Figure 6-5, view A, shows the main motor control-
ler wiring diagram for the steering system shown in
figure 6-3. This wiring diagram can be used to trou-
bleshoot, check for proper electrical connections, or
completely rewire the controller.
SCHEMATIC DIAGRAM.—The electrical sche-
matic diagram describes the electrical operation of a
particular piece of equipment, circuit, or system. It is
not drawn to scale and usually does not show the relative
positions of the various components. Graphic symbols
from ANSI Y32.2 represent all components. Parts and
connections are omitted for simplicity if they are not
essential to show how the circuit operates. Figure 6-5,
view B, shows the schematic diagram for the steering
system main motor controller that has the following
electrical operation:
Assume 450-volt, 3-phase power is available on
lines 1L1, 1L2, and 1L3; and 2L1, 2L2 and 2L3; and
the receiver selector is set so that the motors are to idle
as standby equipment. Then turn the master switch
(MM and SPM push-button station) to the start position
to energize coil 3M. Coil 3M will close main line
contacts 3M, starting the servo pump motor. When
contacts 3M close, auxiliary contacts 3Ma and 3Mb also
close. Contacts 3Ma shunt (bypass) the master switch
start contacts to maintain power to coil 3M after the
master switch is released. When released, the master
switch spring returns to the run position, closing the run
contacts and opening the start contacts. Turning the
switch to the stop position opens the run contacts.
Contacts 3Mb energize latching coil CH, closing con-
tacts CH, and energizing coil 1M, which closes
main line contacts 1M to start the main pump motor.
(Solenoid latch CH prevents contacts 1M from opening
or closing due to high-impact shock.)
Before the motors can deliver steering power, the
receiver selector switch must be set to the appropriate
receiver, closing contacts RSSa and RSSb. Contacts
RSSa energize coil 2M, which closes contacts 2M to
supply single-phase power to the synchro system. Con-
tacts RSSb shunt the start and 3Ma contacts so that in
case of a power failure the motors will restart automat-
ically upon restoration of power.
In case of overload on the main or servo pump
motor (excessive current through IOL or 3OL),
overload contacts 1OL or 3OL will open,
de-energizing coil 3M to open line contacts 3M and
stop the servo pump motor. When line contacts 3M
open, contacts 3Ma and 3Mb open, deenergizing
Figure 6-4.—Ship's service generator and switchboard interconnections, single-line diagram.
6-7
