Table 10.7
Shaft generator breaker trip flowchart
Yes
Shaft generator
breaker trip
Open SGB
SGB opened
No
Yes
SGB tripped
Alarm
1.
Open SGB:
When a trip is required, the controller activates the
Breakers > Shaft
generator breaker > Control > SGB open
output to open the breaker.
2.
SGB opened:
The controller checks whether the breaker has opened:
•
If the breaker has opened, the trip is successful.
•
If the breaker has not opened, the controller activates the
SGB opening failure
alarm.
10.4 Other SHAFT generator controller functions
10.4.1 Power take home (PTH)
Power take home (PTH) provides limited propulsion capacity to a ship by using the shaft generator as a motor to drive the shaft
propeller. For PTH, the reverse power alarms are inhibited. PTH allows the main engine to be turned off when the ship's propulsion
requirements are low. Alternatively, if the main engine fails, PTH allows propulsion and manoeuvrability according to the system
setup.
For PTH, the main engine must be disconnected from the propeller shaft, for example, by using a clutch.
PTH can only be activated in a SHAFT generator controller, and only when the shaft is running at nominal frequency. When PTH is
activated, the shaft generator consumes power, as it functions as a motor to drive the shaft propeller.
The PTH function can be configured to be activated by a digital input to the SHAFT generator controller.
Inputs and outputs
Function
I/O
Type
Details
Breakers > Shaft
generator breaker >
Command > PTH
mode
Digital
input
Continuous
When the input is activated, the shaft generator can be used as a motor to drive
the shaft propeller. Once the shaft generator breaker closes, the PTH function is
active until the breaker opens (even if the
PTH mode
input is deactivated).
Power take home can only be activated when the shaft generator breaker is open.
The input is ignored if the shaft generator breaker is closed.
Breakers > Shaft
generator breaker >
Command > Zero
pitch
Digital
input
Continuous
Optional. If the
Zero pitch
input function is configured, then the shaft generator
breaker (SGB) can only open during PTH if the
Zero pitch
input is activated.
The zero pitch input should come from the propeller-pitch control system.
Configure the input so that the propeller blades must be at zero pitch before the
input is activated. This ensures the minimum load when opening the shaft
generator breaker.
Parameters
Configure these parameters under
Configure > Parameters > Local power management > Shaft generator PTH mode > Open
point
.
DESIGNER'S HANDBOOK 4189340911K UK
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