Accuracy and Standard of the M.C and M.I Instruments Accuracy It is the closeness with which an instrument reading approaches the true value of the quantity being measured. Thus accuracy of a measurement means conformity to truth. Accuracy in case of M.C Instrument: The accuracy of M.C instruments is of the order of generally 2% of full scale deflection because the torque to weight ratio is high in case of M.C instruments. These instruments are very accurate if design properly. Accuracy in case of M.I Instruments: M.I instruments are capable of giving an accuracy within limits of both precision and industrial grades. Modern well designed portable M.I instruments have a D.C error of 2% or less. The initial accuracy of high grade instruments is 0.75% for frequency between 25 to 125 Hz and 0.2% to 0.3% at 50 Hz. These instruments usually have less accurate. Standard M.C and M.I instruments are calibrated at the time of manufacture against a measurement standard. A standard is a physical ...