Ss1-T Timer Start; Ss1-T Timing Quit; Safe State Of Ss1-T; Timing Precision - Danfoss VLT FC 280 Operating Manual

Operating Guide | VLT® Midi Drive FC 280

SS1-t Timer Start

6.3.2.4
If 1 of the following events is detected, SS1-t timer starts immediately:
Terminal 37 becomes low.
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Terminal 38 becomes low.
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SS1-t active command received on fieldbus.
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6.3.2.5

SS1-t Timing Quit

When SS1-t timer starts and does not expire, the SS1-t timer can be paused and reset when all of the following conditions are met:
When parameter 42-24 Restart Behavior is set to [1] Automatic, terminal 37 and terminal 38 are both high.
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SS1-t inactive command received on fieldbus.
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6.3.2.6

Safe State of SS1-t

The safe state of SS1-t is STO triggered before timer expires. If any internal fault is detected or external fault happens, the drive triggers
STO at any time.
Assess the risk of STO interrupting SS1-t.

Timing Precision

6.3.2.7
The timing precision is:
Lower limit = N × (1−0.1%)
Upper limit = (N+0.05) × (1+0.1%)
N is the set time (set in parameter 42-42 Delay Time), and the unit is seconds.

Safety Digital Input

6.4

Valid Voltage

6.4.1
The valid voltage range of terminal 39 should be 0 V, PELV.
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The valid voltage range of terminal 37 and 38 should be 0–24 V, PELV, refer to terminal 39.
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If the voltage on terminal 37 or 38 is over 30 V, the drive enters protection mode and triggers STO.
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If the voltage on terminal 37 or 38 is over 60 V, the circuitry of the drive will be damaged.
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Debouncing

6.4.2
Some devices, for example safety PLC, generates a test pattern on its output for stuck checking. These test patterns can interrupt the
drive. The drive can ignore these test patterns on terminal 37 and 38 if they stay at low level (≤1.8 V) for no longer than 5 ms.
To activate STO (or SS1-t) effectively and stably, keep the 2 channels both at low level for at least 1 s.
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NOTICE
NOTICE
Safety Functions
AQ381425076031en-000201 / 130R1223