User Documentation

2 Safety | Intended use
6 1484600000/07/11.2020u-remote IP20 modules for functional safety manual
2.2 Intended use
The products of the u-remote series are intended for use in
industrial automation. A u-remote station with bus coupler
and connected modules is intended for the decentralised
control of systems or sub-systems. All modules of a station
are integrated into a eldbus structure and connected to the
superordinate control unit via the eldbus coupler.
The u-remote safe I/O modules (UR20-
*
FS
*
) as well as the
safe power-feed modules (PF-O-xDI-SIL) are intended for
connecting equipment providing functional safety. Therefore
safe I/O modules must be operated via a safety control.
The u-remote products conform to protection class IP20 (in
accordance with DIN EN 60529), they can be used in poten-
tially explosive atmospheres rated as Zone 2 (as per Directive
2014/34/EU).
The observance of the supplied documentation is part of the
intended use. The products described in this manual may
only be used for the intended applications and only in con-
nection with certied third-party devices or components.
2.3 Use in a potentially explosive atmosphere
If u-remote products are used in potentially explosive atmos-
pheres, the following notes are also applicable:
– Staff involved in assembly, installation and operation must
be qualified to perform safe work on electrical systems
protected against potentially explosive atmospheres.
– For applications in potentially explosive atmospheres, the
requirements according to IEC60079-15 must be
observed.
– The housing enclosing must be ATEX/IECEx certified
meeting the requirements of protection class IP54, acces-
sible only by use of a tool.
– The housing enclosing must meet the requirements of
explosion protection type Exn or Exe.
– Sensors and actuators that are located in Zone 2 or in a
safe zone can be connected to the u-remote station.
– Devices are for use in an area of not more than pollution
degree 2 in accordance with EN60664-1.
– Provision shall be made to prevent the rated voltage from
being exceeded by transient disturbances of more than
140 % of the rated voltage.
– When the temperature under rated conditions exceeds
70 °C at the conductor or conduit entry point, or 80 °C at
the contact, the temperature specification of the selected
cable shall be in compliance with the actual measured
temperature values.
– A visual inspection of the u-remote station is to be per-
formed once per year.
2.4 Notes on functional safety
Safety Integrity Level (SIL)
The safety requirements necessary for the safety functions
of an application are determined in a risk analysis. Here, the
probability of the safety functions failing is important. In an
operating mode with a high rate of demand or continuous
demand, the probability of dangerous failure per hour (PFH)
must be taken into consideration, whereas in an operating
mode with a lower rate of demand, the probability of danger-
ous failure on demand (PFD) must be taken into consider-
ation. According to IEC61508 and IEC62061, the safety
requirements are graded by the failure limit values as follows:
Safety requirements by failure limit values
PFD PFH
SIL3 < 10
-3
< 10
-7
SIL2 ≥ 10
-3
to < 10
-2
≥ 10
-7
to < 10
-6
SIL1 ≥ 10
-2
to < 10
-1
≥ 10
-6
to < 10
-5
Performance level (PL)
According to ENISO13849-1, the degree to which a safety
function contributes to risk minimisation is dened as the
performance level. A distinction is made between the ve
levels PLa to PLe with an increasing contribution to risk min-
imisation.
Safety categories
Safety categories according to ENISO13849-1 describe a
minimum level of applicable safety and to what extent moni-
toring is required.
Category B: The safety-related components of machine
controls and/or their safety equipment as well as their
components must be designed, selected, assembled and
combined to the state of the art such they can withstand the
expected conditions.
Category 1: The requirements of Category B must be met.
Use of proven safety-related components.
Category 2: The requirements of Category B must be met
with the use of proven safety principles. The safety functions
must be veried by the machine controls at suitable intervals
(depending on the application and the type of machine).
Category 3: The requirements of Category B must be met
with the use of proven safety principles. Controls must be de-
signed so that a single failure in the control system does not
lead to a loss of safety function(s), and whenever reasonably
practicable, the single failure shall be detected with suitable
means which meet the state of the art.
Category 4: The requirements of Category B must be met
along with the use of proven safety principles. Controls must