Definition :

The Hay's bridge is used to calculate the circuit's self-inductance. The bridge is a more advanced version of Maxwell's bridge. The Maxwell's bridge can only be used to calculate the medium quality factor. As a result, the Hays bridge is applied in the circuit to measure the high-quality factor.

The capacitor is linked in series with the resistance in Hay's bridge and the voltage drop across the capacitance and resistance is changed. The capacitance is linked in parallel with the resistance in a Maxwell bridge. As a result, the magnitude of the voltage passing through the resistance and capacitor is the same.

Advantages of Hay’s Bridge:

· The Hays bridges provide us with a simplified expression for unknown inductances and are ideal for coils with quality factors higher than 10 ohms.

· It provides a straight forward calculation for the quality factor.

· The Hay's bridge determines the Q factor by using small value resistance.

Disadvantages of Hay’s Bridge

· It is not suited for measuring coils with a quality factor less than 10 ohms.

Hay’s Bridge Theory:

Keypoint:

· L1– unknown inductance having a resistance

· R1,R2,R3 – known non-inductive resistance.

· C1 – standard capacitor

• The equation of the unknown inductance and capacitance consists frequency term. Thus, for finding the value of unknown inductance the frequency of the supply must be known.

• The frequency term is included in the equation of the unknown inductance and capacitance. As a result, in order to determine the value of an unknown inductance, the frequency of the supply must be known.

• For the high-quality factor, the frequency does not play an important role: