Safety Functions; Safe Torque Off (Sto); Overview Of Safe Torque Off (Sto); Sto Triggered By Di - Danfoss VLT FC 280 Operating Manual

Operating Guide | VLT® Midi Drive FC 280

Safety Functions

6.3

Safe Torque Off (STO)

6.3.1
6.3.1.1

Overview of Safe Torque Off (STO)

Safe Torque Off (STO) prevents the drive from generating the energy that is required to rotate the motor, thus ensures the safety of the
system in emergency situations.
The STO function in the drive is controlled via redundant safety digital input (terminals 37 and 38) or/and safety fieldbus. When STO is
activated, the power supply on the high side and low side of the IGBT gate driving circuits is cut off.
f
A
1
Figure 31: Safe Torque Off
1
Activation of Safe Torque Off
A Actual frequency
6.3.1.2

STO Triggered by DI

To enable safe DI as STO input, set parameter 42-20 Safety Function T37/T38 as [0] STO.
terminals 37 and 38 are energized.
Table 25: STO via DI
Terminal 37
High
Low
Low
High
1) Voltage range is 24 V±15%, with terminal 39 as reference.
2) Torque is present only when the drive is running.
3) Open circuit or the voltage is within the range of 0 V ±1.5 V, with terminal 39 as reference.
62 | Danfoss A/S © 2024.10
t
2
Terminal 38
High
Low
High
Low
2
Motor standstill
Table 25 shows STO statuses based on whether
Torque
Yes
No
No
No
Safety Functions
shows the STO architecture.
Figure 31
Warning/alarm
None
W68
W252
W252
AQ381425076031en-000201 / 130R1223