Rockwell Automation Low-Voltage Switchgear and Controlgear - Manual (Page 29)

2 Switching tasks and selecting the appropriate switchgear
The selection and use of electrical equipment for switchgear assemblies and machine control
units are regulated under the respective national legislation. Within the European Union (EU)
the regulations are based on the CENELEC standards (EN standards) which are largely
identical with the IEC standards. The IEC standards also form the basis of the applicable
regulations in a large number of other countries. In North America, the standards of UL or CSA
as well as the directives of NEMA, NEC etc. have to be applied. All these standards and
regulations have as their common goal to guarantee the safety of electrical installations.
2.1 Electrical equipment complying with standards and matching
the application requirements
The standards IEC 60439-1 (Low-voltage switchgear and controlgear assemblies ) and
IEC 60204-1 (Electrical equipment of machines) require among other things that the electrical
equipment must correspond to the valid applicable standards. This means that low-voltage
switchgear must be built and tested in compliance with the requirements of IEC 60947. Fur-
thermore, the external design of the electrical equipment, its rated voltages, rated currents, life
span, the making and breaking capacity, the short-circuit withstand capacity etc. must be
suitable for the respective application. If necessary current-limiting protective devices must be
used for protecting the electrical equipment. The coordination of electrical equipment, for
example of motor starters to short-circuit protection equipment must comply with the applicable
norms. When selecting electrical equipment the rated impulse withstand voltages and the
generated switching overvoltages have to be considered.
According to these standards, all devices that are available on the market must comply with the
applicable standards. For the EU and the EEA, this compliance is confirmed by a declaration of
conformity by the manufacturer and the CE-sign. The same requirements apply to Switzerland,
with the exception that the CE-sign is not compulsory (but is permitted). Other countries have
their own licensing procedures and signs of conformity. So requires China the CCC-mark and
Australia and New Zealand have introduced the C-tick-mark for EMC compliance of electronic
products.
Fig. 2.1-1
CE-sign for the EU market (left), CCC-sign for China (center) and C-tick-mark for Australia and New
Zealand
For special applications such as for example shipping, railroads or applications in hazardous
environments where a risk of explosion exists, specific regulations apply in many cases that
usually contain additional requirements beyond the basic IEC standards.
The standards to which the devices have been built and tested are listed in the catalogs. For
low-voltage switchgear (contactors, motor starters, circuit breakers, load switches etc.) for the
markets outside North America, these standards are basically the various parts of the
IEC 60947.
2.2 Basic switching tasks and criteria for device selection
Load circuits include functional components in accordance with Fig. 2.2-1 , whereby several
functions can be combined in a single device.
LVSAM-WP001A-EN-P - April 2009 2-1