DSC - Inputs
Page 20 of 80
The autopilot acknowledge signal may be output directly by the autopilot
system as a dry contact. Alternatively an external relay may be used in
order to change an autopilot’s acknowledge or clutched output signal from
a voltage to a dry contact.
CAUTION:
The steering control system will not transfer to control of the rudder
position to the autopilot unless a contact closure is present across the
autopilot acknowledge terminals.
Commissioning
There are no specific commissioning procedures associated with this
connection.
1.3.6 Backup NFU System
Description
These connections allow for a backup NFU jog lever to be directly
connected to the HPU’s directional solenoid valve. The backup NFU
system’s power supply and command signals are isolated from the DSC
through the use of a directional solenoid control relay. Whenever the
control relay is de-energized the backup NFU system, including its power
supply, is directly connected to the directional solenoid valve (see 1.4.1
).
The directional solenoid control relay also provides a dry contact output to
indicate the status of the backup NFU system. This output is described in
section 1.4.5
.
In case of a failure in the main power supply to the DSC, the backup NFU
system is automatically made operational. The backup system can also
be invoked on demand by disconnecting the main power supply to the
DSC or by turning off the DSC power switch on the side of the DSC
enclosure. The DSC can be configured so that the backup NFU system
will also be activated whenever the JOG mode of steering control is
selected at the main steering control station.
The backup NFU system is only capable of outputting on-off signals to the
directional solenoid valve, therefore the backup NFU system can not
provide acceleration and deceleration of the steering gear. For operation
with a proportional directional solenoid valve, a rheostat is connected in
series with the backup system’s power supply. This rheostat provides
current limitation and rudder speed control for the backup NFU system.
See drawing 5.4
DSC Backup NFU Simplified Schematic.
See also: 1.4.5
Backup NFU Status Output
Doc No.: MAN01504, 20-02-06 DSC 100 & MCP 100 Manual
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