: 100W
Rated Current: 707A max.
Resistance (Ω): 0.2m~1m
Tolerance (%): ±0.05, ±0.1, ±0.5, ±1
TCR (ppm/C): 3, 5, 10

More Information

Model: LPS
Resistor type: Current sensing
Description: Low cost precision
Rated Current: 200A~300A
Resistance (Ω): 0.1666m~0.25m
Tolerance (%): ±0.5, ±1
TCR (ppm/C): 15, 30

Model: IRHF
Resistor type: Current sensing
Description: High power precision
Rated Current: 30A~500A
Resistance (Ω): 0.2m~3.333m
Tolerance (%): ±0.1, ±0.5, ±1
TCR (ppm/C): 15, 30

Model: HPS
Resistor type: Current sensing
Description: High power precision
Power Rating: 250W
Rated Current: 387A max.
Resistance (Ω): 1m~100m
Tolerance (%): ±0.05, ±0.1, ±0.5, ±1
TCR (ppm/C): 3, 5, 10

Model: PSS
Resistor type: Current sensing
Description: High power precision
Power Rating: 100W
Rated Current: 1400A max.
Resistance (Ω): 50u~1m
Tolerance (%): ±0.1, ±0.5, ±1
TCR (ppm/C): 3, 5, 10