IRHF Series Precision Metal Clad Shunt Resistors

What are the IRHF Series Precision Metal Clad Shunt Resistors?

The IRHF is a high-power precision shunt resistor built using four-terminal (Kelvin) construction on a metal clad substrate. The four-terminal architecture physically separates the current-carrying bus connections from the voltage-sense terminals, eliminating the contact resistance errors inherent in conventional two-terminal measurements. This makes the IRHF capable of delivering accurate millivolt-level output signals even at high currents, without the measurement uncertainty introduced by terminal resistance or connection quality.

The series spans rated currents from 30A (IRH 80F) up to 500A (IRH 800F), with resistance values ranging from 0.125mΩ to 3.333mΩ and rated output voltages typically at 50mV or 100mV, depending on model and current rating. Tolerance options of ±0.1%, ±0.5%, and ±1.0% are available across the range. The temperature coefficient of resistance (TCR) is a maximum of ±15ppm/°C over the 20°C to 60°C range for standard models, with a 30ppm/°C variant also specified. This tight TCR combined with close initial tolerance ensures that resistance drift over the operating temperature range remains within the accuracy budgets of demanding measurement systems.

The metal clad substrate provides both mechanical rigidity and efficient heat spreading, enabling the IRHF to sustain its rated continuous current without active cooling in most mounting configurations. The heavy copper terminals are designed for direct attachment to a current bus bar, with separate flexible wire connections made to the voltage sense terminals. This installation method minimises lead resistance variation and simplifies integration into existing busbars or test fixtures without requiring circuit redesign.

The low-inductance construction of the IRHF ensures that transient current events are accurately reflected in the output voltage without ringing or phase error, which is important in battery test and power conversion applications where fast current slew rates are common. Electrical isolation between the resistive element and the mounting surface is confirmed by a minimum insulation resistance of 100MΩ at DC 500V and a dielectric withstanding voltage of AC 500V for one minute, both of which support deployment in line-voltage and high-voltage battery systems. UL-certified versions designated as ULH models are available for applications requiring third-party safety certification.

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: 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

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: LT
Resistor type: Current sensing
Description: High power precision
Rated Current: 50A~500A
Resistance (Ω): 0.2m~2m
Tolerance (%): ±0.1, ±0.5, ±1
TCR (ppm/C): 30

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