Calibration of ammeter using slide wire potentiomter

AIM:

To calibrate the given ammeter ( 0 – 5)A using slide wire potentiometer.

EQUIPMENTS REQUIRED:

Ammeter , Slide wire potentiometer Kit, Standard cell , Galvanometer, Standard resistance box

THEORY:

A potentiometer instrument for measuring the potential (or voltage) in a circuit taps off a fraction of a known voltage from a resistive slide wire and compares it with the unknown voltage by means of a galvanometer. The potentiometer method is the usual basis for the calibration of voltmeters, ammeters, and wattmeter’s. Since the potentiometer is a DC measurement device, the instrument to be calibrated must be of the DC or electrodynamometer type. 

PROCEDURE:

1. Connections are made as per the circuit diagram.
2. Combination of  dial resistance and slide wire is set to be standard cell voltage and putting key in standard position and standardize the potentiometer.
3. Then the key is kept at operate position.
4. The Rheostat is adjusted for different values of ammeter reading the voltage drop across the standard resistance is measured using slide wire potentiometer.
5. The current through standard resistance is found out by I = V/S , where S is the standard resistance.

OBSERVATION:

CALCULATION:

Percentage Error ( % Error) = [(Ii – Ia)/ Ia] * 100

MODEL GRAPH:

RESULT:

The given Ammeter (0-5)A is calibrated using slide wire potentiometer.