6A1. General. A circuit breaker is a device
for opening an electrical circuit under load and
it can also be used as a switch for closing the
circuit. Circuit breakers may be either automatic
or nonautomatic in operation. They are
of two general types for direct current applications:
carbon tipped and quenched arc types.
The Navy designations for these types are ACB
(automatic carbon break), and AQB (automatic
quenched break) or NQB (nonautomatic
The type ACB is represented on submarines
by the I.T.E. type KN used on Electric Boat
Company vessels and the General Electric type
AL-2N used on Portsmouth vessels. The AQB
types are represented by Westinghouse breakers
and are used only on vessels of Portsmouth design
previous to SS 381. On later Portsmouth
vessels and on all Electric Boat Company vessels
they are replaced with fused switches.
6A2. Type ACB breakers. The ACB breakers (Figure 6-1)
used on submarines are live
front, two pole, manually operated and trip
free. They are enclosed for protection of personnel
and are fitted with overload and short
circuit protection and, in the case of the auxiliary
generator breaker, with reverse current protection.
They are equipped with a manual tripping handle which
may be used as a hold-in
device and, on the older less shockproof models,
can be turned to lock the breaker in. Since this
renders the breaker unable to open under overload,
it should never be left in the locked position after
the immediate danger of opening due
to shock has passed. The overload protective
device acts to trip the breaker after a time delay
when the current exceeds a certain value, usually
125 percent full load. The time delay is obtained
by an oil dashpot which consists of two accurately
ground disks in a bath of oil. When the
disks are close together, the oil film between
them resists the efforts of the tripping solenoid
to pull them apart. The time delay is inversely
proportional to the current and thus, on a large
current, the device trips faster. With currents
greater than about 800 percent of rated current
the solenoid pulls so hard that the whole dashpot
is lifted against a strong spring. This trips
the breaker in a short time and is known as
instantaneous short circuit protection.
Reverse current protection is provided on
the auxiliary generator breaker to prevent
damage to the engine should the generator attempt
to act as a motor when connected across the
battery. This device consists of a small torque
motor, that is, a motor that attempts to rotate
but cannot turn a whole revolution. The field
poles of the motor are energized by the line
current in one pole of the breaker and the armature
is energized by a coil connected across the
When the current is flowing in the normal
direction the motor tends to rotate in one
direction but is prevented from so doing by a stop.
Should the current in the breaker reverse, the
motor tends to rotate in the other direction.
When the current reaches a certain value, the
torque overcomes the pull of a calibrating spring
and rotates until it hits a plunger which trips
the breaker. The calibration range of the reverse
current trip is usually from 10 percent to
25 percent of the rated current. The action of
the ACB breaker in rupturing the arc is simply
a drawing out of the arc between the carbon
tips as they separate. The linkage is designed
so that the last points to separate are on the
carbon tips, thus preventing burning of the
current-carrying contacts which are silver tipped
for low contact resistance.
6A3. Type AQB and NQB breakers. Type
AQB and NQB circuit breakers used on submarines are dead front,
two pole, manually operated, and on AQB breakers are trip
fitted with short circuit protection. The arc in
this breaker is interrupted in the following manner:
As the contacts separate, the arc is drawn
into a steel box insulated from the rest of the
Figure 6-1. Type ACB circuit breaker.
breaker and slotted so that the are is separated
into several pieces, thus greatly lengthening it
and cooling it. Magnetic forces set up between
the arc and the steel box cause the arc to move
into the box.
The short circuit feature provided on AQB
breakers consists of a short circuit trip element
that is usually calibrated at the factory and is
not easy to adjust. The best practice is to replace
the element with a new one having the
desired tripping characteristics. When tripped,
the handle of the AQB breaker returns to a position
between OFF and ON. In order to reset it,
the handle must be pushed toward OFF first
and then to ON. NQB circuit breakers are entirely
manual in operation and open only when
the handle is turned to OFF. They have the
same arc-interrupting features as the AQB
All AQB breakers are provided with a manual means
of holding them in against overload and they can
be locked closed against
overload or shock. The locking devices should
never be engaged except when absolutely necessary
to prevent opening due to shock.
Figure 6-2. Type AQB circuit breaker, cover removed.
6B1. Fuses. Like circuit breakers, fuses are
used to provide protection from short circuits.
However, once the fuses have opened the circuit
because of a short circuit, they cannot be closed
and must be replaced. Fuses depend for their
action on the melting of a current-carrying strip
of metal by the heat generated by the current
in the strip itself. Fuses are generally selected
so that they will interrupt the circuit when about
200 percent of the rated current passes through
them. All fuses have a time delay action which
is inversely proportional to the current. This is
caused by the heat capacity of the fuse and
surrounding parts. Care should be taken when
installing fuses to see that good contact is made
in the clips as a high-resistance connection will,
generate heat and cause the fuse to blow at a
6B2. Fused switches. Fused switches are
used for disconnecting and connecting various
loads on the auxiliary power system and to provide
short circuit protection to the cables and
distribution panels. The type used on submarines
consists of metal boxes having fuses
with knife blade connectors attached to a sliding
piece inside the cover. When the cover is
closed normally, the fuse and attached blades
may make a connection across the split type
posts in the box; but pressing to one side before
closing the cover causes the blades to make no
contact and they are thus locked in the electrically
Fuses should never be replaced with fuses
of greater capacity than that shown on the
circuit diagram or marked on the label plate at
the fuse holder or on the switch box.
Fuse retainers are installed on all fuses that
can be jarred out of their holders by shock.
These may be insulating blocks held over a line
of fuses by thumbscrews or attached to the inside
of the cover of the box; or they may be
small clips of spring steel which increase the
tension of the fuse holder prongs. Fuse retainers
should always be replaced if they are removed for
C. LIGHTING SYSTEM
6C1. Description. The lighting system includes
the ship's service lighting system and the
port and starboard emergency lighting systems.
Each of the systems is a separate distribution
Power for the ship's service lighting system
on late type submarines is obtained from the
batteries through 2 lighting feeder voltage regulators
(see Section 6D1) and a lighting distribution
switchboard. On earlier ships, power for
this system was supplied by lighting motor
generator sets (see Section 4C1).
On ships that take the lighting power directly
from the batteries, a battery selector
switch has been incorporated in the lighting
distribution switchboard. This switch permits
selection of either the battery or the shore
connection as the source of power.
The feeders from the lighting distribution
switchboard run the length of the ship on both
sides and serve all regular lighting circuits
through fused feeder distribution boxes. Final
distribution to lighting fixtures and low-current
outlets is through standard lighting distribution
boxes with switches and fuses for each outgoing
The starboard emergency lighting system
is powered directly through 2 cutout switches
connected to the positive and negative end cell
terminal connectors of the forward battery.
These switches are connected to 13 lighting
units, a circuit to the auxiliary gyro, and to the
forward and after marker buoy circuits. A
branch junction box provides a connection to
the gyrocompass control panel for the alarm
The port emergency lighting system is directly powered
through cutout switches connected to the positive and
negative end cell
terminal connectors of the after battery. The
arrangement of this system is similar to that of
the starboard emergency system except for the
location of the circuits and the fact that there
is no gyrocompass alarm connection.
Each lighting unit consists of two 115-volt
lights, a protective resistor, and a snap switch,
all connected in series as they always operate
directly on full battery voltage.
6C2. Searchlight. The 12-inch incandescent
signal searchlight requires a 120-volt d.c.
supply. It is not considered a part of the lighting
system because the supply is taken from a
fused, double pole, single throw switch on the
I.C. switchboard and led to a pressure-proof
receptacle and snap switch on the bridge.
6C3. Maintenance.Pressure-proof type
searchlights that are left in place permanently
must be kept thoroughly clean and lubricated.
The pressure-proof feature consists of a free
flooding structure that drains rapidly after the
submarine surfaces. Power should not be applied to
the lamp until it has been out of the
water approximately 2 minutes. Special care
must be taken to keep all electrical connections
clean, the moving parts lubricated and the
aluminum surfaces painted to prevent corrosion.
CAUTION. Submerging with the light on
or shortly after it has been used will break the
searchlight bulb due to thermal shock. Diving
with the light on or turning it on while submerged
will blow the fuses.
D. LIGHTING FEEDER VOLTAGE REGULATORS
6D1. Description. Lighting feeder voltage
regulators are used on some ships instead of
motor generator sets, for the purpose of
maintaining the lighting system voltage at 120 volts
or below. Two units are used, one for the starboard
and one for the port lighting circuits.
These regulators are basically rheostats in
which a contact arm is moved, either manually
or by a motor, across a circular rheostat contact
face plate. Resistor tubes dissipate the excess
voltage in the form of heat. When the battery
voltage is high as, for example, during
charging, the supply to each of the lighting
voltage regulators which is obtained from one
half of the batteries may be as high as 175
volts. The rheostat is then adjusted to absorb
the difference between this supply voltage and
the desired 120-volt load-voltage. The rheostat
resistance is tapped so that it produces a voltage
drop of not more than 2 1/2 volts per step at
any current between 100 amperes and 12.5 amperes.
The rheostat is designed to dissipate 5500
watts at the maximum condition of a 55-volt
drop at 100 amperes. This rheostat will carry
between 12.5 amperes and 100 amperes through
a drop of 0 to 55 volts.
The assembly is actuated through a voltage regulator
element, known as an HIR regulator element,
and RAISE and LOWER relays.
The element is a voltage-measuring device that
balances the pull of its coils against the pull of
a coil spring. The RAISE and LOWER relays
serve to connect the rheostat motor so that it
rotates in one direction or the other in response
to the voltage sensitive element.
Essentially, the regulator element has 2
parts, one moving and the other stationary. The
moving armature carries a moving arm and is
supported by 2 flat hinge springs. The stationary
part consists of 2 stationary contacts with support
members and magnetic circuit parts. One
coil is mounted on each core. Each of these
coils is rated at 27.5 milliamperes and has a
resistance of 1950 ohms.
The coil spring is fastened between the
moving arm and the stationary member by a
lever which can be adjusted to obtain proper
spring tension. The lower end of the moving
arm carries 2 counterweights which statically
balance the moving arm in a vertical position.
The upper end of the moving arm carries
a double face, moving contact between a pair
of stationary contacts of the relays. These
stationary contacts are the R (raise) and L (lower)
contacts and can be adjusted to fix the operating
position and travel of the moving armature
in relation to the pole pieces.
The RAISE and LOWER relays consist of
two parts, one stationary, the other moving. The
stationary part consists of a base, core, coil, the
stationary main contact, blowout coil, and the
arc chute. The moving part carries the main
moving contact at its upper end and a counterweight
at its lower end for static balance.
The complete assembly is drip-proof in
construction and louvers are provided for the
escape of hot air. The maximum permissible
temperature rise on the rheostat resistor tubes
is 375 degree C.
CAUTION. Although the temperature may
not reach the maximum of 375 degree C, care must be
taken in handling or working around the equipment.
6D2. Manual operation. The correct procedure for
manual operation of the regulators is
as follows: Turn the control switch to the
MANUAL position. Pull the rheostat handwheel
to disengage the rheostat from the motor speed
reduction gears. The voltage of the load is
dependent upon the position of the rheostat arm.
Turning the rheostat handwheel in a clockwise
direction cuts out, or decreases, rheostat
resistance and raises the load voltage. Turning the
rheostat handwheel in a counterclockwise
direction cuts in, or increases, rheostat resistance and
lowers the load voltage.
6D3. Automatic operation. The following
precaution must be observed before turning the
control switch to the automatic (AUTO) position.
Always adjust the rheostat position manually to
give 120 volts on the lamp load. This
is the value of voltage that the regulator element
has been adjusted to maintain.
After manual adjustment to 120 volts, turn
the control switch to the AUTO position. The
moving contact of the regulator element will be
centered or floating between the front and back
stationary contacts. Both the RAISE and
LOWER contacts will be open.
When the load voltage rises, either by load
change or by increase of the charging generator
voltage, the element closes its lower contact.
This energizes the DECREASE relay, which
Figure 6.5. Schematic diagram of lighting feeder voltage regulator.
Figure 6-6. Lighting feeder voltage regulators and lighting distribution switchboard.
closes its contact in the motor field circuit. The
motor drives the rheostat arm in a counterclockwise
direction to cut in resistance and lower the
load voltage. The action is continuous until the
voltage is restored to 120 volts.
When the load voltage is lowered, the element closes
its contact. Provided the load voltage has not been
lowered to a value less than
50 volts, the increase relay closes its contact in
the motor field circuit. The motor drives the
rheostat arm in a clockwise direction to cut out
resistance and raise the load voltage. The action
is continuous until the voltage is restored to 120
NOTE. Large increases in load (over 50
amperes) should not be thrown on when the
control switch is set on AUTO as this may cause
the load and control voltage to fall below 50
volts, in which case the INCREASE and DECREASE
relays and rheostat driving motor will
Figure 6-7. Lighting feeder voltage regulator, top removed.
Figure 6-8. Top view of lighting feeder voltage regulator.
fail to operate. In general, when set for automatic
control, load steps should not exceed 50
amperes. Under manual control, precautions as
to amount of load increase are not necessary,
because the operator can take care of any load
change within the rating of the rheostat. In view
of the fact that overvoltage greatly reduces
incandescent lamp life, when using manual control,
an operating procedure should be established that
will prevent large amounts of overvoltage.
6D4. General maintenance.The equipment
requires only reasonable care to keep the
contacts and the control element free of dust or
dirt. The element contacts may be cleaned and
polished without removing the contacts. A clean
dry cloth should be used; emery cloth or other
abrasives should never be used.
Moving parts should be checked periodically
for free operation and to see that all moving
contacts are in proper alignment with their
stationary contacts. Main and auxiliary contacts
should close at approximately the same time.
The air gap between the moving and stationary
main contact should be approximately
1/8-inch. A screw on the bottom of the moving
arm is provided for adjustment of the air gap.
Lubrication of the rheostat motor should
be checked periodically. The motor is equipped
with 2 oil filler pipes, each of which has a screw
head plug to permit refilling.
6E1. Lubricating oil heaters. Four heater
immersion units, each rated at 220 volts and 500
watts, are installed in each of the 2 lube oil
heater assemblies. Each heater immersion unit
consists of 3 blades separately enclosed in a
steel sheath. The ends of the sheaths are brazed
to the terminal housing of the immersion unit
which is threaded for insertion into the heater
housing pipe assembly.
In operation, the oil circulates through the
heater housing pipes and, in its course, passes
over each of the heater immersion units. The
temperature necessary to bring the oil to its
proper viscosity is controlled by cutting in or
cutting out the required number of heaters, each
of which is provided with an ON-OFF switch.
CAUTION. The immersion units must not
be turned on unless oil is flowing. The units will
burn out quickly if current is applied while
they are not submerged in oil.
6E2. Air heaters. Portable 2-kw and 4-kw
blower type heaters are installed on each vessel.
The heaters are equipped with a switch providing
2 heating points. The switch positions are
marked OFF, LOW, and HIGH. A self-contained
fan is provided and is connected when
the switch is turned to one of the heat positions.
The 4-kw heater is rated 250 volts, at 16 amperes,
and has 4 insulated heater sections cast
in a circular fin type grid. Each pair of sections
is protected by a thermal cutout, actuated by
excessive sustained temperature and provided
with an indicator showing that the cutout has
tripped. The reset can be operated only after the
machine has cooled to a safe operating temperature.
The 2-kw heater is rated 250 volts, at 8
amperes, and is similar in construction to the
4-kw heater except that each heater section is
rated 500 watts, instead of 1000 watts.
Air heaters are fitted with protective devices
to allow operation at 345 volts. However,
during a long battery change at high voltage
they may be turned to OFF or LOW as a further
6E3. Hot water heaters. The hot water
tanks are of 20-gallon and 25-gallon capacity,
heated by rod type heating units that are
thermostatically controlled by magnetic contactors.
The 20-gallon tank is equipped with 2 heating
units, and the 25-gallon tank, with 3 heating
units. Each heating unit is rated at 4 kw at 275
volts, and will operate satisfactorily over a range
of 200 to 345 volts. Two watertight terminal
boxes are provided. The lower box affords access
to and contains the connections of the heating
units. The upper box affords access to and contains
the thermostat. The thermostat is adjustable for any
temperature range from 120 degrees F to
180 degrees F and operates on a change
of +- 5 degree F.
When properly vented, the tank is
completely filled with water at all times. The water
temperature is maintained in accordance with
the setting of the thermostat that controls the
coil circuits of magnetic line contactors in the
controller. When the water temperature falls
below the thermostat setting, the thermostat
closes the coil circuit, causing the contactors to
close and connect the heating units to the line.
When the water in the tank reaches the desired
temperature, the thermostat opens, opening the
contactors and disconnecting the heating
units from the line. Operation of each tank is
controlled by an ON and OFF tumbler switch
located on the magnetic line contactor panel.
6E4. Coffee urns. The urn consists of 2
cylinder-type containers, one mounted within the
other. An air chamber between the containers
prevents cooling of the coffee in the inner
container when fresh water is run into the water
The water tank is heated by 2 immersion
units, both controlled by a single
3-heat-indicating, reversible control
switch mounted in a
switch box located in front of the unit.
The immersion heating units are installed through the
back of the urn body in the lower part of the
water compartment. The unit heads, terminals,
and leads are housed under a removable cover
Each of the heating units has a rating of
1000 watts at 250 volts. The input of the urn,
at rated voltage, is 2000 watts on HIGH, 1000
watts on MEDIUM and 500 watts on LOW.
The urn capacity is 2 gallons of coffee and
4 gallons of water.
CAUTION. The heating units must not be
turned on unless the urn is filled with water and
must always be shut off or turned to LOW during
a long battery charge at high voltage, in
order to protect the units from the damaging
6E5. Galley range. The galley range consists
essentially of a cooking surface and an
oven. These units and their heating elements are
supported in the reinforced range body. The
cooking surface and the oven are each independently
controlled by two 3-heat reversible
indicating switches and each switch is protected
by a double pole cutout.
The cooking surface heating elements consist of
a nickel chromium resistor imbedded in
an insulating material within a seamless steel
sheath which is cast as a unit into the cooking
surface casting. The cooking surface has an area
of 19 inches by 18 inches and is rated at approximately
4000 watts on HIGH, 2000 watts
on MEDIUM, and 1000 watts on LOW. The
terminals are sealed to prevent air, moisture,
or grease from entering the heating coils.
The insulated oven compartment is approximately
17 inches wide, 18 inches deep,
and 14 inches high. The oven is provided with
an adjustable automatic temperature control
and indicator with a range between 200 degrees and
550 degrees F. Two heating elements are used; one is
located at the bottom, the other at the top of
The oven heating elements are of the same
construction as the cooking surface elements
except that they are enclosed in nickel chromium
tubing and are supported in a steel frame. Each
heating unit is rated at approximately 1500
watts on HIGH, 750 watts on MEDIUM, and
375 watts on LOW at 250 volts.
All heating elements are capable of operating
continuously at any voltage up to 345 volts
without detrimental oxidation.
The range is constructed for heavy duty
service and should require little electrical
maintenance. Spare heating elements, switches and
temperature control units are carried on board