SCHERING BRIDGE
SCHERING BRIDGE Introduction A Schering Bridge is an AC bridge used to measure: Unknown capacitance Dielectric loss of a capacitor Dissipation factor (tan δ) Quality of insulating materials It is especially useful for measuring high-voltage capacitors and insulation capacitance . The bridge works on the principle of null detection , similar to other AC bridges Basic Principle The Schering Bridge consists of four arms: Unknown capacitor CxC_x with its resistance RxR_x Standard capacitor CsC_s Non-inductive resistor R3R_3 Variable resistor R4R_4 and capacitor C4C_4 An AC supply is connected across one diagonal of the bridge, and a null detector is connected across the other diagonal. At balance: Current through the detector is zero. Therefore, the impedance ratio of the two arms is equal Schering Bridge Circuit Where: CxC_x = unknown capacitance RxR_x = equivalent series loss resistance of unknown capacitor CsC_s ...