PERTEMUAN 9 JEMBATAN DC&AC dan APLIKASINYA

PENDAHULUAN Sirkuit jembatan biasanya digunakan untuk mengukur nilai komponen, seperti resistansi, induktansi, kapasitansi dan parameter sirkuit lainnya Keakurasiannya sangat tinggi

Wheatstone bridge [CONTENTS]CONTENTS Photograph of the instrument Simplified schematic of the bridge circuit 

Operasi dasar Measurement errors : –Found in the limiting errors of the three known resistors –Insufficient sensitivity of the null detector –Changes in resistance of the bridge arms due to the heating effect of the current through the resistors –Thermal emfs in the bridge circuit or the galvanometer circuit (when low- value resistors are being measured) –Errors due to the resistance of leads and contacts exterior to the actual bridge circuit

Thevenin Equivalent Circuit Wheatstone bridge configuration  Thevenin resistance looking into terminals c and d  Complete Thevenin circuit, with the galvanometer connected to terminals c and d

The Thevenin, or open circuit voltage : The Thevenin resistance : The galvanometer current :

Kelvin Bridge Wheatstone bridge circuit, showing resistance R y of the lead from point m to point n Basic Kelvin double bridge circuit 

Loop Tests with The Portable Test Set Murray-loop test, used for locating a ground fault (short circuit)  Varley-loop test: (a) no.1; (b) no. 2; (c) no.3, used to locate grounds, crosses, or short circuits in multiconductor cable (b)

Guarded Wheatstone Bridge Used for high resistance measurements

General Form of The AC Bridge

Comparison Bridges Capacitance comparison bridge Equating the real terms : Equating the imaginary terms : Inductance comparison bridge

Inductance comparison bridge with extended measurement range With the switch in position 1 : With the switch in position 2 :