BS 89-1:1990 pdf free.Direct acting indicatinganalogue electrical measuring instrumentsand their accessories —Specification for definitions andgeneral requirements common to all Parts.
BS 89-1 for the determination of intrinsic errors preconditioning is specified, the manufacturer shall statethe preconditioning period and the value(s) of the measured quantity(ies).The preconditioning period shallnot exceed 30 min.Instruments and accessories shall be adequately packed to ensure that, after transport to the user,under normal conditions, they comply with the requirements of this standard relating to their class index.4 Reference conditions and intrinsic errors.sThe reference values of the influence quantities shall be as given in Table I-1.
The reference value for the ambient temperature shall be selected from 20 °C, 23 °C or 27°C whichare in accordance with IEC Publication 160: Standard Atmospheric Conditions for Test Purposes.
Reference conditions different from those given in Table I-1 may be specified, but they shall then bemarked in accordance with Clause 8.Limits of intrinsic error, fiducial value.When the instrument together with its non-interchangeable accessory(ies)(if any) or accessory is under thereference condition given in ‘Table I-1 and is used between the limits of its measuring range and in accordance with the manufacturer’s instructions, the intrinsic error, expressed as a percentage of thefiducial value1), shall not exceed the limits appropriate to its accuracy class. Values stated in a table ofcorrections supplied with the instrument or accessory shall not be taken into account in determining theerrors.NOTE 1 The intrinsic error includes other errors such as those due to friction, amplifier drift, etc.
NOTE2 The accuracy classes relating to each type of instrument or accessory are given in the appropriate parts (Clause 3). Correspondence between intrinsic error and accuracy class.The maximum permissible error is related to the accuracy class such that the class index is used as thelimit of error, expressed as a percentage with positive and negative signs.NOTE For example, for a class index of 0.05, the limits of intrinsic error are ± 0.05 % of the fiducial value.BS 89-1 pdf download.