This recommendation defines a system of dimensions for electrical and electrically operated indicating measuring instruments of the panel type.
Note. — This system of standardization is intended to limit the number of sizes, but not to restrict future technical change. Therefore, in the future, some sizes may be deleted if it is found that they are not used in current practice. On the other hand, other sizes may be added provided that they are in accordance with this modul?r system.
In particular, the following types of instruments with protruding flanges are included:
— square indicating instruments with round housing,
— rectangular indicating instruments with round housing,
— square indicating instruments with square housing,
— rectangular indicating instruments with rectangular housing.
It also applies to rectangular indicating instruments with rectangular housing without continuous flange.
For the present, forward and backward projections of instruments are not within the scope of this recommendation.
Notes I. — The depth behind the panel is particularly important when constructing instrument r?cks and cabinets.
2. — Instruments ean be mounted in different ways: either individually on the panel using bolts or other fixing devices, the housing of the instrument fitting mto the cutout, or collectively in a common cutout (e.g. "shelf mounting").