Danfoss FC 102 Design Manual page 17

Introduction to VLT® HVAC D...
Abbrev. Ref. Description
Cat. EN ISO Category, level "B, 1-4"
13849-1
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 Mean Time To Failure - dangerous. Unit:
13849-1 years
PFH IEC 61508 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
PFD IEC 61508 Average probability of failure on
demand, value used for low demand
operation.
PL EN ISO Discrete level used to specify the ability
13849-1 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 Safe Torque Off
61800-5-2
SS1 EN 61800 Safe Stop 1
-5-2
Table 2.2 Abbreviations Related to Functional Safety
2.6.1 Terminal 37 Safe Torque Off Function
The FC 102 is available with Safe Torque Off functionality
via control terminal 37. Safe Torque Off 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 Torque Off (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 Off function can be used for stopping the
frequency converter in emergency stop situations. In the
normal operating mode when Safe Torque Off 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.
MG11BC02
Design Guide
Liability Conditions
It is the user's responsibility to ensure personnel installing
and operating the Safe Torque Off function:
•
•
•
Standards
Use of Safe Torque Off on terminal 37 requires that the
user satisfies all provisions for safety including relevant
laws, regulations and guidelines. The optional Safe Torque
Off function complies with the following standards.
The information and instructions of the Operating
Instructions are not sufficient for a proper and safe use of
the Safe Torque Off functionality. The related information
and instructions of the relevant Design Guide must be
followed.
Protective Measures
•
•
•
•
Danfoss A/S © Rev. 06/2014 All rights reserved.
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
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
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 to eliminate
hazards
2 2
15