A very low value resistor with a four-terminal connection allows the current to pass through the resistor with minimum power loss and still measure the IR drop to monitor the current. Current sensing of very large amounts of current requires a correspondingly large resistor with a suitable heat sink to draw away the heat generated. Vishay Foil technology lends itself uniquely to this application because the flat foil is bonded to a thin ceramic backing which can dissipate considerable heat to the sink below. The resistors’ very low temperature coefficient prevents any error drift as a result of self-heating due to high currents.