Instrumentation for machinery, electrical, and periodically unattended machinery spaces: Chapter II-1
What the exam tests
This domain covers machinery alarms, electrical protection, and the additional arrangements for periodically unattended machinery spaces. The exam asks whether an alarm leads to the right action and whether the bridge can respond when no engineer is on watch.
Core rules
Periodically unattended machinery space (UMS) operation requires alarms and safety systems that protect propulsion, steering, electrical supply, boilers and auxiliary machinery. Alarms must be capable of being given to the bridge, and an engineer must be called when the alarm requires action. Fire detection and bilge-level alarms in the space are part of the UMS fit. The emergency generator must start automatically and connect to the emergency switchboard within 45 seconds; emergency power duration is normally 18 hours for cargo ships and 36 hours for passenger ships. Steering gear alarms and emergency steering arrangements must be tested. Alarm inhibition, override and silence functions must not remove the safety action.
Worked example
A UMS cargo ship suffers a blackout. The emergency generator starts but fails to close its breaker within 45 seconds. The bridge alarm shows the failure. The correct response is to treat emergency power as unavailable, start the emergency steering procedure if needed, and call the engineer. It is not acceptable to reset the alarm and assume the generator has connected because the engine is running.
Traps
Do not confuse an alarm with a trip; the alarm may require manual action while the trip protects the machine. Do not leave a UMS alarm inhibited after maintenance. Do not test the emergency generator only in manual start. Do not ignore a steering-gear hydraulic low-level alarm.