3. The annunciator target still reads OUT.
Sequence of Operations
When the defective lamp is replaced (or the fault in
The operations of the supply control and telltale
the primary circuit is corrected), the following events
panel are easily seen by following the schematic
diagram in figure 4-21. For simplification this
schematic shows only one of the five running lights; the
1. The relay coil is energized and relay contacts X
operation is the same for all five.
and Y are opened.
When the primary filament of a running light is
2. The annunciator coil is then de-energized,
lighted, relay contacts X, Y, and Z are open; the indicator
opening contact Z.
lamps, annunciator, and buzzer are not energized. The
3. The target indicates RESET. The secondary
reset switch must be kept pointing in the RESET
filament is now de-energized, and the indicator
(vertical) position under normal conditions, or the
lamps are lit.
buzzer will not be energized when a failure occurs.
4. The reset switch is returned to the RESET
If the primary filament circuit is opened or the
filament burns out, the following events will occur:
5. The indicator lamps go out.
1. The relay is de-energized, causing contacts X
and Y to close.
6. The entire unit is again operating in the normal
2. Then the secondary filament and the indicator
lamps are lighted, and the annunciator target
A dimmer control panel connected as shown in
drops to the OUT position, closing contact Z,
figure 4-22 is provided for dimming the running lights.
and the buzzer sounds.
This panel provides only one dimming position. In the
dim position the visibility of the mastheads, side lights,
When the RESET switch handle is turned to the
and the stern light is reduced considerably. The
horizontal position, the following events will occur:
sequence of operation of the telltale panel is the same
1. The buzzer is silenced.
whether the running lights are in the bright or dimmed
2. The indicator lamps remain lighted.
Figure 4-21.--Running light, supply, control, and telltale panel schematic diagram.