Calibration is the process of configuring an instrument to provide a result for a sample within an acceptable range. Eliminating or minimizing factors that cause inaccurate measurements is a fundamental aspect of instrumentation design.
This method can be discussed in:
DC AND AC VOLTMETER
DC AND AMMETER
OHMMETER
POTENTIOMETER
The test voltmeter (V) reading is compared to the voltage reading obtained using standard instrument (M).
DC ammeter can be calibrated using a standard resistor R
and a standard voltmeter
To calibrate an ammeter, you need a 1 ohm reference shunt in series with the meter and measure the voltage drop across the shunt with a Potentiometer.
The test ammeter (A) reading is compared to the calculated Ohm’s Law current where the voltage reading obtained across the known standard resistor R, using the standard voltmeter(M).
The ohmmeter designed around the d’Arsonval meter movement is considered to be an instrument of moderate accuracy.
The accuracy of the instrument can be checked by measuring different values of standard resistance and noting the reading obtained.
A simple 0 Ω calibration is done by connecting its probe together and adjusting the 0 Ω adjustment knob so that its pointer points the 0 Ω mark.
DC moving coil-type movement in which an electromagnetic core is suspended between the poles of a permanent magnet
Called as Permanent-Magnet Moving Coil (PMMC)
The deflection of the pointer is directly proportional to the amount of current passing trough the coil