How To Choose A DC Shunt
A shunt is the simplest instrument in the panel and the easiest to order wrongly. Two numbers have to match, not one.
Why Not A Current Transformer
A current transformer works by electromagnetic induction and needs a changing current. On DC there is nothing to induce, so a calibrated resistance is used instead and the voltage across it is measured.
Match Both Numbers
A shunt is specified as rated current and rated voltage drop, for example 500 A / 50 mV. The instrument is scaled for a specific drop, so ordering 500 A / 75 mV for a 50 mV meter gives a reading that is wrong by half as much again. Standard drops in this range are 50, 60, 75, 100, 150, 200 and 300 mV.
Accuracy And Temperature
Accuracy class runs 0.5 to 0.2 from 1 A to 4000 A, over -40 °C to +60 °C. The blade is a precision alloy chosen so its resistance barely moves with temperature, which is what keeps the reading honest as the shunt heats up.
Heat
A shunt dissipates I²R and must be able to lose that heat. The published limits are a temperature rise not exceeding 80 °C for rated currents below 50 A and 120 °C above it. Leave free air around large shunts and do not bury them behind a busbar.
Mechanical And Overload
The range withstands 70 m/s² acceleration and six hours of transport vibration at 80 to 120 impacts per minute, and 120 % of rated current for two hours. Installation follows IEC 61010-1:1990.
Footprint
The European DIN 43703 pattern and the US base mounted pattern are different footprints and both are supplied. Say which market the panel is built for.
Products Referenced In This Guide
DC Split Core Current Transformer
Type DC split core current sensor
Frames SCT010TS-D, SCT024TS-D
Meter Current Transducer
Models 1856B05, 1876B05
System Three phase, and three phase four wire (1876B05)
Still Not Sure Which Part To Specify
Describe the circuit and the instrument. An engineer will name the frame.