Temperature control method for AC resistance standard

Double Helix Resistor (DHR), a kind of calculable AC/DC resistor that can be traced to quantum standard, is being developed as AC resistance standard in National Institute of Metrology (NIM). In order to improve the value stability of DHR, this paper presents a practical temperature auto-feedback control method based on four-arm electric bridge. The bridge uses one thermistor to detect temperature variation and one adjustable resistor to regulate bridge ratio. The temperature inside the specially designed resistance box can be changed and well maintained through dynamically regulating and balancing the bridge. Measurement results show that the relative stability of DHR is greatly enhanced by using the presented method.