8 ISD Safety Concept
8.1 Applied Standards and Compliance
Use of the STO function requires that all provisions for
safety, including relevant laws, regulations, and guidelines,
are satisfied.
The integrated STO function complies with the following
standards:
•
EN 60204-1: 2006 Stop Category 0 – uncontrolled
stop
•
IEC/EN 61508: 2010 SIL 2
•
IEC/EN 61800-5-2: 2007 SIL 2
•
IEC/EN 62061: 2005 SIL CL2
•
EN ISO 13849-1: 2008 Category 3 PL d
The ISD 510 servo system has been tested for higher EMC
immunity as described in IEC/EN 61326-3-1.
8.2 Abbreviations and Conventions
Abbreviation Reference
Description
Cat.
EN ISO
13849-1
Category, level B, 1–4
DC
–
Diagnostic coverage
FIT
–
Failure in time
Failure rate: 1E-9/hour
H
EN IEC 61508 Hardware fault tolerance
H = n means that n + 1 faults may
lead to a loss of the safety
function.
MTTFd
EN ISO
13849-1
Mean time to failure – dangerous
Unit: years
PFH
EN IEC 61508 Probability of dangerous failures
per hour
Take this value into account if the
safety device is operated in high
demand mode or in continuous
operating mode, where the
frequency of demands for
operation made on a safety-related
system occurs more than once per
year.
PFD
EN IEC 61508 Average probability of failure on
demand.
This value is used for low demand
operation.
PL
EN ISO
13849-1
Performance level
A discrete level used to specify the
capability of safety-related parts of
a system to perform safety-
oriented functions under
foreseeable conditions. Levels: a–e.
Abbreviation Reference
Description
SFF
EN IEC 61508 Safe Failure Fraction [%]
Proportion of safe failures and
detected dangerous failures of a
safety function or a subsystem as a
percentage of all possible failures.
SIL
EN IEC 61508
EN IEC 62061
Safety Integrity Level
STO
EN IEC
61800-5-2
Safe Torque Off
SS1
EN IEC
61800-5-2
Safe stop 1
SRECS
EN IEC 62061 Safety-related electrical control
system
SRP/CS
EN ISO
13849-1
Safety-related parts of control
systems
PDS/SR
EN IEC
61800-5-2
Power drive system (safety-related)
Table 8.1 Abbreviations and Conventions
8.3 Qualified Personnel for Working with
the STO Function
The STO function may only be installed, programmed,
commissioned, maintained, and decommissioned by
qualified personnel. Qualified personnel for the STO
function are qualified electrical engineers, or persons who
have received training from qualified electrical engineers
and are suitably experienced to operate devices, systems,
plant, and machinery in accordance with the general
standards and guidelines for safety technology.
Furthermore they must:
•
Be familiar with the basic regulations concerning
health and safety/accident prevention.
•
Have read and understood the safety guidelines
given in this manual.
•
Have a good knowledge of the generic and
specialist standards applicable to the specific
application.
Users of power drive systems (safety-related) (PDS(SR)) are
responsible for:
•
Hazard and risk analysis of the application.
•
Identifying safety functions required and
allocating SIL or PLr to each of the functions,
other subsystems, and the validity of signals and
commands from them.
•
Designing appropriate safety-related control
systems (hardware, software, parameterization,
and so on).
ISD Safety Concept
VLT
®
Integrated Servo Drive ISD
®
510 System
66
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MG75K102
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