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Abbrev. Ref.
Description
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 Off
SS1
EN 61800
-5-2
Safe Stop 1
Table 4.27 Abbreviations Related to Functional Safety
The PFDavg value (Probability of Failure on Demand)
Failure probability in the event of a request of the safety
function.
4.9.1.1 Terminal 37 Safe Stop Function
The frequency converter 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. This 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 as an emergency stop for the frequency converter.
In the normal operating mode when safe stop 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 fulfilled.
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 this manual
•
Have a good knowledge of the generic and safety
standards applicable to the specific application
User is defined as: integrator, operator, service technician,
maintenance technician.
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 startup
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
•
Qualified and skilled personnel are required for
installation and commissioning of safety
engineering systems
•
The unit must be installed in an IP54 cabinet or
in an equivalent environment. In special
applications a higher IP degree is required
•
The cable between terminal 37 and the external
safety device must be short circuit protected
according to ISO 13849-2 table D.4
•
When external forces influence the motor axis (for
example, suspended loads), to eliminate potential
hazards additional measures are required (for
example, a safety holding brake)
Safe Stop Installation and Set-Up
WARNING
SAFE STOP FUNCTION!
The safe stop function does NOT isolate mains voltage to
the frequency converter or auxiliary circuits. Perform work
on electrical parts of the frequency converter or the motor
only after isolating the mains voltage supply and waiting
the length of time specified under Safety in this manual.
Failure to isolate the mains voltage supply from the unit
and waiting the time specified could result in death or
serious injury.
•
It is not recommended to stop the frequency
converter by using the Safe Torque Off function.
If a running frequency converter is stopped by
using the function, the unit trips and stops by
coasting. If unacceptable or dangerous, use
another stopping mode to stop the frequency
converter and machinery, before using this
function. Depending on the application a
mechanical brake can be required.
•
For synchronous and permanent magnet motor
frequency converters, in a multiple IGBT power
semiconductor failure: In spite of the activation of
Application Examples
VLT
®
Decentral Drive FCD 302
68
MG04H102 - VLT
®
is a registered Danfoss trademark
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