2 Engineering
2.10 STO function
DA1 Variable Frequency Drives 11/16 MN04020005Z-EN www.eaton.com 69
The STO function integrated into DA1 variable frequency drives meets the
definition of a “safe stop” as specified in IEC 61800-5-2 and of a non-
controlled stop as per Category 0 (emergency switching off) as specified in
IEC 60204-1. This means that the motor will coast when the STO function is
activated. The method used for stopping must be appropriate for the system
being driven by the motor.
The STO function is approved for use as a fail-safe method even in cases in
which the STO signal is not present and a single fault has occurred in the
drive. The drive was accordingly tested in accordance with the following
security standards:
The values provided here can only be ensured if the DA1 variable frequency
drive is installed in an environment that stays within the permissible limits:
• Ambient temperature range: -10 to +50 °C, taking into account any limits
that depend on frame size and degree of protection
• Maximum altitude for rated operation: 1000 m above sea level,
with altitude derating of 1% for every 100 m above 1000 m (up to max.
4000 m for IEC / 2000 m for UL)
• Relative humidity: < 95% (non-condensing). The DA1 variable frequency
drive must always be free of frost and moisture.
SIL
(Safety Integrity
Level)
PFH
d
(Probability of dangerous
Failures per Hour)
SFF (%)
(Safe Failure Fraction)
Lifetime
assumed
EN 61800-5-2
2 1.23E-09 1/h (0.12 % of SIL 2) 50 20 Yrs
PL
(Performance Level)
CCF (%)
(Common Cause Failure)
EN ISO 13849-1 PL d 1
SIL CL
EN 62061_x SIL CL 2
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