Sto Commissioning; Activation Of Safe Torque Off; Deactivation Of Safe Torque Off; Sto Commissioning Test - Danfoss VLT Midi Drive FC 280 Operating Manual

Safe Torque Off (STO)
37
38
12
55
1 Safety device
Illustration 6.5 STO Wiring, External Supply
3. Complete the wiring according to the instructions
in chapter 4 Electrical Installation, and:
3a Eliminate short circuit risks.
3b Ensure that the STO cables are shielded
if they are longer than 20 m (65.6 ft) or
outside the cabinet.
3c Connect the safety device directly to
terminals 37 and 38.

6.3 STO Commissioning

6.3.1 Activation of Safe Torque Off

To activate the STO function, remove the voltage at
terminals 37 and 38 of the frequency converter.
When STO is activated, the frequency converter issues
alarm 68, Safe Torque Off or warning 68, Safe Torque Off,
trips the unit, and coasts the motor to stop. Use the STO
function to stop the frequency converter in emergency
stop situations. In normal operating mode when STO is not
required, use the standard stop function instead.
NOTICE
If STO is activated while the frequency converter issues
warning 8, DC undervoltage or alarm 8, DC undervoltage,
the frequency converter skips alarm 68, Safe Torque Off,
but the STO operation is not affected.

6.3.2 Deactivation of Safe Torque Off

Follow the instructions in Table 6.2 to deactivate the STO
function and resume normal operation based on the
restart mode of the STO function.
MG07A402
Operating Guide
WARNING
1
+
RISK OF INJURY OR DEATH
24 V source
Reapplying 24 V DC supply to either terminal 37 or 38
-
terminates the SIL2 STO state, potentially starting the
motor. Unexpected motor start may cause personal
injuries or death.
•
Restart
mode
Manual
restart
Automatic
restart
Table 6.2 STO Deactivation

6.3.3 STO Commissioning Test

After installation and before first operation, perform a
commissioning test of the installation using STO.
Perform the test again after each modification of the
installation or application involving the STO.
NOTICE
A successful commissioning test of the STO function is
required after the initial installation, and after each
subsequent change to the installation.
To perform a commissioning test:
•
•
Danfoss A/S © 10/2017 All rights reserved.
Ensure that all safety measures are taken before
reapplying 24 V DC supply to terminals 37 and
38.
Steps to deactivate STO Restart mode configu-
and resume normal ration
operation
1. Reapply 24 V DC Default setting.
supply to terminals 37 Parameter 5-19 Terminal
and 38. 37/38 Safe Torque Off=[1]
Safe Torque Off Alarm
2. Initiate a reset signal
(via fieldbus, digital
I/O, or [Reset]/[Off
Reset] key on the
LCP).
Reapply 24 V DC supply Parameter 5-19 Terminal
to terminals 37 and 38. 37/38 Safe Torque Off= [3]
Safe Torque Off Warning.
Follow the instructions in chapter 6.3.4 Test for
STO Applications in Manual Restart Mode if STO is
set to manual restart mode.
Follow the instructions in chapter 6.3.5 Test for
STO Applications in Automatic Restart Mode if STO
is set to automatic restart mode.
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