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8 SmartWire-DT
8.9 Programming
8.9.3.8 current limitation
176
Ctl_Req/Ctl_PLC
The Ctl_Req bit (Control requested: Control via PLC requested) will be set
automatically if PNU 928.0 = 1 (control via network).
After this, the application can be used to set the Ctl_PLC bit (Control by PLC)
in output bytes 0 and 4. It will not be possible to use the state diagram with
the control bits in output bytes 0 and 4 until this is done.
If bit Ctl_PLC = 0 when using control via the network (PNU 928.0 = 1),
the DS7-SWD soft starter will switch to fail-safe mode. This will make all
bytes +4 (Long) invalid (= 0). The DS7-SWD soft starter will switch to state
S5 (Switching Off). After this, a quick stop or coast stop will follow; then a
change to state S1.
Profiles 7, 8, 9 , and 11 can be used for current limitation with the DS7-SWD
soft starter.
Following is a description explaining how you can use this current limitation
function on DS7-SWD units.
Profiles 7, 8, 9
The PKE motor-protective circuit-breaker will only deliver the values of
currents; the DS7-SWD soft starter will carry out the actual current limiting.
Two parameters need to be configured:
•
Set the rated motor current in parameter PNU 210.0
•
In parameter PNU 281.1, set the motor current to a multiple of the
rated operational current
Profile 11
Profile 11 can be used to perform an external current measurement (e.g., via
an analog input to the PLC) in order to acquire values for the relevant
currents. Current limiting has to be programmed in the PLC with the settings
(current limits). If the set value is exceeded, the DS7-SWD soft starter can
freeze the ramp with bit 5 = 0 in order to limit the current.
If the current falls below the corresponding limit, bit 5 will have to be set to 1
so that the DS7-SWD soft starter will keep running up the ramp.
￫
This type of current limiting is not as precise as that achieved by
using a PKE motor-protective circuit-breaker connected
upstream.
However, it is usable in non-dynamic applications.
For additional information, refer to PNU 681.0 as well.
DS7 Soft starter 09/16 MN03901001Z-EN www.eaton.com
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