IEC 61554:1999 pdf download – Panel mounted equipment – Electrical measuring instruments -Dimensions for panel mounting

IEC 61554:1999 pdf download – Panel mounted equipment – Electrical measuring instruments -Dimensions for panel mounting.
It applies to the following types of instruments with protruding bezel::
— instruments with square housing;
— instruments with rectangular housing with lateral orientation:
— instruments with rectangular housing with upright orientation;
— instruments with round housing and square bezel:
— instruments with round housing and rectangular bezel.
The purpose of this standard is to establish dimensional interchangeability between instruments made by different manufacturers. To fulfil this requirement, a defined set of dimensions has been chosen. Using these dimensions, it should be easy to combrne instruments 01 different sizes on the same panel making good use of the available panel space and to produce a satisfactory layout.
2 Definitions
For the purpose of this International Standard the following definitions apply
2.1
cut-oul
the hole In the panel Into which the Instrument or group of instruments Is inserted
2.2
bezel
the front projecting surface or rim around the housing of the instrument
2.3
Instrument size
the overall maximum width and height of the bezel
3 RequIrements
3.1 General
The instrument size serves as a basis for defining the various dimensions which permit interchangeability of the instrument.
Only positive tolerances are allowed for cutout dimensions and only negative tolerances for the instrument size.
The dimensions of the housings of the instruments are not specified in this standard. The only exception to this is instruments with round housing which are covered In annex A.
Instruments that are mounted together in a common cut-out are shown as mounted without any gaps between them. The method for determining the dimensions of the common cut-out is specified below.
In the tables and drawings included In this standard, the following symbols are used:
Al bezel width;
A2 bezel height;
Li cut-out width;
L2 cut-out height.
3.2 Instrument size designation
The size designation of instruments complying with the requirements of this standard shall be as follows:
IEC 61554—Al xA2
3.3 Dimensions
In general, the dimensions shall allow easy central mounting of the instrument into the Cut-Out.
On each side, the housing of the Instrument shall have a clearance of at least 0.2 mm against the cut-out 48 mm or at least 0,5 mm for all other instrument, The maximum value of this clearance shall be such that it shall still allow the instrument to find a position where the Cut-Out ‘S not visible.
3.4 IndIvidual cut-out mounting
The nominal instrument sizes and the corresponding cut-out sizes and maximum tolerances
for the different shapes of instruments shown in figures 1 • 2 and 3 are given in table 1. The series of nominal instrument sizes and cut-out sizes can be extended according to the logical sequence of values. Values for the corresponding upper tolerances shall be in accordance with the relevant ISO tolerance range.
3.5 Common cut-out mounting
Instruments with square and rectangular housing are often mounted closely together in a group in a common Cut-out. In such instances the dimensions of the Cut-Outs depend upon the number and sizes of the Instruments and upon the overhang of the bezels of the Instruments at either end of the group
A formula is given below for calculating the overall size of the common cut-out.
When mounting a group of instruments in a row in a common cut-out, as shown in figure 4.
the overall cut-out width Lc shall be calculated as the sum of the widths Al of the individual
Instruments In the group, minus 3 mm. This formula does not apply to instruments with a width
Al less than 36 mm.