Cable Screened twisted pair (STP)
Impedance
120 Ω
Cable length Max. 1200 m (including drop lines)
Max. 500 m station-to-station
Table 2.8 Cable Information
2.5 Safe Stop
The frequency converter can perform the safety function
Safe
Torque Off (STO,
as defined by EN IEC 61800-5-2
1
) and
Stop Category 0 (as defined in EN 60204-1
2
).
Danfoss has named this functionality Safe Stop. Before
integration and use of Safe Stop in an installation, perform
a thorough risk analysis to determine whether the Safe
Stop functionality and safety levels are appropriate and
sufficient. Safe Stop is designed and approved suitable for
the requirements of:
- Safety Category 3 according to EN ISO 13849-1
- Performance Level "d" according to EN ISO
13849-1:2008
- SIL 2 Capability according to IEC 61508 and EN
61800-5-2
- SILCL 2 according to EN 62061
1)
Refer to EN IEC 61800-5-2 for details of Safe torque off
(STO) function.
2)
Refer to EN IEC 60204-1 for details of stop category 0
and 1.
Activation and Termination of Safe Stop
The Safe Stop (STO) function is activated by removing the
voltage at Terminal 37 of the Safe Inverter. By connecting
the Safe Inverter to external safety devices providing a safe
delay, an installation for a safe Stop Category 1 can be
obtained. The Safe Stop function can be used for
asynchronous, synchronous, and permanent magnet
motors.
WARNING
After installation of Safe Stop (STO), a commissioning test
as specified in 2.5.2
Safe Stop Commissioning Test must be
performed. A passed commissioning test is mandatory
after first installation and after each change to the safety
installation.
Safe Stop Technical Data
The following values are
associated to the different types
of safety levels:
Reaction time for T37
- Maximum reaction time: 20 ms
Reaction time = delay between de-energizing the STO
input and switching off the frequency converter output
bridge.
Data for EN ISO 13849-1
- Performance Level "d"
- MTTF
d
(Mean
Time To Dangerous Failure): 14000
years
- DC (Diagnostic Coverage): 90%
- 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)=1E-10/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: 1E-10
- PFDavg for three year proof test: 1E-10
- PFDavg for five year proof test: 1E-10
No maintenance of the STO functionality is needed.
Security measures have to be taken by the user e.g. instal-
lation 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.
2.5.1 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 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 that qualified
personnel installs and operates the safe stop function:
Installation
VLT
®
HVAC Drive Operating Instructions
MG11AI02 - VLT
®
is a registered Danfoss trademark
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