24
AUTOM ATIC CONTROL U N ITS , OM D20 0 A N D 3 0 0
5.2.7
OMD200 and OMD300 outputs
5.2.7.1 Opening/closing command to change-over switches, X21 (DO1-DO2) and
X22 (DO3)
These outputs command the change-over switch to open and close Switch I or Switch II.
To guarantee the highest-level safety OMD_ monitors the correct operation of the change-over switch
after a command has been sent. If the feedback of the switch status is not received within 3 seconds of
the sending of the command, the device considers it as a failed command and operates as follows:
An alarm is generated: DO6 activate.
Alarm LED is blinking.
Alarm is set off by pushing the AUTO key. After that the device is always in the Manual Mode to
prevent unwanted operation of the change-over switch.
Exactly the same operations are performed on the secondary line (LN2-Switch II) during the back
switching sequence.
5.2.7.2 Gen-Set start/stop, X23 (DO5)
Gen-Set start and stop is handled by a bistable relay. When the relay contact Start (X23:1) is closed, the
generator is started. When the relay contact Stop (X23:3) is closed, the generator is stopped.
5.1.7.3 Alarm signaling, X24 (DO6)
When the relay contact Alarm (X24:3) is open and contact OK (X24:1) is closed, the automatic transfer
logic is enabled. If the relay contact Alarm (X24:3) is closed and the contact OK (X24:1) is open the
automatic transfer logic is disabled and an alarm is active.
5.2.8
OMD200 and OMD300 inputs
5.2.8.1 Switch status input, X31:2 (DI1), X31:3 (DI2)
These two inputs are connected to change-over switch auxiliary contacts. Input X31:2 (DI1) is con-
nected to LN1-Switch I and input X31:3 (DI2) is connected to LN2-Switch II (Switch I / II open = input in-
active, Switch I / II closed = input active). Auxiliary contacts are in-built in motorized OTM40…125_
CMA_. If OMD_ is used with motorized OTM160…2500_CM_, use always type OA1G10 auxiliary contacts
with DI1 and DI2. See the wiring diagrams on Figure 5.1, Figure 5.2, Figure 5.4 and Figure 5.5.
5.2.8.2 Force manual, X31:1 (DI3)
When the handle is attached this input is closed and OMD_ is forced to Manual Mode. To set the OMD_
back to the Automatic Mode the handle must be removed and the AUTO key pushed (Auto LED is ON).
