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14.2.3.3 Emergency stop mode
The sequence of engine stopping in emergency stop mode is similar to shutdown mode and
also the pre-chamber gas is de-activated immediately upon stop signal.
Emergency stop is the fastest way of manually shutting down the engine. In case the emergency
stop push-button is pressed, the button is automatically locked in pressed position.
To return to normal operation the push button must be pulled out and alarms acknowledged.
14.2.4
Speed control
14.2.4.1 Generating sets
The electronic speed control is integrated in the engine automation system.
The load sharing can be based on traditional speed droop, or handled independently by the
speed control units without speed droop. The later load sharing principle is commonly referred
to as isochronous load sharing. With isochronous load sharing there is no need for load
balancing, frequency adjustment, or generator loading/unloading control in the external control
system.
In a speed droop system each individual speed control unit decreases its internal speed
reference when it senses increased load on the generator. Decreased network frequency with
higher system load causes all generators to take on a proportional share of the increased total
load. Engines with the same speed droop and speed reference will share load equally. Loading
and unloading of a generator is accomplished by adjusting the speed reference of the individual
speed control unit. The speed droop is typically 4%, which means that the difference in
frequency between zero load and maximum load is 4%.
In isochronous mode the speed reference remains constant regardless of load level. Both
isochronous load sharing and traditional speed droop are standard features in the speed control
and either mode can be easily selected. If the ship has several switchboard sections with tie
breakers between the different sections, then the status of each tie breaker is required for control
of the load sharing in isochronous mode.
14.3
Alarm and monitoring signals
Regarding sensors on the engine, the actual configuration of signals and the alarm levels are
found in the project specific documentation supplied for all contracted projects.
14.4
Electrical consumers
14.4.1 Motor starters and operation of electrically driven pumps
Motor starters are not part of the control system supplied with the engine, but available as loose
supplied items.
14.4.1.1
Engine turning device (9N15)
The crankshaft can be slowly rotated with the turning device for maintenance purposes and for
engine slowturning. The engine turning device is controlled with an electric motor via a
frequency converter. The frequency converter is to be mounted on the external system. The
electric motor ratings are listed in the table below.
Summary of Contents for 31SG
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Page 58: ...Page 58 Fig 6 4 Gas valve unit reference P I diagram DAAF051037D...
Page 60: ...Page 60 Fig 6 7 Gas valve unit P I diagram open type DAAF085795A...
Page 64: ...Page 64 Fig 7 2 Lubricating oil system single engine wet sump DAAF301501B...
Page 65: ...Page 65 Fig 7 3 Lubricating oil system Gas multiple engines wet sump DAAF301500A...
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Page 77: ...Page 77 Fig 9 1 Example diagram for multiple main engines DAAF301505A...
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Page 132: ...W rtsil 31SG Product Guide Page 132 21 2 Collection of drawing symbols used in drawings...