Safe State; Internal And External Fault; Fault Reaction - Danfoss VLT FC 280 Operating Manual

VLT® Midi Drive FC 280
Operating Guide
Table 23: Safety Functions Combination in Drive
FC 280
Safety digital input
1 * means default value.
Via fieldbus only.
2
Via digital input only.
3
Via both trigger sources.
4

6.2.2 Safe State

The safe state of the drive is STO achieved or power off.

6.2.3 Internal and External Fault

Internal fault
The diagnosis mechanism of the drive detects the internal fault inside the drive.
Normally, an internal fault is caused by:
• EMI.
• Random failure of components.
• Harsh environment condition.
• Other systematic errors.
When an internal fault is detected, the drive reports an alarm and switches to the safe state. To reset the drive, clear the alarm man-
ually or recycle the power supply.
External fault
External fault is the fault caused by invalid external input which includes:
• Discrepancy on safety digital input.
• Safety fieldbus communication errors.
• Fieldbus master, for example a PLC, forces the drive into safe state.

6.2.4 Fault Reaction

When an internal fault is detected, the fault reaction is STO. When an external fault happens, the fault reaction can be defined via
setting parameter 42-30 External Failure Reaction to STO or SS1-t.
Assess the risk before using SS1-t as external failure reaction.
6.2.5 Recovery from Safe State
6.2.5.1 Recovery from Safe Function Triggered Normally
Restart behavior of safe digital input
56 | Danfoss A/S © 2022.02
Safety fieldbus
Disabled*
Disabled* None
(1)
STO STO
SS1-t SS1-t
C A U T I O N
Enabled
(1)
STO
(2)
STO
(3) (4)
SS1-t
(3) (4)
AQ381425076031en-000101 / 130R1223
Safety Functions
and SS1-t
(2)
and SS1-t
(2)
and STO
(2)