F1 Fuse
S1 Switch: Start/stop
S2 Pushbutton: Reset
S3 Pushbutton: EMERGENCY OFF
S4 Pushbutton: Monitored start (safety relay)
Q1 Motor starter protector
Q11 3RW55 Failsafe soft starter
Q21 Contactor
K Safety relay
M1 Motor
P1 Indicator light
PE Protective conductor
When the EMERGENCY OFF (S3) pushbutton is pressed, the 3RW55 Failsafe soft starter performs
the "Safe Torque O" (STO) safety function. Execution of this safety function is signaled on the
display of the 3RW5 HMI High Feature with the message text "Safety-related shuto". After
EMERGENCY OFF (S3) has been reset, the safety relay (K) must also be reset with the Monitored
Start pushbutton (safety relay) (S4). Note that for a further start, the start/stop switch (S1) on
the 3RW55 Failsafe soft starter must also be switched o and on again.
A.4.3 EMERGENCY STOP shutdown to SIL 3 STO with a 3RW55 Failsafe soft starter
with coupling of the digital input DI to the failsafe digital input F-DI
Together with an additional motor contactor connected between the 3RW55 Failsafe soft starter
and motor, two-channel STO applications can be implemented with the 3RW55 Failsafe soft
starter up to integrity level SILCL 3 according to IEC 62061 and PL e / Cat. 4 according to
EN ISO 13849‑1 (two-channel shutdown using the 3RW55 Failsafe soft starter in one of the two
channels). The safe signaling output (F‑RQ) of the 3RW55 Failsafe soft starter and the auxiliary
contacts of the contactor are monitored by a higher-level safety relay with SIL ≥ 2 (e.g. 3SK1).
The control commands at the failsafe digital input F‑DI of the 3RW55 Failsafe soft starter and at
the contactor come from 2 failsafe outputs of the higher-level safety relay.
Requirements
• Note the requirements in chapter 3RW55 Failsafe soft starter (Page 343).
• If the soft stop function is set (stopping time setting element set to > 0 s) and the EMERGENCY
STOP circuit is tripped, a "Missing load" error message may be indicated on the 3RW55
Failsafe soft starter. Use Reset to reset the error message.
• Main supply voltage (operating voltage) is present.
Example circuits
A.4 3RW55 Failsafe soft starter
SIRIUS 3RW55 and 3RW55 Failsafe Soft Starters
352 Equipment Manual, 02/2022, A5E35630887002A/RS-AF/006
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