When the load shedding control relay is energized,
take whatever action is needed to maintain the vital
its contacts pick up tripping relays in each main
s w i t c h b o a r d . The tripping relays complete power
circuits to the trip coils unselected main switchboard
400-Hz Power System
circuit breakers. The coils open the circuit breakers to
remove load from the line. Additionally, other loads are
The EPCC on the CG-47 class ships can remotely
similarly inhibited in load center switchboards by
operate a total of six 60/400-Hz static converters. Only
activation of tripping relays.
four converters are used on this class of ship. The
60/400-Hz converters on the DD-963 and DDG-993
class ships cannot be controlled from the EPCC. The
three converter units on these classes of ships each
provide a shutdown signal, a summary temperature high
The TOPS is an automatic protection system
signal, and a power available signal to the EPCC.
d e s i g n e d to prevent the loss of a GTGS due to
overtemperature. The TOPS control panel (shown in
On the CG-47 class ships, the converters may be
fig. 3-8) receives analog inputs, such as GTGS inlet
controlled from the EPCC only when the CCS IN
temperature, rpm, and kilowatt. These signals originate
CONTROL indicator is illuminated. Starting,
from the PAMISE. The control panel also receives
paralleling, and stopping the 60/400-Hz converters is
d i g i t a l inputs from the EPCC. These signals are
possible from the EPCC. Control and monitoring of
generator breaker status, bus tie breaker status, and
each static converter is provided by the following
shore power status. The control panel processes the
controls and indicator lights:
signals and provides a listing to the display unit. Based
upon the results of the analysis of the data, the control
1. 60-HERTZ POWER AVAILABLE - Ship's
panel issues the commands to close the bleed air valves
power is available at the converter input breaker.
and/or initiate load shed. The TOPS control panel will
2 . 400-HERTZ POWER AVAILABLE - The
converter is running. Closing of the converter output
breaker is enabled.
3. BUS TIE ENABLE - Converters are
synchronized and parallel operation is enabled. Closure
of the bus tie breaker is enabled.
4. SHUTDOWN - The converter is off. An alarm
or the operator has stopped the converter.
5. COOLANT FLOW LOW - Summary alarm for
all three liquid cooling mediums. The flow is low or has
6. TEMPERATURE HIGH - Summary of high
temperature shutdown alarms.
7. LOCAL CONTROL - Control of the converter
input and output breakers is at the converter master
8. CCS IN CONTROL - Control of the converter
input and output breakers is at the EPCC.
9. CURRENT - A meter that shows the converter
amperage to a maximum of 481 amperes.
Refer to the 60/400-Hz converter technical manual for
a detailed description of the operation of the static
Figure 3-8.--TOPS control panel.