Design Types Of Protection On The Cfu; Explosion Protection - Siemens Simatic CFU Commissioning Manual

Compact Field Unit in the enclosure for use in a hazardous area
11.3 Configuration with SIMATIC CFU PA bundle with aluminum enclosure
11.3.1.2

Design types of protection on the CFU

The types of protection include design and electrical measures relating to the equipment to
achieve explosion protection in the hazardous areas. The following types of protection are
used in the CFU:
Table 11-1 Types of protection
Type of protection Meaning
Intrinsic safety i All voltages, currents, inductance and capacitance oc‐
curring are limited by electrical measures (intrinsically
safe) - sparks or thermal effects capable of causing ig‐
nition cannot occur. The spur line connections of the
CFU fieldbus cables have an intrinsically safe design [ic].
NOTICE
The following applies when the CFU is used in hazard‐
ous areas: The spur line connections of the freely con‐
figurable channels may only be changed in a DE-ENER‐
GIZED state.
Increased-safety The enclosure and the main line terminals of the CFU
enclosure e feature the increased safety Ex e type of protection. This
type of protection is an additional measure to prevent
high temperatures, sparks and arcing from forming with
a higher degree of certainty.
Protection by en‐ The CFU is installed in the safer aluminum enclosure,
closure tc which ensures better protection against explosive dust
environments.
This type of protection is an encapsulation to prevent the
CFU from igniting conductive or non-conductive dust.
11.3.1.3

Explosion protection

Enclosure configuration
The CFU enclosure is a simple electrical equipment according to EN 60079-14 and EN 50020.
● Intrinsically safe circuits may be connected in explosion-prone areas.
● If EN 60079-14 is complied with, non-intrinsically safe current circuits may also be
connected to the SIMATIC CFU PA bundle with aluminum housing.
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Representation
Commissioning Manual, 07/2018, A5E39252870-AC
SIMATIC CFU