Low Voltage Switch Gear
Appendix
83
European Standards
■
IEC 947, EN 60947
European Standards for Low-Voltage Switchgear
For Europe and most other industrial countries of the world, the new
IEC 947 and EN 60 947 specifications for low-voltage switchgear
have unified the regulations which previously varied from nation to
nation.
This required the introduction of new terms, and new test methods
and utilization categories. The new specifications are aimed
primarily at manufacturers. However, the user also will come across
new technical terms and data in the manufacturers’ catalogues
and on the devices themselves which are important for the selection
and application of the devices. The present paper deals with the cur-
rently published specifications. Further specifications and
supplements are in preparation.
Since 1993, all low-voltage switchgear purchased in Europe had to
satisfy the EN 60 947 European Standard. Installations in existence
prior to 1993 are not affected by the standard and need not to be
refitted with new devices. Devices constructed and tested to the IEC
standards and EN standards can be used worldwide, with the excep-
tion of the USA and Canada. In these countries UL and CSA specifi-
cations continue to apply. Switchgear which conforms to IEC 947
and EN 60 947 and which has, in addition, UL- and CSA approvals,
in the meantime has entered the market. Such ‘world market’ devices
offer the advantage that they can be used throughout the world,
including the USA and Canada.
Conditions for compliance with
Type "1" coordination
(Extract from IEC 947-4-1)
- The contactor or the starter must not endanger
personnel or equipment in the event of a short
circuit
- The contactor or the starter does not need to be
suitable for continued operation without repair and
replacement of parts
- Damage to the contactor and the overload relay is
permissible
Conditions for compliance with
Type "2" coordination
(Extract from IEC 947-4-1)
- The contactor or the starter must not endanger
personnel or equipment in the event of a short
circuit
- The contactor or the starter must be suitable for
further use
- No damage may occur to the overload relay or
other parts, with the exception of welding of the
contactor or starter contacts, provided they can
be separated easily without any significant
deformation (e.g. using a screwdriver)
Rated conditional
short-circuit current l
q
- The rated conditional short-circuit
current l
q
indicates the max. short-
circuit breaking capacity of the starter
Rated operation current l
e
- The rated operational current l
e
for
the starter is the current when the
starter is in the On position
Rated uninterrupted current l
u
(to IEC 947-1)
- The rated uninterrupted current l
u
of
a unit is a current, specified by the
manufacturer, which the unit can
carry without interruption
IEC 947
IEC 947-1
General rules
IEC 947-2
Circuit-breakers
IEC 947-3
Switches, disconnectors, switch-disconnectors and fuse-combination units
IEC 947-4-1
Connectors and motor-starters
IEC 947-5-1
Control circuit devices and switching elements
IEC 947-6-1
Multiple function equipment, Automatic transfer switching equipment
IEC 947-6-2
Multiple function equipment, Control and protective switching devices (or equipment)
(CPS)
IEC 947-7-1
Ancillary equipment
