Bitzer VARIPACK FDU+12, Operating Instructions Manual

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CB-100-1 60
5.6 Safe Torque Off (STO)
As standard, the VARIPACK frequency inverters are
equipped with a certified and safety-tested shut-off
function, Safe Torque Off (STO).
• The STO function ensures that no torque-generating
energy can act any more on the compressor motor.
This will prevent an unexpected start according to
EN 60204-1 Section 5.4.
• The STO function safely deletes all pulses of the
drive. The drive is safely free of torque. This state is
monitored inside the drive.
• The STO function allows the main contactor up-
stream or downstream of the VARIPACK to be omit-
ted. Instead of being switched as before via the main
contactor, the STO, switched via the high-pressure
switch or other safety-relevant protective functions,
can shut off the compressor directly.
DANGER
The STO function is not a galvanic isolation and
may therefore not be used for maintenance or
repair work!
It is only an electronic protective function during
normal operation of the VARIPACK frequency
inverter.
Prior to performing maintenance or repair work,
the VARIPACK must be completely disconnec-
ted from the mains supply using a suitable elec-
trical disconnecting device and proper isolation
of all voltage connections must be checked!
Switch off the main switch and secure it against
being switched on again.
Wait for at least 5 minutes until all capacitors
have been discharged!
Information
The STO function is a factory built-in and tested
function.
Repairs on VARIPACK frequency inverters
equipped with STO function may only be carried
out authorized staff.
Any unauthorized attempt to repair or dismantle
the VARIPACK will void the guarantee and may
impair the STO function.
As soon as the VARIPACK frequency inverter
will detect an internal STO error, it must be elim-
inated immediately.
!
!
NOTICE
Defined switching points are no longer guaran-
teed if lines are too long or incorrectly installed.
Maximum line length to terminals X10/01,
X10/03, X10/05 and X10/06: 25 m!
Install lines only inside the switch cabinet or the
FI housing!
• For high safety requirements, two independent STO
control channels have been implemented in the
hardware. The STO circuit is designed such that
upon occurrence of an error in a channel, the second
channel ensures that no inadvertent operation of the
VARIPACK frequency inverter takes place.
• The activated STO function overrides all attemps to
start the compressor. This means that if the STO
function is switched by one or both STO control in-
puts, the compressor will not start. This is also true
if, for example, an internal software error should res-
ult in a start attempt.
Safety specifications:
According to EN ISO13849-1 and EN 61800-5-2, the
VARIPACK frequency inverters have the following
safety characteristics:
Safety level reached by the frequency inverters
①
SIL Safety integrity level SIL3
PL Performance level PLe
Underlying safety characteristics ②
PFH Probability of dangerous
failures per hour 2,3 x 10
-9
MTTF
d
Mean time to dangerous
failure 100 years
③
DC Diagnostic coverage 98.6% →
high
SFF Safe failure fraction 99% → av-
erage
T
M
Mission time 20 years
Tab. 5: VARIPACK safety characteristics according to EN
ISO12849-1 and EN 61800-5-2
①: The indicated safety levels and the respective
safety characteristics are applicable for the VARIPACK
frequency inverter if both STO inputs can be activated
independently of each other. Depending on the integra-
tion into the system, the safety level of the complete
system can be lower and must be calculated by the
system manufacturer.