WARNING
After installation of Safe Torque O (STO), a commis-
sioning test as specied in section Safe Torque O
Commissioning Test in the Design Guide must be
performed. A passed commissioning test is mandatory
after rst installation and after each change to the safety
installation.
Safe Torque O Technical Data
The following values are associated to the dierent types
of safety levels:
Reaction time for T37
•
Maximum reaction time: 10 ms
Reaction time = delay between de-energizing the STO
input and switching o the frequency converter output
bridge.
Data for EN ISO 13849-1
•
Performance Level "d"
•
MTTF
d
(Mean Time To Dangerous Failure): 24816
years
•
DC (Diagnostic Coverage): 99%
•
Category 3
•
Lifetime 20 years
Data for EN IEC 62061, EN IEC 61508, EN IEC 61800-5-2
•
SIL 2 Capability, SILCL 2
•
PFH (Probability of Dangerous failure per
Hour)=7e-10FIT=7e-19/h
•
SFF (Safe Failure Fraction) >99%
•
HFT (Hardware Fault Tolerance)=0 (1001
architecture)
•
Lifetime 20 years
Data for EN IEC 61508 low demand
•
PFDavg for one-year proof test: 3, 07E-14
•
PFDavg for three year proof tests: 9, 20E-14
•
PFDavg for
ve year proof tests: 1, 53E-13
No maintenance of the STO functionality is needed.
Take the necessary security measures, e.g. installation in a
closed cabinet that is only accessible for skilled personnel.
SISTEMA Data
Functional safety data is available via a data library for use
with the SISTEMA calculation tool from the IFA (Institute
for Occupational Safety and Health of the German Social
Accident Insurance), and data for manual calculation. The
library is permanently completed and extended.
Abbrev. Ref. Description
Cat. EN 954-1 Category, level “B, 1-4”
FIT Failure In Time: 1E-9 hours
HFT IEC 61508 Hardware Fault Tolerance: HFT = n
means, that n+1 faults could cause a
loss of the safety function
MTTFd EN ISO
13849-1
Mean Time To Failure - dangerous. Unit:
years
PFH IEC 61508 Probability of Dangerous Failures per
Hour. Consider the PFH value when the
safety device is operated in high
demand (more often than once per
year); or operated in continuous mode,
where the frequency of demands for
operation made on a safety-related
system is greater than one per year.
PL EN ISO
13849-1
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.
SFF IEC 61508 Safe Failure Fraction [%]; Percentage part
of safe failures and dangerous detected
failures of a safety function or a
subsystem related to all failures.
SIL IEC 61508 Safety Integrity Level
STO EN
61800-5-2
Safe Torque O
SS1 EN 61800
-5-2
Safe Torque O 1
Table 2.1 Abbreviations Related to Functional Safety
The PFD
avg
value (Probability of Failure on Demand)
Failure probability in the event of a request of the safety
function.
2.2.1 Terminal 37 Safe Torque O Function
The frequency converter is available with Safe Torque O
functionality via control terminal 37. Safe Torque O
disables the control voltage of the power semiconductors
of the frequency converter output stage. This in turn
prevents generating the voltage required to rotate the
motor. When the Safe Torque O (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 Torque O function can be used as an emergency
stop for the frequency converter. In normal operating
mode when Safe Torque O is not required, use the
regular stop function instead. When automatic restart is
used, ensure the requirements of ISO 12100-2 paragraph
5.3.2.5 are fullled.
Safety Instructions and Gen...
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