Fluke A40 Current Shunt Kit

The Fluke A40 Current Shunt Kit is a precision resistor set designed to extend current measurement capabilities of multimeters and voltage-measuring instruments. These low-inductance coaxial shunts convert input current into measurable voltage drops across known resistances, enabling accurate AC and DC current measurements from milliampere to 100 ampere ranges. The kit supports both direct absolute current measurements and AC/DC current transfer applications in laboratory environments.

Technical Specifications

Current Range
Available configurations span 1 mA to 100 A, depending on series selection. The A40B Series provides 14 individual shunts covering six decades in 1-2-5 sequence. The A40 Series ranges from 10 mA to 5 A, while the A40A Series extends coverage with 10 A and 20 A shunts. Frequency Response
Usable from DC to 100 kHz across standard configurations. Extended operation to 100 MHz is supported with compatible equipment such as the Model 540B. Electrical Performance
Output voltage is nominally 0.8 V at rated current input. AC/DC difference specification is ±0.05%. The A40-200MA shunt achieves ±0.1% accuracy with a temperature coefficient of 0.005% per °C. A40B Series shunts exhibit stability better than ±5.0 µΩ/Ω over one year, with typical angular accuracy better than ±0.003° at 1 kHz. Resistance values vary by rating: the 100 A shunt is 8 milliohms; the 10 mA shunt is 80 ohms; the 1 mA shunt is 800 ohms with integrated buffer amplifier. Physical Design
Manganin alloy construction in low-inductance coaxial configuration ensures excellent self-heating power coefficient performance and minimal loading error.

Key Features

• Multiple series options (A40, A40A, A40B) for flexible range selection


• Programmed loading error defaults in compatible Fluke instruments


• Low temperature coefficient and exceptional long-term stability


• Coaxial design minimizes inductance effects


• Compatible with Fluke 5790B for automatic parameter programming

Typical Applications

• Direct measurement of absolute AC/DC currents in laboratory settings


• AC/DC current transfer measurements


• Extending measurement range of existing voltage-measuring equipment


• Precision current characterization across wide frequency spans

Compatibility & Integration Loading error information can be pre-programmed into compatible Fluke instruments including the 5790B, with empirical calibration data documented in the A40B Instruction Manual. Output voltage ratings and AC/DC difference parameters integrate directly into automated measurement workflows.