Introduction to BRIDGES
Maxwell's bridge:
Maxwell's Bridge circuit use to measures the unknown an inductance by comparison with a variable standard self-inductance.
The Maxwell's bridge is very useful for measurement of a wide range of inductance at power and audio frequency.
It is a real product bridge.,A Maxwell Bridge (in long form, a Maxwell-Wien bridge) is a type of Wheatstone bridge used to measure an unknown inductance (usually of low Q value) in terms of calibrated resistance and capacitance.
Any one of the four resistors in the above bridge can be the resistor of unknown value, and its value can be determined by a ratio of the other three, which are “calibrated,” or whose resistances are known to a precise degree. When the bridge is in a balanced condition (zero voltage as indicated by the null detector), the ratio works out to be this:
In a application R1 and R4 are known fixed entities, and R2 and C2 are known variable entities. R2 and C2 are adjusted until the bridge is balanced.
R3 and L3 can then be calculated based on the values of the other components:
Schering Bridge:
The Schering Bridge is basically a four-arm alternating-current (AC) bridge circuit whose measurement depends on balancing the loads on its arms.
A Schering Bridge is a bridge circuit used for measuring an unknown electrical capacitance and its dissipation factor.
The dissipation factor of a capacitor is the the ratio of its resistance to its capacitive reactance.
The dissipation factor of a capacitor is the the ratio of its resistance to its capacitive reactance.
Kelvin double bridge:
It is used to measure an unknown electrical resistance below 1 Ω.
Kelvin double bridge is a measuring instrument invented by William Thomson, 1st Baron Kelvin.
operation of it is similar to the Wheatstone bridge except for the presence of additional resistors.
It consist of two sets of ratio arms. First outer set of ratio arms are the known resisters & inner ratio arms are helps to connect the one terminal of galvanometer at appropriate point(which was the disadvantage of Kelvin first bridge).
It consist of two sets of ratio arms. First outer set of ratio arms are the known resisters & inner ratio arms are helps to connect the one terminal of galvanometer at appropriate point(which was the disadvantage of Kelvin first bridge).
These additional low value resistors and the internal configuration of the bridge are arranged to substantially reduce measurement errors introduced by voltage drops in the high current (low resistance) arm of the bridge .
Applications of Kelvin double bridge:
-This bridge is used to measurement of low resistance.
Post a Comment