Copper Shunt

A copper shunt is a calibrated low-resistance element connected in series with the circuit being measured. Current flowing through the shunt produces a small, precisely proportional voltage drop across its terminals — typically in the millivolt range — which an external meter or controller reads and converts to a current value using Ohm's law. The shunt itself carries the full load current while the voltage sense circuit draws negligible current, making it accurate across a wide dynamic range without loading the circuit under test.

The resistance element material determines how stable the shunt reading is over temperature. Pure copper has very low resistance but a high temperature coefficient — its resistance changes significantly with heating, introducing measurement error under varying load. Manganese copper alloy (manganin) has a near-zero temperature coefficient, keeping resistance stable across a wide temperature range and making it the standard choice for precision measurement shunts. For bypass and connection shunts where measurement accuracy is not the requirement, high-purity Cu-ETP is used to minimise voltage drop and power loss in the circuit.

Our shunts cover current ratings from a few amperes to several thousand amperes. Standard resistance values follow the 75mV and 60mV drop convention at rated current — the most common instrument input ranges — but custom resistance values can be produced to match any measurement system. The physical size, cross-section, and element length are calculated from the resistance and current rating combination. State the rated current, required voltage drop at full scale, and accuracy class when enquiring.

A rigid shunt transmits mechanical stress directly to its terminals and resistance element when the buswork moves due to thermal expansion, vibration, or installation misalignment. Over time this causes terminal joint fatigue, resistance drift, and eventual failure. A flexible shunt — with a braided or laminated copper body — absorbs movement and vibration at the connection points, keeping the resistance element mechanically stable and the terminal joints unstressed. For any installation subject to vibration, thermal cycling, or where precise buswork alignment cannot be guaranteed, a flexible shunt is the more reliable engineering choice.

Copper shunts are used in battery management systems and EV charging infrastructure for pack-level current monitoring, DC power supplies and rectifiers, industrial motor drives and inverters, welding equipment, electroplating lines requiring precise current control, energy meters and power analysers, and switchgear protection systems. Anywhere a direct, accurate, low-insertion-loss current measurement is needed in a DC or low-frequency AC circuit, a shunt is the straightforward solution.

Please specify: rated current, voltage drop at full scale (e.g. 75mV or 60mV), resistance value if known, accuracy class, terminal type and hole configuration, body type (braided or laminated), operating temperature range, and any surface finish or insulation requirement. For replacement shunts, a drawing or sample of the existing unit is the fastest way to confirm a direct replacement. Custom designs are welcome and samples can be produced before volume orders are confirmed.