Woodward 721, Руководство по эксплуатации и калибровке

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721DSC for Marine Propulsion Application Manual 26004
Woodward 10
Speed Reference
The 721DSC provides local control of the speed reference with Raise Speed command (contact
input C), Lower Speed command (contact input D), Start Pos./Idle Speed selection (contact
input B), and Shaft Generator Operation command (contact input G). For remote speed
setting, the control provides a 4 to 20 mA Remote Speed Setting input. The Speed Reference
of 721DSC ramps to another set point with Raise/Lower rate when Raise/Lower Speed
command or Shaft Generator Operation command was input or Start Pos./Idle Speed
selection was changed. However, when the generator is synchronizing or when the load
transfer is being performed, the Load Transfer Rate is used to change the Speed Reference.
When the contact for Start Pos./Idle Speed selection input is opened, the Speed Reference is
fixed at Start Speed.
When the contact for Start Pos./Idle Speed selection input is closed, the Speed Reference
ramps to Idle Speed. When the Speed Reference reaches Idle Speed, it will be able to ramp to
another set point as directed by Raise/Lower Speed command or Shaft Generator Operation
command. The external Remote Speed Setting signal is enabled by closing both the Raise
Speed contact and the Lower Speed contact.
When the contact for Shaft Generator Operation is closed, the Speed Reference will ramp to
the speed specified with RATED SPEED set point and stay there. But the Raise Speed
contact and Lower Speed contact are enable while the engine is synchronizing for parallel
operation or performing Load Transfer. The Speed Reference returns to RATED SPEED
automatically after Load Transfer finished.
Load Transfer
This engine control system does not provide parallel operation in isochronous mode, but it can make two
engine
- generator sets distribute the load which has been loaded by one engine - generator set.
To transfer the generator load, the operator needs to open the generator circuit breaker (GCBx) of the
engine generator set to which the load will be transferred. (that is, if the load will be transferred from the
starboard engine to the port engine in drawing 9951
- 626, GCB 2 must be opened, and vice versa.)
Connect the tie circuit breaker (TCB in drawing 9951 - 626). When one of the 721 controls detects that the
GCB x AUX contact (contact E) is open and the TCB contact (contact F) is closed, this control will switch
the operation mode from isochronous mode to KW droop mode to perform load transfer. The 721 control
whose GCB has been closed, will not switch operation mode , and continues to run in the isochronous
mode.
Synchronize both engines and close the GCB which was opened first in this load transfer procedure. Next,
transfer the engine
- generator load to another engine by raising the speed set point of the 721 control
working in the load transfer mode.. When the load levels of both engines are appropriate, open the TCB to
switch the engine operation mode to the isochronous mode.
Now, the load transfer has completed.