An improved lead wire compensation technique for conventional four wire resistance temperature detectors (RTDs)

A new lead wire compensation technique is presented for conventional four wire resistance temperature detectors (RTDs). Existing four wire resistance temperature detectors generally use bridge balance technique to achieve balance and unbalance bridge output is calibrated in terms of unknown temperature. Out of the four leads, two leads are connected to one arm of the bridge while the other two leads are connected to the opposite arm of the bridge, normally known as ratio arms. The presented technique totally nullifies the effect of lead resistances and any temperature variations along the lead wires will not affect the measurement accuracy.