15 August 2002
all pumps, gates and valves, and the valve position indicators in a suitable panel or
Power Demand Range. The following tabulation presents probable
range of electrical power demand for pumping the several classes of graving docks.
These figures may be used for preliminary purposes of study and/or design, but are only
indicative of the ranges to be expected.
Range of kW
Class of dock
750 to 1,250
Destroyer or frigate
950 to 1,300
1,300 to 3,000
Carrier & Auxiliary
3,500 to 5,000
Main Pump Motors. Main pump motors should generally be of the
windings, except where variable pitch impeller type pumps are used. In this latter case,
use synchronous motors with reduced voltage starting where required. In general,
operate these motors on a minimum of 2,400 volts, and at greater voltage where
economically sound. Use drip-proof construction, and provide space heaters to heat the
windings to approximately 15 degrees C (5 degrees F) above the ambient room
temperature whenever the motor is disconnected from its voltage supply.
Drainage Pump Motors
. Drainage pump motors should
be of the squirrel
cage induction type, operated at 460 volts and at higher voltage where economically
sound. Provide reduced voltage starting when required by design conditions. Provide
dripproof construction and space heaters for the windings of the pump motors.
Other Motors. Provide sump pumps, sluice gates, gate valves, sewage
pumps, and ventilation fans with squirrel cage induction motors operating at 460 volts.
Motors should be dripproof or totally enclosed.
Switchgear. Install high voltage protection and distribution equipment in
a steel-enclosed, dead front assembly of switchgear. Carefully coordinate interrupting
ratings of the gear with the systems to which connection is to be made. Construction
should be dripproof, and space heaters should be provided to maintain the
compartments of the switchgear approximately 15 degrees C (5 degrees F) above the
ambient room temperature when the pumping plant is not in use.
Grounding. Provide grounding systems for all electrical equipment
frames, enclosures, and conduit systems.