Central Control Station Local IC Switchboard
Another of your duties as an IC Electrician is the
On ships with a central control station, a local IC
maintenance of the power distribution systems
switchboard is provided to energize the machinery
assigned to your division. Normally, the required
control IC systems.
inspections and cleaning are outlined on maintenance
The central control station switchboard receives
requirement cards (MRCs). When the inspection and
its normal power supply (120-volt, 60-Hz, 3-phase)
cleaning is due, you often think only of the main IC
from one of the ship's power panels. One of the ship's
switchboard. The small local IC switchboards located
lighting panels provides the emergency supply. The
in the engineering spaces and the remote sections of
switchboard also includes an ABT device, power
the ship are often forgotten. Auxiliary IC panels may
available indicator lights, and supply switches for the
have their own MRCs.
various machinery control systems.
Switchboard preventive maintenance will be
accomplished according to the applicable MRCs.
Steering Gear Room Local IC Switchboard
Corrective maintenance and troubleshooting will
usually consist of clearing grounds, repairing open
A local IC switchboard is usually installed in each
circuits, tightening loose connections, and finding the
steering gear room to energize all circuits associated
cause for blown fuses and overloads.
with steering-order and rudder-angle indicator
INSPECTION AND CLEANING
The switchboard receives its 120-volt, 60-Hz,
Loose electrical connections or mechanical
s i n g l e - o r 3-phase normal input from the
fastenings have caused numerous derangements of
steering-power transfer switchboard or one of the
electrical equipment. Loose connections can be
ship's power panels located in the steering gear room.
readily tightened, but it requires thorough inspection
A local emergency lighting circuit provides
to detect them. Consequently, at least once a year and
emergency power. This switchboard includes an ABT
during each overhaul, each switchboard, propulsion
device, power available indicator lights, supply
control cubicle, distribution panel, and motor
switches, and ACO switches.
controller should be de-energized for a thorough
inspection and cleaning of all bus equipment.
IC TEST SWITCHBOARDS
Inspection of de-energized equipment should not be
limited to visual examination but should include
Dead-front IC test switchboards are installed in
touching and shaking electrical connections and
the IC shops on most ships to provide a means of
mechanical parts to make sure that the connections are
performing operational tests and for troubleshooting
tight and mechanical parts are free to function. Where
space permits, a torque wrench should be used when
tightening bolts. Overtightening can be detrimental as
The test switchboards are normally set up to
undertightening. Refer to NSTM, chapter 075,
provide the following test outputs:
"Threaded Fasteners," for torquing procedures and
120 volts, 60 Hz, single phase
precautions. Table 3-1 contains torque values for the
more common bolt sizes used in switchboard
0 to 230 volts, 60 Hz, single phase
construction. Torque values are minimum and should
120 volts, 400 Hz, single phase
not be exceeded by more than 10 percent.
80 volts, 20 Hz, single phase
Be certain that no loose tools or other extraneous
articles are left in or around switchboards and
120 volts dc
distribution panels. Check the supports of bus work to
0 to 120 volts dc
be certain the supports will prevent contact of bus bars
of opposite polarity, or contact between bus bars and
The test switchboard may also contain ac and dc
grounded parts during periods of mechanical shock.
voltmeters, ammeters, test jacks, test leads, lamp test
Clean the bus work and the creepage surfaces of
sockets, a multimeter, and a fuse tester. These
insulating materials, and be certain that creepage
capabilities permit comprehensive bench testing of all
distances are ample. If damaged, taped switchboard
types of IC equipment.