Class of accuracy in electrical measurements and voltmeters have a high but not infinite internal impedance. Thus the measured parameters are somewhat altered during the measurements. Let E be the EMF of the source R be the resistance of the load and r be the resistance of the ammeter. The current through the load is I When the ammeter is connected in series with the load the current I is The difference introduced by the measuring device is then, The ratio of the difference to the actual value is Class of accuracy in electrical measurements In electrical engineering class of accuracy is a figure which represents
Coal Measures Group the: In South Wales, the larger part of what had been the Upper Coal Measures now forms the Pennant Sandstone Formation in the overlying Warwickshire Group. The South Wales Coal Measures Group is preceded (underlain) by the Marros Group. Coal Measures Group The Coal Measures Group is a lithostratigraphical term coined to refer to the coal-bearing succession of rock strata which occur in the United Kingdom within the Westphalian Stage of the Carboniferous Period. Other than in Northern Ireland the term is now obsolete in formal use and is replaced by the Pennine Coal Measures Group, Scottish Coal Measures Group