Danfoss VLT AutomationDrive Design Manual page 53

Introduction to FC 300
Abbreviations related to Functional Safety
Abbrev. Ref.
Cat. EN
954-1
FIT
3 3
HFT IEC
61508
MTTFd EN
ISO
13849
-1
PFH IEC
61508
PL EN
ISO
13849
-1
SFF IEC
61508
SIL IEC
61508
STO EN
61800
-5-2
SS1 EN
61800
-5-2
The PFDavg value (Probability of Failure on Demand)
Failure probability in the event of a request of the safety
function.
3.12.1 Terminal 37 Safe Stop Function
The FC 302 and FC 301 (optional for A1 enclosure) is
available with safe stop functionality via control terminal
37. Safe stop disables the control voltage of the power
semiconductors of the frequency converter output stage
which in turn prevents generating the voltage required to
rotate the motor. When the Safe Stop (T37) is activated,
the frequency converter issues an alarm, trips the unit, and
coasts the motor to a stop. Manual restart is required. The
safe stop function can be used for stopping the frequency
converter in emergency stop situations. In the normal
operating mode when safe stop is not required, use the
frequency converter's regular stop function instead. When
automatic restart is used – the requirements according to
ISO 12100-2 paragraph 5.3.2.5 must be fulfilled.
52
FC 300 Design Guide
Description
Category, level "B, 1-4"
Failure In Time: 1E-9 hours
Hardware Fault Tolerance: HFT = n means, that
n+1 faults could cause a loss of the safety
function
Mean Time To Failure - dangerous. Unit: years
Probability of Dangerous Failures per Hour. This
value shall be considered if the safety device is
operated in high demand (more often than
once per year) or continuous mode of
operation, where the frequency of demands for
operation made on a safety-related system is
greater than one per year
Discrete level used to specify the ability of
safety related parts of control systems to
perform a safety function under foreseeable
conditions. Levels a-e
Safe Failure Fraction [%] ; Percentage part of
safe failures and dangerous detected failures of
a safety function or a subsystem related to all
failures.
Safety Integrity Level
Safe Torque Off
Safe Stop 1
MG.33.BD.02 - VLT
Liability Conditions
It is the responsibility of the user to ensure personnel
installing and operating the Safe Stop function:
•
Read and understand the safety regulations
concerning health and safety/accident prevention
•
Understand the generic and safety guidelines
given in this description and the extended
description in the Design Guide
•
Have a good knowledge of the generic and safety
standards applicable to the specific application
User is defined as: integrator, operator, servicing,
maintenance staff.
Standards
Use of safe stop on terminal 37 requires that the user
satisfies all provisions for safety including relevant laws,
regulations and guidelines. The optional safe stop function
complies with the following standards.
EN 954-1: 1996 Category 3
IEC 60204-1: 2005 category 0 – uncontrolled stop
IEC 61508: 1998 SIL2
IEC 61800-5-2: 2007 – safe torque off (STO)
function
IEC 62061: 2005 SIL CL2
ISO 13849-1: 2006 Category 3 PL d
ISO 14118: 2000 (EN 1037) – prevention of
unexpected start up
The information and instructions of the instruction manual
are not sufficient for a proper and safe use of the safe stop
functionality. The related information and instructions of
the relevant Design Guide must be followed.
Protective Measures
•
Safety engineering systems may only be installed
and commissioned by qualified and skilled
personnel
•
The unit must be installed in an IP54 cabinet or
in an equivalent environment. In special
applications a higher IP degree may be necessary
•
The cable between terminal 37 and the external
safety device must be short circuit protected
according to ISO 13849-2 table D.4
•
If any external forces influence the motor axis
(e.g. suspended loads), additional measures (e.g.,
a safety holding brake) are required in order to
eliminate hazards
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is a registered Danfoss trademark