give into mechanical failure. Center your attention in
ground, remove the short to restore the solenoid to
these areas. Electrical controllers do have electrical
proper operation.
problems, but most of the problems stem from the
REMOTE-INDICATING
VALVES
mechanical interface within the controllers. In general,
when a controller fails to operate or signs of trouble
A remote-indicating valve is a manually-operated
(heat, smoke, unusual noise, or smell of burning) occur,
valve that gives a remote indication of the valve's status.
you can find the cause of the trouble by a simple
One example of this type of valve is the primary manual
examination. This consists of using your sense of feel,
valves used in the fuel oil transfer and recirculating
sight, sound, or smell. At other times, however, finding
system on DD-, DDG-, and CG-class ships. These
the trouble will involve a more detailed process. See the
valves are equipped with open and close limit switches.
appropriate manufacturer's technical manual for a list
These switches provide open and close signals to the
of common troubles, their causes, and the corrective
fuel system control console (FSCC) and the associated
actions.
fuel oil local control panel indicator lights.
Imagine you are a GSE on a gas turbine-powered
A remote-indicating valve is a manual valve with
ship. You are sent to investigate an apparent electrical
t w o microswitches (limit switches). The valve is
controller system failure. You first press the START
manually opened or closed. When the valve reaches its
button (or, in the case of motor-operated valves, the
desired position, a tang or lobe attached to the valve stem
OPEN or CLOSE button). When this does not start the
actuates the appropriate limit switch. The switch sends
s y s t e m , you press the RESET push buttons (if
the signal to the console to illuminate the associated
applicable). Now you try to start the motor. If the motor
indicator light.
operation is restored, you will not need to perform
further checks. If the motor still fails to start, however,
T h e maintenance of remote-indicating valves
you must check the motor circuit for continuity. If the
includes inspecting, cleaning, testing, and
main contacts fail to close, you must check the control
troubleshooting the limit switches. The procedures used
circuit for continuity.
to maintain and troubleshoot microswitches (limit
switches) were discussed earlier in this chapter.
In the following paragraphs, we will guide you
through a procedure for troubleshooting a
ELECTRICAL CONTROLLERS
motor-controller electrical system. We will describe the
sequence of steps you should follow in locating a fault.
The most common electromechanical device used
Refer to figure 5-21 as we take you through this process.
in the Navy is the electrical controller (motor controller).
First, let's analyze the power circuit, and then the control
A motor controller functions to protect a motor from
circuit.
damage, to start or stop it, to increase or decrease its
speed, or to reverse its direction of rotation. The GSE
Power Circuit Analysis
rating is responsible for the maintenance of several
d i f f e r e n t types of electrical controllers in the
When no visual signs of circuit failure are clear and
engineering department.
an electrical failure is indicated in the power circuit, first
Electrical controllers can be found throughout the
check the line voltage and fuses (or circuit breaker), as
engine rooms of gas turbine-powered ships. They are
shown in figure 5-21. Place the voltmeter probes on the
used on space ventilation fans, motor-operated valves,
line side of the fuses, as shown at position A. (The
turbine enclosure cooling fans, and various pumps and
symbol VM refers to your voltmeter.) A line voltage
motors. The maintenance of these components and
reading tells you that your voltmeter is operational. It
systems is the responsibility of the GSEs. As a GSE, you
tells you that you have voltage to the source side of the
m u s t be able to recognize proper operation of a
line fuses. You can also check between the other lines.
controller and to take actions to correct any problem that
To check the fuse in line 1 (L1), place the voltmeter
arises.
across the line fuse, as shown at position B between
L1-L2. A voltage reading shows a good fuse in L1.
Controller Maintenance
Likewise, check the other two fuses between L1-L3 and
L2-L3. A no-voltage reading would show a faulty fuse.
Proper preventive maintenance lessens the chances
If the line fuses check good and the main contacts
of failure of electrical controllers. Since electrical
are closed, then check the voltage between terminals
controllers are electromechanical devices, they often
5-20
