Speed Control - Wartsila 31 Product Manual

13. Automation System
13.2.2 Stop and shutdown
A normal stop can be initiated locally, or remotely if applicable for the installation. At normal
stop the stop sequence is active until the engine has come to standstill. Thereafter the system
automatically returns to "ready for start" mode in case no start block functions are active, i.e.
there is no need for manually resetting a normal stop.
Emergency stop can be activated with the local emergency stop button, or from a remote
location as applicable.
The engine safety module handles safety shutdowns. Safety shutdowns can be initiated either
independently by the safety module, or executed by the safety module upon a shutdown
request from some other part of the automation system.
Typical shutdown functions are:
● Lubricating oil pressure low
● Overspeed
● Oil mist in crankcase
● Lubricating oil pressure low in reduction gear
At a stop or shutdown the fuel injection is disabled and the pressure in the high pressure fuel
line is instantly released.
Depending on the application it is possible to override a shutdown via a separate input. It is
not possible to override a shutdown due to overspeed or emergency stop.
Before restart the reason for the shutdown must be thoroughly investigated and rectified.
13.2.3

Speed control

13.2.3.1 Main engines (mechanical propulsion)
The electronic speed control is integrated in the engine automation system.
The remote speed setting from the propulsion control is an analogue 4-20 mA signal. It is also
possible to select an operating mode in which the speed reference can be adjusted with
increase/decrease signals.
The electronic speed control handles load sharing between parallel engines, fuel limiters, and
various other control functions (e.g. ready to open/close clutch, speed filtering). Overload
protection and control of the load increase rate must however be included in the propulsion
control as described in the chapter Operating Ranges.
13.2.3.2 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 normally 4%, which means that the difference in
frequency between zero load and maximum load is 4%.
13-6
Wärtsilä 31 Product Guide
Wärtsilä 31 Product Guide - a1 - 18 October 2016