Download IS/IEC 1131-2 (1992): Programmable Controllers, Part 2: Equipment

ISflEC 113%2(1992)
dielectric test voltage of table 17 in 3.10.2 for reinforced
the highest rated operattonal voltage of the unit.
4.7.1.2
insulation
corresponding
to
Class -II equipment
Class II equipment may have an internal functional bonding conductor but shall not be
provided with an earthing terminal or an earthing conductor in the supply cord.
4.7.2
Protective earthing terminal
If the PC-system is provided with a protective earthing terminal (class I equipment), the
following requirements also apply in addition to the previous general connection specifications:
1) the protective earthing terminal shall be readily accessible and so placed that the
connection of the equipment to the protective earthing conductor is maintained when
the cover or any removable part is removed;
2) products which are intended for cord connected use (such as peripherals) shall be
provided with a protective earthing terminal integral to the plug cap, or socket -(if removable cordset);
3) the protective earthing terminal shall be of the screw type and shall be made of
brass or other suitable non-corrosive material;
4) the clamping means of protective earthing terminals shall Abe adequately locked
against accidental loosening and it shall not be possible to loosen them without Ihe aid
of a tool;
5) protective
earthing terminals and -earthing contacts
connected to the neutral terminal at the PC-system.
NOTE - A terminal intended to be connected
function-of the protective earthing terminal.
to the PEN (protective
shall
earth neutral)
not
be
conductor
electrically
may fulfil the
6) the protective earthing terminal and subsequent protective equipment internal to the
PC-system shall provide 0,i R protective earthing continuity under 30 A continuous
fault conditions;
7) the protective earthing terminal shall have no other function.
4.8
Functional earthing
There are no constructional requirements such as noise immunity control, RFI protection,
etc., for functional earthing terminals (except for marking requirements
as given in
4.12.2.6).
4.9
Interconnecting
4.9.1
cables and cords
General
The followlng requirements shall apply to interconnecting cords or cables provided
manufacturer for the internal and/or external wiring of PC-system.
4.9.2
by the
Wiring internal to the PC-system (internal wiring)
1) The insulation, when provided, on all internal wiring of the equipment
for the voltage and the temperature conditions of use.
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shall be rated