A 'Kelvin' configuration resistor features four leads or terminations. These four terminal resistors enable current to be applied through two opposite leads and a sensing voltage to be measured across the other two leads.
 
The Kelvin configuration effectively eliminates the resistance and temperature coefficient of the leads. The Kelvin connection can also simplify board design by incorporating all terminals for the sensing circuit into one part. A Kelvin connection is essential for accurate current sensing and simplified board design.

 
As the world becomes more and more technology driven, the uses for current sensing resistors will continue to increase. The need for even lower resistance value ranges is already becoming evident. The need for current sense resistors to handle more power is also an increasing demand. The industry wide trend is leaning toward smaller and smaller products, so look out for an increasing number of new resistors to fill these requirements.
 
Current measurement using a shunt resistor and voltmeter is particularly well-suited for applications involving particularly large magnitudes of current. In such applications, the shunt resistor's resistance will be in the order of milli-ohms or micro-ohms, so that only a modest amount of voltage will be dropped at full current. The resistance of some shunts can be so low that it is comparable to wire connection resistance.
 
Measuring the voltage drop across a shunt with such low values must be done in a way as to avoid detecting voltage dropped across the current carrying wire connections. Shunts are usually equipped with four connection terminals. Using a shunt this way ensures the voltmeter only measures the voltage dropped by the shunt resistance itself, without any stray voltage drops or resistance originating from wire or connection.