1. Electrical Fundamentals
Introduce yourself, sell the topic, establish credibility, discern knowledge level of the class.

2. Board of INSURV on USS Trenton “First Electrified Naval Ship”
Electricity, First Installation on a US Navy Ship, USS Trenton
The first installation of electric lights in a US Navy warship took place during the summer of Earlier that spring, seven electric power companies were asked by the Bureau of Navigation to submit bids for installing lights in USS Trenton, then currently berthed at the New York Navy Yard in Brooklyn. Only one, the Edison Company for Isolated Lighting, submitted a bid of $5,500 to install one L dynamo & one Armington-Sims engine complete to supply light via insulated wiring to candle power lamps, candle power lamps, and 4 32-candle power lamps. The ensuing contract also included 238 key sockets, 6 extra brushes, 1 automatic regulator and 1 dynamo foundation. Lieutenant.Commander. R. B. Bradford, executive officer of the ship, oversaw the installation of this equipment in Trenton between 7 June and 21 August Owing to the need to maintain the engine and dynamo, the system was only run at night. Other than minor wiring problems, the initial trial during Trenton's service on the Asiatic Station was a success and in 1884 the Bureau of Navigation decided to light Atlanta, Boston and Omaha. The plant for these ships were supplied, respectively, by the U.S. Electric Lighting Company of New York, the Brush Electric Company of Cleveland, and the Consolidated Electric Light Company of New York. In 1886, the Bureau of Navigation reported that "[t]his method of lighting ships of war, owing to the small amount of heat given off, the absence of disagreeable odors, and the more perfect illumination, adds much to the health and comfort of the officers and men, tends to make them contented and happy during their long absences from home and friends, promotes discipline and prevents crime."
Pictured above is the Board of Inspection and Survey circa 1887.

3. REFERENCES NSTM 300 ELECTRIC PLANT GENERAL
NAVEDTRA ELECTRICIANS MATE
NSTM 310 GENERATORS/ CONVERSION EQUIP
NSTM 320 DISTRIBUTION SYSTEMS
NEETS MOD INTRO TO DIRECT CURRENT
NEETS MOD INTRO TO AC CIRCUITS
Stress NSTM 300, revision 7 (June 2005). EVERYONE should be familiar with reference and keep a copy handy.

4. TERMINAL OBJECTIVE
DESCRIBE and EXPLAIN the function and theory of shipboard electricity and its role in the electrical distribution system.
Self explanatory

5. ENABLING OBJECTIVES
State the basic units of measure, symbols or abbreviations for various electrical terms.
Define Ohm’s law
State the three requirements for electromagnetic induction
Define the types of AC power
Describe the internal parts of a generator
Self Explanatory

6. More Objectives
State the functions of a governor and a voltage regulator
Explain the theory of operation of transformer action
Explain a real ungrounded electrical system
Describe Selective and Selected Tripping
Self Explanatory

7. Starring The “ATOM”
More electrons on outer shell: more of a conductor (gold, platinum, copper, silver)
Less outer shell electrons (more protons): more of an insulator (plastic, rubber, wood)
A few more outer shell electrons than protons: Semiconductors (germanium, silicon)

8. VOLTAGE – “Electrical Pressure”
3 Factors necessary to produce an AC Voltage
Conductor
Magnetic Field
Relative motion between the two
Describe the construction of a basic generator and the relative location of the three elements with regards to a turbine generator.
Conductor = Stator windings.
Magnetic Field = Rotor
Relative motion provided by turbine connected to rotor shaft.

9. Current - What is it? Voltage and Complete Path Needed
Movement of Electrons Past a Given Point (Measured in AMPS)
1 “Coulomb” in 1 sec. past a given point = 1 AMP
Coulomb= 6.28 x 1018 electrons
Current is the flow of electrons from source to load based on the Difference in Potential between the Source and the Load. Flows only in a complete path.
The symbol “I” comes from the German word “Intensitat” meaning Intensity.
Heat and a magnetic field are by-products of current.

10. “RESPECT…NOT FEAR” .001 Amps = “Tingling Sensation” (Shock Felt)
.01 Amps = “Clutching Current”
.1 Amps = May be Fatal
Deaths as low as 30V have been documented
Info per NSTM 300/ OPNAV D

11. OHM’s LAW E=IR Voltage = Current * Resistance I=E/R R=E/I or
Discuss the use of Ohm’s Law. Ohm’s law is good for a gross representation of Distribution System operation. Can be solved for Voltage, Current or Resistance. Does not take into account the change in phase angle inherent in AC distribution systems. However, can be used to give a rough determination of proper operation. It is very useful for talking about theory of operation. Typical body resistance 1200 Ohms.
I=E/R R=E/I 12 12 12

12. In SERIES…the Law Is: Current (I) is COMMON throughout
Resistance (R) is ADDITIVE
Voltage (E) is ADDITIVE
Used rarely, but fundamental to learning about Ohm’s Law.

13. The Basic SERIES Circuit
Compare to analogy of automobile. What would happen if your car was wired in series and one of your loads burned up?

14. In PARALLEL, the Laws are Different:
VOLTAGE (E) is COMMON in every branch
CURRENT (I) is Additive
The TOTAL circuit RESISTANCE (R) is LESS than any one Branch!
Parallel is most common type of circuit. Current is increased as loads are added, but total resistance goes down. Inversely proportional

15. How much total Current? How much total Resistance?
Have students do calculations: Ir1= 2A, Ir2=5A, It= 100/7= 14.3A (roughly).
Stress how overall resistance ended up being less than the smallest branch.
Current and Total resistance are inversely proportional, therefore, when loads are started on the ship in Parallel, current on the bus goes UP.

16. “Shorts & Opens” Electrical “SHORT” = Minimal Resistance
Electrical “OPEN” = Infinite Resistance
Shorts cause loads (machinery) not to work, but amperage can be extremely high and dangerous.
Fireman going on liberty on Friday afternoon: hit the brow? Or, ask permission from entire chain? Path of Least Resistance, just like current.

17. INDUCTANCE AND CAPACITANCE
INDUCTOR: Opposes CHANGE in CURRENT
(Measured in “Henry’s”)
CAPACITOR: Opposes CHANGE in VOLTAGE
(Measured in “Farads”)
The COMBINED Opposition is called “Reactance” and measured in OHMS
Inductor: emphasize “CHANGE” in current opposition. Expanding and Contracting magnetic field. May “induce” into external windings. EVERY conductor has inductance. Small power losses occur when magnetic field is transferred (Copper losses)
-Looped windings produce more inductance and a “counter electro-motive force” (will talk more about it when we discuss “armature reaction” later.) STORES energy in an “electro-magnetic” field.
CAPACITOR: STORES energy in an “electro-static field”. Made up of two plates separated by dielectric.
Reactive power are LOSSES in the overall system

18. INDUCTOR
Every wire is an inductor.

19. Current “Limiter” in circuit
Uses of an inductor…provide a “slow buildup” of voltage to a load.

20. INDUCTOR: “Friend” or “Foe?”
  This large voltage spike when current is interrupted through a coil is called "inductive kick." Inductive kick is the major contributor to the erosion of the contacts in our switches and circuit breakers.  The damage is usually referred to as pitting.  In our circuit breakers we use arc chute assemblies to dissipate the arc produced when the breaker opens.  Without arc chutes, the arc would be an uncontrolled fire ball.
Inductive kick is the unintentional injection of energy into a circuit from the collapsing of the magnetic field in an inductor when its source of power is disconnected.
Analogy of :surge protectors” for home/ computer use.

21. CAPACITOR
Simply stated, a capacitor is two conducting surfaces separated by a dielectric (insulating) material. Examples of dielectric materials are air, paper, wood, and rubber. The two plates are physically separated from one another and current cannot flow across the dielectric.
A capacitor is used to store a charge by creating a voltage across the two conducting plates.  A capacitor which is charged to a potential of one volt and carries a charge of one coulomb is said to have a capacitance of one farad.

22. Theory of Operation
After a certain period of time, the capacitor voltage will be equal in magnitude to the source voltage (Vc = E) and current will cease to flow (Figure -14).  At this point, the capacitor is completely charged and current is zero.  As you can see, voltage cannot change instantaneously across a capacitor, just as current cannot change instantaneously through an inductor.
What happens when the switch is Opened?
Caps retain their charge until they have a “discharge path”

23. Nothin’ To Play With!
We have all used cameras with a built-in flash.  Have you ever wondered how the flash works?  Well, when the flash is turned on, a capacitor charges up.  This is that humming sound you hear.  When you push the button to take the picture, the capacitor is connected to the flashbulb circuit and discharges its stored energy through the flashbulb. The capacitor will remain uncharged until the next time the flash is turned on.

24. Use a Shorting Probe…Not your Fingers, Stupid!
Precautions
Equipment that contain capacitors can be dangerous long after it has been secured due to the stored charge across the plates.  Remember that the capacitor charge equals the source voltage.  Some electronic equipment operate at up to 20,000 Volts.  If a person were to touch a charged capacitor, the stored energy would discharge through the person's fingers and cause an electrical shock (Figure -16).  This is why shorting probes are used inside electronic gear before troubleshooting.  

25. So what are they good for?
A standard “EMI” filter network for protecting electronics from “Inductive Kick.”
-When switch is opened, magnetic field collapses and charges capacitor instead of “frying” switch contacts. When magnetic field collapses enough, cap discharges back into inductor. This goes back and forth until enough power is dissipated between the two to take voltage to a minimum.

26. POWER Power = Current x Voltage “RATE at which work is being done”
(Measured in WATTS)
FYI: 1 Horse Power = 746 Watts
Use 500 LB barbell analogy. Can you lift those weights and place them on the bench all at once? Or, can you do it a couple of weights at a time? You used the same amount of power, but took more time to consume it. Another analogy: 100 Watt generator powering your kitchen: 60 Watt toaster, 75 watt Microwave. Can you run them both at the same time? Separately? More time needed due to capacity.

27. POWER (Cont) True - Power that actually does work. (KW Meter)
Reactive - Power used by reactive elements.
(KVAR - not useful)
Apparent = combination of Ptrue and Preactive Power.
True power is called Real Power and consists of the KW load that actually performs work in the form of pumps pumping, and fans blowing. TP=AP-RP
Reactive Power - Consists of current losses as heat due to inductive and capacitive elements trading currents as they perform their functions of opposing current and voltage changes respectively.
Apparent Power – Ideal system comparison that does not take reactive elements into account

28. Power Factor (PF)
Ratio of TRUE Power (Wattmeter), to APPARENT Power (KVA: Ammeter x Voltmeter).
.8 PF is Standard on Naval Ships
Identifies Power Lost due to Reactive Elements
TP = KW = POWER FACTOR
AP KVA
Standard is .8 PF but will vary due to amount of inductors and capacitors added.

29. Leading or Lagging?
Current LAGS Voltage in predominantly “Inductive Circuits”
Current LEADS Voltage in “Capacitive Circuits”
Ships have more cabling (wires) than capacitors and therefore: have a LAGGING Power factor.
ELI the ICE man.

30. “ELI the ICE Man”
Amplifies previous slide. CONSIDER A BREAK AT THIS POINT.

31. The World of Electromagnetic Induction: AC baby!
At point A on the curve in Figure 3 there is no relative motion between the rotor field and the stator windings.  This makes the induced voltage zero.  As the rotor field moves down and toward the stator windings, it "cuts" more and more conductors. The induced voltage gradually increases and reaches a peak at point B.  As the rotor field continues down to the bottom, it cuts fewer and fewer conductors. The induced voltage gradually decreases and reaches zero again at point C.
As the rotor field moves up through and back into the stator windings, it cuts more and more conductors again and the induced voltage gradually increases and reaches another peak at point D (Figure 3).  The polarity (+,-) of the induced voltage reverses because the rotor field is passing back into the stator. The potential reaches a negative peak at point D.  As the rotor field continues up past the stator windings, it cuts fewer and fewer conductors. The induced voltage decreases until it returns to zero at point A and one cycle has been completed.
When the rotor field passes through one revolution on a two pole (N,S) generator, one cycle of AC voltage is produced.  This relationship is very important in the design of generators. 

32. Single Phase Alternating Voltage
Frequency = Cycles/sec = Hertz (Hz)
One Cycle
Voltage
Discuss the cycle. Discuss Electrical sine wave and the meaning of cycle. As seen on an oscilliscope. Amplitude of wave demonstrates voltage. Can be varied with field strength of rotor.
Time 4

33. Frequency Calculation
Dependant on number of “POLES”, and SPEED of the rotor (prime mover RPM)
F = n x s
120
F= Frequency N = Number of Poles
S= Speed (RPM) of Rotor
120 = standard formula constant
Frequency can only be changed by varying the number of “poles” or changing the RPM of the prime mover.
If OPS wants his fan to run faster, we’ll have to run the ship at 70 hertz.

34. I need more Power Scotty!
Three-phase machines (both generators and motors) have several advantages over single-phase machines.  Three-phase machines make more efficient use of materials and therefore are not as expensive as single-phase equipment of the same rating.  
In the top drawing of Figure 4, you see that much of the space within a single phase generator is wasted.  In the case of three-phase motors, operating cost is less, they are easier to start, and they run with less vibration.  (A three-phase source provides more of a rotational effect since the each phase peaks sequentially; a single-phase source provides more of a simple on/off effect.)
Show Slide on generation (movie graphic)

35. Talk about Magnetic Induction… By design of the rotor and stator constructions, 60 Hertz/ 450 Volt AC is produced. How many AMPS is decided by insulation resistance as CURRENT = HEAT.
Mention “Armature Reaction” and reference inductors/ power losses. Collapsing field intensity dependant on current produced. Whatever load demands for current, the greater the armature reaction and distortion of the electrical neutral plane between rotor and stator. Minimal, but does account for power losses.
Why a rotating field/ stationary armature instead of vice versa? More Cost effective and smaller construction overall.

36. Maintenance issues: WEAKEST part of generator
Sliprings, carbon brushes, spring tension, DC INPUT to rings, swap F1 and F2

37. Armature Reaction: Can’t Stop It
The magnetism induced into the stator opposes the field that created it. This creates a Counter EMF (counter-torque) if you will. This actually causes the generator to slow a bit and the resultant effect is that the rotor field is weakened and distorted resulting in a lesser amount of current flowing for the demand of the load.
When voltage regulators are discussed later, we will show how this is compensated for.

38. Ship’s Service Switchboards
Number and location varies from ship to ship, usually two or more
Placed as far apart as feasible
Briefly mention switchboards…tell students they will get ship specific in Specialty portion of course. The following two slides are pictures of a SWBD and an EPCC. 9 9 9 8 9 9 9 9 9 9 9 9 9 9 9 9 9

39. Switchboard

40. EPCP operation Remote operations Allows the operator:
Start and stop generators
Monitor electrical plant
Parallel generators
In addition, the console monitors parameters & control of the bus tie breakers.
Shore power is also monitored from the console. 2

41. Ground Detector Lights
Indicates presence of a low insulation resistance
Three lamps and test switch
Normally illuminated
Faulty phase will be indicated by a dark lamp when in test position
Where are the detectors located? Switchboards, lighting panels, and power panels.
How do you isolate grounds? Three methods. Opening bus tie breakers, opening load breakers, and shifting equipment that is in operation.
When opening load breakers, start with non-vital loads and continue with vitals. 7 7 7 42 48 43 7 7 7 7 7 7 7 7 7 7 7

42. “A” Phase Ground Indication
THIS IS AN INDICATION OF AN A PHASE GROUND

43. Ground Detector Operation
Only works when the test button is pushed
Must see lights flicker when pressing test button
Grounds don’t go through transformers
Light must be “out”
If switch not pressed, all lights stay on as there is a complete path from one phase to another through all three lighting transformers.

44. Without a Ground
By pressing switch, we effectively place a ground on one side of each transformer and approximately 277 volts on the other side. The difference in voltages between this state and the previous state (button not pressed = 450 V across transformer), is evidenced by light flicker when button in pressed.

45. With a Ground
If a ground exists on any given phase, then there is no difference of potential on each side of the transformer (ground on each side) on that phase…light goes out.

46. Isolating a Ground WATCH STANDER’S ACTIONS:
OBTAIN PERMISSION FROM EOOW (via CHENG, via CO)
SPLIT ELECTRICAL BUS TO ISOLATE SWITCHBOARD TO LOCALIZE GROUND
RE-PARALLEL ELECTRICAL BUS
SECURE BREAKERS ON AFFECTED SWITCHBOARD ONE AT A TIME UNTIL GROUND GOES AWAY
NON-VITALS FIRST
LIKELY DEVICES - GALLEY EQUIPMENT, EQUIPMENT THAT WAS RECENTLY PLACED ONLINE
There will be a local procedure in the EOOW log/Cheng’s standing orders. More later in Specialty portion of course, and specifically on the electrical trainers in a lab environment..

47. TRANSFORMERS
Common throughout ship. No perfect transformers, always losses in form of heat. Frequency is unchanged but voltage can be manipulated.

48. Transformer Theory
Transfers AC Power from one circuit to another by Electromagnetic Induction
FREQUENCY is not changed
No Moving Parts
Pass around transformer prop.

49. XFMR Construction Consist of PRIMARY and SECONDARY Windings
May be “Step-Up” or “Step-Down”
Determined by “Turns ratio” of Primary and Secondary Windings
Amplifies previous slides

50. GROUNDS ON 115V SYSTEM
If a ground occurs on the secondary side of a transformer, it will not be reflected on the 440 bus

51. Grounds can not be read across transformer cores
Grounds can not be read across transformer cores. Therefore, if ground on 115 Volt side, will not be seen on main switchboard (450 Volt side).
Discuss use of isolation transformers as applicable to NSTM 300.

52. Selective Tripping Designed into the system
Protective device closest to a fault trips
Protects the rest of the system
AUTOMATIC feature inherent to shipboard distribution systems. The protective device closest to the fault trips first.
Fault
Source
SWBD
Ld Ctr
Distr Pnl
15A
100A
750A
4000A
Trips th rd nd st 40

53. Selective Tripping Source Level 1600 A Switchboard Level 250 A
Load Center
Level
Customer
Fused Loads
100 A
250 A
1600 A A
Breakdown of distribution system from generator to customer level. Common sense: problem should lie near where protective device opened. 41

54. SELECTED TRIPPING Is manually controlled by the operator.
This form of isolation is usually reserved
for ground isolation or equipment trouble-
shooting. Normally supervised by the
EOOW.
“Ted” The Operator. MANUAL operation. Talk about proper ways to hunt grounds: common sense areas, communication issues, notifications, expediency in attacking the ground. 42

55. What IS a Real Ungrounded System?
No Ground Conductors
No Neutrals
All “Hots”
In THEORY, one could touch a live conductor and not get shocked, since there is no return path for current….but JUST in THEORY!
Current needs a return path to be viable. In theory, there is no return path. See next slide.

56. ONLY in theory!

57. Mention inherent or effective capacitance and use ship as an example (cables= negatively charged plate/ air= dielectric/ hull= positively charged plate). Also, many resistive and inductive paths to ground.

58. ANY QUESTIONS?
Address any questions. 54

59. ?????????? What are the 3 requirements for Electro-Magnetic Induction?
What is OHMS Law? What is the “Power Formula?”
What is “Power Factor?”
Conductor, Magnetic Field and Relative Motion
2. I=E/R P=IE
3. Ratio of True Power(KW) to Apparent Power (KVA) or KW/KVA

60. More of the Same…. What is Inductance and Capacitance?
What tool do we use to discharge a Capacitor?
What is the frequency formula?
Inductance: Opposes a CHANGE in current (henries)
Capacitance: Opposes a CHANGE in voltage (farads)
Shorting Probe
F=#poles x speed of rotor / 120 constant)

61. And Lastly… What is selective tripping?
What is armature reaction and how does our generation system compensate for it?
What is effective capacitance?
Automatic feature where protective device closest to fault trips first.
2. Increased current (due to increased load) felt at rotor. Initially slows rotor (compensated for by governor) and distorts or weakens magnetic field around rotor (compensated for by voltage regulator).
3. Ship acts as a huge capacitor (cabling is negative plate/ air is dielectric/ hull is positive plate). Defeats the myth that a real ungrounded system is safe (hidden paths to ground).

62. Electrical Fundamentals Review55