General Flashcards
Where are CSMPs exported to?
fleet logistics system
What is the theory of the PGA-EG backup control in relation to fuel and current?
Increased fuel causes a decrees in current reverse-
What is the theory of the PGA -eg backup control in relation to fuel and current
Increased fuel causes a decrease in current Reverse-acting
How does a magnetic speed pickup MPU work?
Produces an output voltage when any magnetic material moves through the magnetic field at the end of the pickup.
When 3 factors effect the output voltage of the MPU?
Surface speed, voltage in increased gap, vol waveform is determined by size and shape of gear tooth in relation to the pole piece.
What is the distance of the pick up and the gear normally set at?
.25 and 1.02mm ( .010 and .40 in)
What is the minimum output voltage RMS at the pick ups lowers settings
1.5 vac
What direction will be compensated for a negative error signal and a positive error signal
Negative to port positive to starboard
what type of cathodic protection is on the 110s and 225
CAPAC
Which relay must be Mannual reset in the water circuit of a boiler
The #2 low water relay
What switch monitors steam demand
Operating limit pressure control switch
What switch is a safety back up for the operation limit pressure switch
High-limit pressure control switch
What does the high and low pressure control switch do?
Controls the firing rate upon steam demand
What does the open damper purge switch check
Test full airflow through the boiler during the pre purge stage
What does the open damper purge switch check
Test full airflow through the boiler during the pre- purge stage
What is the maximum depth for under cutting
1/16 in to 1/64
What megger voltage should be used for field windings, 1000 or 500
500v
What is the purpose of the 4-20 MA transducer
Convert measured pressure into an electric output
What is the major mechanical component of pressure transducer
A diaphram
What is the 2 wire system voltage
28 volts
What is the allowance change request ACR form?
Navsup 1220-2
What is the four wire system voltage?
115volts ac
Name two types of metals used for RTDs
Nickel and platinum
What are the three types of RTDs
Therowell bareblub, and embedded
What is the relationship of resistance to temperature
Positive temp coefficient. Increase in resistance increases with an increase in temperature
What are the wire colors if k and j type thermocouples
Type J. White / red
Type K red/ yellow
What are the ranges of J and K thermocouples
K 40-530
J 0-1200
J and K metals?
K chromell and allumel
J iron and constantum
What is the type of cables used with type j and k
LSTCKX. And LSTCJX. Or LSTCTS
What is the stick off voltage used in CT syncros?
2.5 v
115 volt circuit at electrical zero what will s2 read?
52 volts
What 2 leads are swapped in a syncro to change rotation.
S1 and s3
What 2 leads are swapped to make a 180 degree change ?
r1 and r2
What is the designation for wind speed and wind direction circuits
HE and HD
What must be done to the Aerovane circuit if to vanes are used?
The 1150 ohm resistors must be removed.
With a single Aerovane circuit what is the voltage per MPH, KPH and knots?
1056 CDC mph
0656 CDC kmh
1215 vdc knot
Wind speed formula
Rpm x .04839 miles
Describe the salinity cell in water makers
Measures free ions in between 2 metal plates. Higher impurities will increase current
During normal operation is making a good water is the dump solenoid energised or D energized
Energized
What is the thermistor used for?
To compensate for increased temperature of water with a logarithmic temperature coefficient. Increased temperature decrease resistance equals conductance
FD FR F FZ and HF mean
Flooding CO2, high temp, security airflow indication
What is the intensity of the homing beacon?
1500 foot candles at 330 degrees
What is the step voltage for the homing beacon ?
115/ 32 volts
What is the direction of the dead edge lights and their step Voltage
Omin directional 115/12 v
Direction of line up lights?
Bi directional 115/6.5
Where are the vertical drop line up lights on the step voltage
Aft strbd below landing deck 115/11v
How far apart are the HIFR lights
40 ft
What side of the ship are the HIFR lights on?0
Port
What is the maximum difference between rudder angle indicators?
+/_ 2 degrees
What is the variable voltage of the wiper system
68 vdc 115vc fixed 40vdc
What are the three types of wiper system
Rotary, pendulum and straight line
On batteries what is the compensation on Hydra meter for increased decreased in temperature relative to 80°F
3° either direction either direction subtract .0001
How does the equalizing charge on a battery work
A periodic extended normal charge given on at the finishing rate to ensure that our sulphate is driven from the plates and that the cells are restored to the max specific gravity
What is the polarization indexed test?
Megging the windings of a motor for 10 mins constantly and writing the results of the first and last minute.
What is a floating charge
Is a chargering source maintained at 2.13 to 2.17 vdc per cell of battery
What is the maximum difference in airgap readings between measurement under all the field poles of a motor or generator
10%
What is the proper tool for measuring air gaps
Machinists tapered feeler guage
Name the two types of bearings in motors and generators
Roller and sleeve bearings
What are the proper distance from brush holders in relation to the commentator
1/8 inc in max and 1/16 min
What grade of sandpaper should be used in seating brushes
80 gritt
What direction should the paper be applied
Opposite the rotation
What direction should the rotor be turned?
In the direction of rotation for 5 to 6 revolutions
What is approved material for sowel pins
304 stainless
What is the preferred method for motor pump alignment
Indicator reverse Method
What is it common type of switchboard circuit breaker
AQB
What does the AQB-LF c/b contain
Fused over current protection
What does the NQB the cb lack that the AQB contains
An automatic tripping device
Why are some characteristics of the day ALB circuit breaker
Designed for low voltage 120 V a C or DC has automatic trip in overload
What is the difference between active and passive ground detectors
Active sends a reference voltage through the system while a passive detector measures a difference of potential to ground
What is the formula for determining power factor
ExIx
1.73/1000= kva
State the relationship of current to voltage to and current to resistance in an electrical circuit.
Current Is directly proportional to the voltage and inversely proportional to resistance
What does the left handed rule determine direction of?
Magnetic lines of flux
Define inductance
And electrical conductor of that opposes a charge in current
Can AQB breakers be held closed in a tripping state
NO
Name three types of Transformers
Iron core, air core and softiron
Which is used for a high-frequency applications over 20 killer hurts
Air core
What term describes the primary and secondary winding relationship in a transformer
Mutual induction
In an open delta transformer con- figuration what is the output reading
57.7%
Define capacitance
The ability for a circuit or a body to store a electrical charge equal to accumulator charge divided by the voltage
Define inductance
The production Of magnetization in a body by the proximity of a magnetic field
The parts of the compass element
Gyro spare vertical ring support plate follow-up system components the compass card
What is the primary difference between mark 27 gyro and the other gyro used in the Coast Guard
It does not read pitch and roll contains a liquid ballast
Define rigidity
The ability to maintain a fixed position in space
Where are the weights applied to make a Gyro North seeking
On the bottom of the vertical ring and on the west side of the Gyro rotor heavier weight on the west side
What is the nominal time value allowed for load balance to return upon energizing a large load to a circuit
2 seconds
What is the in
NSTM for electrical distribution
320
How are casualty power cables labeled in relation to phase
Abc 123 red black white
At what percentage of voltage drip and for what period of time are ABTs set at
60 to 70 percent at .3 to .5 sec
When will the ABT’s restore to normal power
85 percent to. 90 percent of voltage
What is the max horsepower of motor in a 440 V motor that can be fused
7.5hp
What are the three types of fuses
Normal blowing, time lag and very high-ampere interrupting capacity
What is a common characteristic of new shipboard cable
They are all low smoke cables LS
What percent over the load should fuses be in transformer and inductive load circuits
125 percent
What about motor load circuits
250 to 400 percent
What are the two navy service classifications of motors ?
A and C
What are three types of motor ratings
Continuous, intermittent, and short time duty
What is the general characteristics of most motors on ships
They are Polyphase induction motors
Definition of an induction motor
A primary wind is wired to the power supply which uses a rotating magnetic field into the second winding which in Turns creates a magnetic field which moves the rotor causing mechanical action
What is slip?
The actual speed of the rotor in realation to the rated synchronous Speed
What term describes the speed of rotation
Synchronous speed
What is the formula for slip
120 times the incoming power frequency divided by the number of poles in the primary winding
What are for types of DC motors
Shunt series compound and stablized shunt
Define shunt
Field coils connected in parallel with the armature. Used on moderate torque start up and speed which is not affected by change in load
Define series motor
Field coils in series with armature have high starting torque
Define compound motor
Has both series and parallel windings to armature
Define stablized shunt
Similar to compound except the series winding is lower strength to allow for motor consistency with change in load
What is the ideal specific gravity for lead acid batteries
1.210 to 1.220
What is the maximum specific gravity for lead acid batteries?
1.350
What is the min specific gravity for lead acid batteries
1.210
I’m nonmetallic hulled ships how offten are the ground straps be inspected
Annually
Why is N STM reference for working on energised circuits
300 2.5.2
At what voltage amperage rating may dead right fuses be gremoved without de energising the load?
480 volt 10 amp
How many Power strips can be on a circuit
One and the circuit must be a one Isolate receptacle circuit
Which type of ground detector uses lights and voltmeters
Passive ground
Which type of ground detector applies dc voltage between and operating power system and-ground
Active ground
When taking installation reading what voltage should you set the megger at
500 vdc
What is the DC high potential test
A test where dc voltage is applied in steps and current leakage is measured to identify grounded or potentially failing insulation on motors
What is the Ac high potential Test what is the major precaution.
A test which induces A ac voltage through a motor or generator to detect defective insulation it is a more rigourous test and should not be done except at repair facility due to possible damage to equipment and personnel
How afternoon should shock mounts be inspected
Every six months
What are the maximum allowed spices for a cable
2
What metal should be used on plating be on steel bolts used for electrical connections
Zinc
What are the tolerances for a brush holders distances from the commentator
No more than 1/8 ad no less then 1/16
Name three methods of determining the correct neutral position for motors and generators
Mechanical method, reversed rotation method and the kick method
What are two tool shapes for under cutting mica
V and u
Which one requires Chamfeting only upon completion
U
What should be done upon completion of undercutting of Mica
The commutator should be Stoned
Name two types of batteries
Primary cell Non re- chargeable and second cell rechargeable
Name of primary cell types
Lead acid, alkaline, nickel cadmium, zinc
Name types of second cell types
Dry cells, lithium cells
Define a battery
A unit consisting of positive and negative plates. Separators a cell cover and electrolyte
What is the discharge Rate of a a battery
10 hr discharge rate of a battery is equal to the consistent current in amps which the battery starting with an initial electrolyte temperature of 27°C 80°F can supply continuously for 10 hours before the voltage has dropped to the low voltage limit which the discharge should be start
What is the ampere -hour capacity
The amount of hours the battery will deliver at that rate before voltage drops below it specified number of limiting voltage capacity is greater when discharge is slow
What is the normal pressure of a sealed battery and what is it relief point
2-3 psi and 4-5 psi
What happens to current flow on a charging battery
it is reversed
How high above the separator should the electrolyte be ?
9mm or 3/8 in
How long will dry cell batteries last in storage
Up to 2 years
How long will wet batteries lasted storage
They need to be re-charged every 4 to 6 months
What is the expected life range of a lead acid battery if taking care of properly
Four years according to NSTM chapter 313
What does the floating ball charge colours mean in percent
Red white and green equals 90%
Red and white equals 50%
Red equals 10%
Know the different types of charges?
Normal , float and boost ( emergency)
What is the proper charge level of a vented and sealed battery
Vented should be at .005 of specific gravity corrected temperature sealed should be an approximate 2.33 volts DC per cell
How often should floating charge batteries be checked
Every 90 days
When does a boost charge need to be applied to vented batteries
If there is more than .010 difference between two cells or there is a drop more than .015
What is the rate of discharge in a battery
One hour equals 55% 2 hr equals 65% three hour equals 75% 6 hr = 90 percent 10 hr = 100 percent
When does a boost charge need to be applied to a sealed battery
If a cell drops below 2.10 V DC
At what temperature should you terminate a charge to a vented battery
125 degrees
If batteries are stored in a cool place around 4°C what can a specific gravity be raised to
1.275 or 1.285 per cell with an average of 1.280
What is the max specific gravity of sulfric acid to be added to a battery
1.350
What is the federal regulation determining the purchase for distilled water for batteries
Oh – B – 41. O- S – 801
What are the three signs of sulfation on a battery
Falling specific gravity, low voltage discharge and loss of capacity
Types of batteries on a 47
Agm gell cells
Liquid electrolyte from a lead acid battery should be neutralised with
Baking soda or alkali
Never allow the battery to stand in a completely discharge condition for more than
24 hours
Always replace batteries in
Sets or pairs at the same time
A routine charge given in accordance with the data on the nameplate during ordinary cycle operation to restore the battery to a substantial fully charged condition
Normal charge
An extended charge given periodically to ensure that all the sulfate is driven from the plates in all the cells are restored to a uniform specific gravity
Boost charge
When putting a boost charge on batteries for at least four hours when and how long do you take readings for
Taking a 30 minute intervals to fully charged
During mixing yes it must be ported to the water and not the water poured into the acid the acid——– to prevent excessive heating and splashing
Must be added slowly and cautiously to the water
What happens when salt water comes in contact with batteries
Chlorine gas is formed
What are the key dividers in the wye connector generators
Voltage per leg of the winding is equal to the line voltage divided by 1.73 phase current is the same as line current
What are the key dividers in delta connected generators
Voltage is the same as line voltage current per leg is equal to line Current divided by 1.73
What is the synchronous speed of a 60 Hz , 4 and six poll generator
3600 and 1800 and 1200 rpm
What is the synchronous speed PDA 400 Hz 2
, 4 and 6 poll generator
24K 12 K and 8K
What type of rotors are most common
DC excited revolving field
