
Functions
5.12 Safety-related applications
Frequency inverter
Operating Instructions, 08.10. 2008, t.b.d.
197
Permissible control modes for using fail-safe functions
When the prerequisites mentioned above are fulfilled, the fail-safe functions can be used for
both V/f and vector control.
Restrictions regarding SLS and SS1
CAUTION
Safety functions SS1 and SLS must not be used when the motor can still be accelerated by
the mechanical elements of the connected machine component once the frequency
converter has been shut down.
Whether or not a mechanical brake is installed is irrelevant.
Examples:
1.
With lifting gear, a vertical load can accelerate the motor as soon as the frequency
converter is shut down. In this case, safety functions SS1 and SLS are not permitted.
2.
A horizontal conveyor is always brought to a standstill due to friction as soon as the
frequency converter is shut down. In this case, safety functions SS1 and SLS can be
used without restriction.
Examples of how the safety functions can be applied
Description of problem
Suitable
safety function
Solution
When the EMERGENCY STOP button is
pressed, a stationary motor must not start
unintentionally.
STO
Control the frequency converter via
terminals by means of an EMERGENCY
STOP button.
A central EMERGENCY STOP button is
designed to prevent more than one drive
from starting unintentionally.
STO
Evaluate the EMERGENCY STOP
button in a central controller; control the
frequency converter via PROFIsafe.
A short-circuit and cable break occurring
when the motor holding brake is activated
are to be signaled.
SBC
Connect the motor holding brake to the
optional "Safe Brake Module" of the
frequency converter.
Having opened a protective door, the
machine operator must enter the
hazardous zone around a machine and
run a conveyor belt at low speed.
SLS
Control the frequency converter via
terminals by means of a button for
moving the conveyor belt.
When a protective door is opened, the
motor must be stationary.
SS1
Activate the SS1 function in the
frequency converter and enable the
protective door as soon as the frequency
converter returns "STO".