DDE-1000/4000 HP Q634 General Subjects Flashcards
In a closed-loop process control system featuring negative feedback, what is the function of the error detector within the controller?
The error detector computes the difference between the measured value of the controlled variable and the desired value (set point).
Which of the wave shapes shown in the illustration is termed a sinusoidal wave? Illustration EL-0088
A
Which of the following fixed temperature heat-actuated fire detectors is the most prone to false alarms?
bimetallic strip detector
What statement is true concerning the electrical diagram shown in figure “B” of the illustration? Illustration EL-0019
“R1”, “R2”, and “R3” are connected in parallel.
A precharged bladder-type accumulator used in a hydraulic system, can be potentially dangerous if __________.
the charging valve stem breaks while at normal working pressure
Three 12 volt, lead-acid, batteries connected in series will develop how many volts?
36 volts
If an air compressor is fitted with a hand-off-auto (H-O-A) control station, what statement concerning operation is true?
In the hand mode, the compressor will run continuously with unloading.
Which of the following statements is true concerning the gauge labeled “A” of the illustrated gauge manifold set? Illustration GS-RA-01
The gauge labeled “A” is a compound gauge and is usually color-coded blue.
What statement is true concerning the construction of watertight bulkheads?
The strakes of the bulkhead are horizontal and the stiffeners are vertical and the bulkhead must have increasingly greater strength towards the base.
Both the direction of flow and fluid flow rate of a variable displacement radial piston pump are determined by the relative positions of the __________.
floating ring and cylinder body
When troubleshooting a lead-acid storage battery, what is the best method for detecting a weak or dead cell?
comparing the specific gravity of the electrolyte in each cell
In a two-stage centrifugal air conditioning system, the liquid refrigerant passes through the condenser directly to what component?
economizer
When a refrigeration compressor is in the “off” cycle, the thermal expansion valve will react in what way?
it will continue to function as a result of the net balance of forces acting on the diaphragm
As shown in the illustrated diagnostic setup for locating a shorted field coil of a ten-pole synchronous motor, if 240 VAC/60 Hz is applied across the brushes, what would be the individual voltage drops measured across each field coil assuming that none of the field coils are shorted? Illustration EL- 0202
24 VAC
On a modern refrigerated container unit employing suction modulation for the purposes of capacity control and capacity limitation, what happens when the applied voltage and current draw associated with the normally open (NO) suction modulation valve located in the suction line both increase?
the valve will further close, raising evaporator pressure and lowering suction pressure
Alkyl benzene ISO 32 cSt synthetic refrigerant oil is miscible and suitable to use with which of the following refrigerants?
R-22
The safety heads of most large reciprocating compressors used in refrigeration systems are held in place by what means?
heavy coil springs
Which of the listed pressure-control valves would be used in a hydraulic system to temporarily divert some, or all of the pump discharge until the additional flow was required?
unloading valve
As shown in figure “B” of the typical ground fault relay shown in the illustration, what statement concerning the leakage current setting adjustment is true? Illustration EL-0223
Setting the leakage current for too low a value may increase the likelihood of nuisance trips and setting the leakage current for too high a value may result in incidental damage due to a ground fault.
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of __________.
pump cavitation
As shown in figure “A” of the digital multimeter screen shown in the illustration, what would be the significance of the symbol indicated by “1” being illuminated? Illustration EL-0047
the selector switch is selected for continuity/diode test and the secondary function push button
is toggled for continuity
Regarding an induction motor, what does the power developed by the rotor automatically adjust itself to?
power required to drive the load
By what means is an AC generator prevented from becoming motorized?
reverse power relay
What is one function of the movable cams in a drum-type winch motor controller?
regulate the speed of the motor
Why are removable sleeves installed on centrifugal pump shafts?
They can be economically replaced as they wear out.
Referring to the illustration what is the position of the three circuit breakers labeled in figure “A”, “B”, and “C” respectively? Illustration EL-0033
Circuit breaker in figure “A” is in the OFF position. Circuit breaker in figure “B” is in the ON position. Circuit breaker in figure “C” is in the TRIPPED position.
According to the illustration, which of the following conditions would most likely cause pump “A” to short cycle? Illustration GS-0173
The hydro-pneumatic expansion tank is operating with an insufficient air charge.
In the presence of an open flame or hot surfaces, chlorinated fluorocarbon refrigerants decompose and form what chemical substance?
phosgene gas
As shown in figure “B” of the illustrated self-contained recovery unit connection diagrams, what is the recovery method supported by the connection scheme? Illustration GS-RA-33
direct vapor recovery
On most commercial cargo vessels with a relatively small crew size and few users of the potable water system, how is the potable water system pressure maintained?
Cycling the potable water pump on and off by the action of the potable water hydro-pneumatic tank pressure switch in response to system demand changes.
Which of the following bilge pumping applications would most likely use a non-automated centrifugal pump under manual supervision?
Dry cargo-hold bilges
When a megohmmeter is used to test insulation, what condition causes the gradual rise of the pointer reading as a result of continued cranking?
the dielectric-absorption effect of the insulation
Which of the processes listed would be the most satisfactory method to use to lower the humidity of the air being circulated by an air conditioning system?
Cooling the air to a point below dew point, then reheating it.
How are fuses usually rated?
volts, amps, and interrupting capacity
No two drills from differing drill sets are of the exact same size, with the exception of the drills measured as 0.25 inch. These two drills are the 1/4 inch and the __________.
“E” drill
What is the physical state and pressure condition of refrigerant as it leaves a receiver in a typical refrigeration system?
high-pressure liquid
Four incandescent lamps are connected in series in a single circuit. If one of the lamp filaments burns out, what will happen to the other lamps?
all go out
In an electro-hydraulic steering system, damage due to rudder shock is prevented by __________.
relief valves
Referring to the illustrated motor ship fresh water cooling system drawing, what statement is true concerning the jacket water heater? Illustration MP-CW-06
The jacket water heater is used only when the engine is idle to keep the engine warm.
In a forced-feed lubrication system, what statement is true concerning lube oil reservoir/sump residence time?
The lower the oil level, the shorter the residence time, and the hotter the oil will be as delivered by the pump.
What is one major advantage of a diesel-electric propulsion plant?
excellent maneuverability
Which of the listed parts is used in a lobe-type rotary pump to allow for wear on the lobe edges?
Replaceable gib inserts
