depressing the ALARM ACKNOWLEDGE push
control. In this section, we will briefly discuss the
button. There are two levels of audible alarms at the
following control systems that are operated from the
EPCC. The first level is a horn that signifies a problem
EPCC:
that requires immediate action to prevent damage or loss
1. Diesel control and monitoring
of power. The second level is a bell for a problem that
2. Generator monitoring and control
needs correction as soon as practical.
3. Switchboard and distribution monitoring and
The EPCC controls the diesel for start-up and
control
shutdown. The SSDG can be shut down either under
normal or emergency conditions. Under emergency
4. Shore power monitoring and control
conditions, some diesel functions must be reset. Once
5. Engine fuel service system
the generator set is running, the EPCC controls what
type of voltage regulation will be used and how the
6. Auxiliary fuel service system
governor will control SSDG speed and load. The
7. Jacket water system
processor in the EPCC can control the operation of the
SSDG when the AUTO mode is selected.
8. Supervisory control system (SCS)
The EPCC operator can start the generator set if the
Again, refer to the EOSS, EOP, and appropriate
LOCAL/REMOTE switch is ON and all safety
technical manuals for a detailed description of these
conditions are met. Starting from EPCC can be
systems.
automatic or manual. As engine speed builds up, a fuel
pressure switch opens and de-energizes a pilot cracking
Diesel Control and Monitoring
relay. Once the engine is started and engine speed starts
to pick up, the governor will maintain SSDG speed.
Each ship's service diesel generator (SSDG) has
Initially the speed is controlled by the mechanical
sensors to provide remote monitoring of the diesel
governor until the limit setting is reached. Then, as
engine and generator. The sensor information can be
generator voltage builds up, the electrical governor
viewed either on meters or the DDI. Sensor signals are
takes over control. Although 115-volt ac power is
of two types: analog and discrete. Analog signals
required for this start sequence, the start can be
represent parameters such as fuel levels, temperature,
accomplished manually.
pressure, or rpm. Discrete signals indicate the
Under normal conditions, the operator can stop the
occurrence of an event, such as a breaker open, breaker
engine by pushing the engine STOP push button on the
closed, motor running, or motor not running.
local panel or depressing the remote PRIME MOVER
Commands are control outputs from the EPCC, and
STOP push button on the EPCC. During this stop
some action is expected in response to these signals.
sequence, the governor actuator is disconnected from
The EPCC monitors several conditions of the SSDG
the governor control circuit. Dropping resistors apply a
and displays them in several ways. The EPCC monitors
fixed voltage into the governor actuator, causing it to go
the diesel for the following conditions.
to the shutdown mode. As the engine loses speed, the
fuel pressure drops and opens a switch that deactivates
Engine fuel tank level, fuel pressure, and return
the shutdown condition.
temperature
The operator can initiate an emergency stop at the
SSDG manifold pressure
EPCC by depressing the EMERGENCY STOP push
Diesel fuel temperature
button. This is the same sequence as the normal
shutdown, except the air intake system is closed off by
turbocharger air pressure
activating the engine air box relay. After an emergency
stop, the operator must manually reset the air intake
SSDG lube oil discharge pressure, temperature,
solenoid. Until it is reset, an engine-mounted shutdown
and sump level
lockout switch will inhibit the engine from being started.
Engine speed and exhaust temperature
Generator Monitoring and Control
Alarms on the EPCC are of two types: hardwired
and processor generated. Hardwired alarms come
directly to the alarm display unit; they sound an alarm
The generator section of each SSDG is monitored
and light a lamp. The operator can cancel the sound by
for control and synchronizing. Transducers pick up
3-26
