The A40B Precision Current Shunt Set consists of 14 low-inductance coaxial current shunts, adapters and connectors, and a rugged transit/storage case. Designed for currents from 1 mA to 100A, the current shunts are for laboratory use in making directly measured absolute ac or dc current measurements as well as ac/dc current transfer measurements. They exhibit outstanding resistance value stability, with an excellent self-heating power coefficient, and a low temperature coefficient. With all of these characteristics combined, the shunts offer direct measurement of current from dc to 100 kHz with higher accuracy than previous commercially available shunt technology. Now precision measurements can be made in a single step process rather than by more complex traditional ac/dc transfer methods.

Application
The wide range of shunt values permit measuring from 0.1mA to 100 Amps. The physical construction and the components used in the current shunts ensure that the frequency response is very flat (amplitude displacement error relative to dc resistance). Also the phase displacement at 100 kHz is small enough to be neglected in all but the highest accuracy measurements. Combined with excellent dc resistance stability, the shunts can be used to directly measure current through their full bandwidth. This simplifies precision ac current measurements as the complex ac/dc transfer measurement process will no longer be necessary for many precision current measurement applications. These characteristics make the A40B shunts ideal for traditional precision current applications such as calibrator verification. Also, the wide current range allows verification of high current transconductance amplifiers. The low phase shift error is critical for measurement of non sinusoidal wave shapes, as found in power quality or sampling digital wattmeter measurement applications.

Technical overview
The shunts come in four different sizes. The full set includes:

four fully enclosed shunts: 1 mA, 10 mA, 20 mA, 50 mA five small size radial shunts: 100 mA, 200 mA, 500 mA, 1 A, 2 A three medium size radial shunts: 5A, 10 A, 20 A two large size radial shunts: 50 A, 100 A

Voltage output is nominally 0.8 volts for the nominal rated current input. The output is measured by a voltmeter or detector, such as precision voltmeters, ac measurement standards, ac/dc transfer standards, or thermal voltage converters, fitting them to a wide variety of metrology applications.

The radial style shunt design gives high performance with minimum external magnetic fields. Plus, the open nature of the physical design maximizes air flow so the shunts have a minimal power coefficient effects. This permits each shunt to be used over a wide range of currents with stable resistance characteristics.

The shunt resistance is designed to minimize interaction with the detector instrumentation. The 100 Amp shunt resistance is 8 milliohms, with shunt resistance increasing to 80 ohms for the 10 mA shunt. Additionally, the 1mA shunt includes an internal battery operated buffer amplifier. It drives the output voltage so the 800 ohm shunt resistance has minimal interaction with the measurement device.

Reports of calibration
The A40B series of precision current shunts come standard with a report of traceable calibration including data. 17025A Accredited reports of calibration are available as an optional service.

Maximum AC-DC Difference

Shunt Nominal Current:	Maximum AC-DC Difference (± ppm)1,2
	1 kHz	100 kHz
1 mA3	53	150
10 mA	20	40
20 mA	18	30
50 mA	13	16
100 mA	14	27
200 mA	17	28
500 mA	17	21
1 A	17	23
2 A	17	44
5 A	23	69
10 A	28	98
20 A	37	150
50 A	47	180
100 A	60	300
1 Specifications indicate the maximum flatness deviation from dc, and include both measured AC-DC difference and the uncertainty of measurement. They are stated at k=2, approximately 95 % confidence. 2 Includes 1-year stability of the AC-DC difference. 3 Specifications for the 1 mA current shunt are for TCal ± 1 °C.

General Specifications
Dimensions (maximum)	Shunt Value:  1 mA to 2 A Height:  70 mm (2.75 in) Width:  70 mm (2.75 in) Overall Length1:   124 mm (4.9 in) Shunt Value:  5 A to 20 A Height:  130 mm (5 in) Width:  130 mm (5 in) Overall Length1:   210 mm (8.25 in)) Shunt Value:  50 A and 100 A Height:  200 mm (7.9 in) Width:  200 mm (7.9 in) Overall Length1:   343 mm (13.5 in))  1 Includes input and output connectors; subject to change by component vendor.
Physical/mechanical parameters	Shunt Value:  1 mA to 20 A Weight:  0.7 kg (1.6 lb) Input Connector:  Type-N (female) Output Connector:  Type-N (female) Shunt Value:  50 A and 100 A Weight:  3.4 kg (7.5 lb) Input Connector:  Type-LC (female) Output Connector:  Type-N (female)
Operating environment	Temperature:  13 °C to 33 °C Calibration temperature (TCal) range:   18 °C to 28 °C Humidity range for best specification 1,2:   ≤ 50 % RH Altitude:  0 m to 3,000 m   1 Resistance stability is affected by humidity, but changes are reversible. 2 If the shunts are calibrated outside this RH, stability specifications will be met as long as the shunts are stored and used at the same relative humidity ± 10 % RH.
Storage and transit environments (for models other than the 1 mA current shunt)	Temperature to avoid damage:   -20 °C to 140 °C Temperature and humidity to maintain performance1:   5 °C to 45 °C; 15 % to 80 % RH Non-operating altitude:   0 m to 12,000 m   1 Storage at extremes of temperature or humidity will cause a temporary change of shunt resistance by up to ± 20 ppm. When subsequently stored or used within the limits of the operating environment, the shunts will recover to their original resistance value within 30 days.

Additional 1 mA current shunt specifications
Output resistance	8 mΩ
Maximum safe output current	11 mA (e.g., 1 V output into 90 Ω)
Maximum capacitive load	800 pF
Output voltage regulation	15 ppm/100 pF
Maximum output dc v offset	± 100 μV (typical ± 25 μV)
Typical error @ 1 MHz	< 2 %

Battery specifications
Battery size	AAA (44.5 mm x 10.5 mm)
Battery technology	Nickel-Metal Hydride (NiMH)
Number of batteries required	8 (in 2 groups of 4)
Nominal battery voltage	1.2 V (4.8 V per group of 4)
Typical battery capacity	800 mAh
Storage and transit environment to preserve the batteries	Less than 90 days:  -20 °C to 40 °C Less than one year:  -20 °C to 30 °C Charging time (from fully discharged):  100 minutes
Maximum operating time between charges	Maximum output load (11 mA):   18 hours High impedance load:  24 hours Recommended cooling period:  100 minutes  To prevent loss of battery capacity recharge at least twice per year.