NEETS Module 19

Safety Observations for Electrical and Electronics Technicians

Working safely is the most important thing you can do. Safety must be your primary concern when working with electrical and electronic equipment. Most mishaps or injuries result from not understanding a risk or danger.

Essential Safety Precautions:

• Never work alone on electrical equipment
• Never receive an intentional shock
• Only work on, operate, or adjust equipment if you are authorized
• Don't work on energized equipment unless absolutely necessary
• Keep loose tools, metal parts, and liquids away from electrical equipment
• Never use steel wool or emery cloth on electric and electronic circuits
• Never attempt to repair energized circuits except in an emergency
• Never measure voltage in excess of 300 volts while holding the meter wire or probe
• Use only one hand when operating circuit breakers or switches
• Use proper tag-out procedures for regular and preventive maintenance

Working in Hazardous Environments:

• Be cautious when working in voids or unvented spaces
• Beware the dangers of working aloft
• Never attempt to stop a rotating antenna manually
• Keep protective closures, fuse panels, and circuit breaker boxes closed unless actually working on them
• Never bypass an interlock unless authorized by the commanding officer, and then properly tag the bypass

Reference Materials:

• Electronics Installation and Maintenance Book (EIMB), General, NAVSEA SE000-00-EIM-100, paragraph 3-4
• Naval Electronics Systems Command's Electronic Safety Handbook, E0410-AA-HBK-010/00K ELEXSAFE

First Aid Fundamentals

First aid is the emergency care you give to sick or injured persons. It consists only of providing temporary assistance or treatment until medical help is available. In addition to knowing what to do for a victim, you should also know what not to do.

Three Primary Tasks of First Aid:

1. Maintain breathing
2. Stop bleeding
3. Prevent or reduce shock

Electric Shock

Electric shock may cause anything from mild surprise to death. The effects are often unknown and difficult to determine immediately.

Symptoms of Electric Shock:

• Very white or pale blue skin
• Bluish color to mucous membranes (inside mouth, under eyelid, under nail bed)
• Very weak or absent pulse
• Unconsciousness
• Skin burns
• Possible muscle stiffness (do not confuse with rigor mortis - people have recovered after body stiffness has set in)

Rescue Procedures:

1. Shut off the power immediately
2. If power cannot be shut off, protect yourself with dry insulating material and use a dry board, belt, or clothing to free the victim (DO NOT TOUCH the victim directly)
3. Immediately administer artificial respiration or CPR as necessary
4. Anyone who receives a significant shock should be taken to medical facility and observed for several hours

Artificial Ventilation

A person who has stopped breathing is in immediate critical danger. Life depends on oxygen breathed into the lungs and carried by the blood to every body cell. Since body cells cannot store oxygen and blood can hold only a limited amount, death will result from continued lack of breathing.

Mouth-to-Mouth Ventilation:

1. Clear the victim's mouth of obstructions (false teeth, foreign matter)
2. Place one hand under victim's neck, heel of other hand on forehead
3. Tilt the head back to open the airway
4. Pinch the nostrils shut using thumb and index finger
5. Take a deep breath and cover the victim's mouth with yours
6. Blow into the victim's mouth
7. Remove your mouth to allow victim to exhale
8. Observe chest movement
9. Start with 4 quick ventilations allowing partial inflation only
10. Continue at 12-15 ventilations per minute (one breath every 5 seconds)

Mouth-to-Nose Ventilation:

This method is effective when the victim has extensive facial or dental injuries. The procedure is the same as mouth-to-mouth except you seal the victim's lips and blow into the nose.

Cardiopulmonary Resuscitation (CPR)

CPR must be started within 4 minutes of cardiac arrest to be effective. It consists of external heart compression and artificial ventilation.

One Rescuer CPR Technique:

1. Check for consciousness - try to arouse the victim
2. Check vital signs (breathing, pulse)
3. Establish open airway and ventilate 4 times
4. Check carotid (neck) pulse
5. If no pulse, locate the sternum properly (avoid the lower cartilage tip which can damage the liver)
6. Position hands: heel of one hand on sternum, other hand on top, fingers interlocked and off chest
7. Lean forward with elbows locked, apply vertical pressure
8. Depress sternum 1½ to 2 inches for adults
9. Perform 15 compressions followed by 2 ventilations
10. Continue for 4 full cycles at 60-80 compressions per minute
11. Check pulse and breathing
12. Continue until victim responds or medical personnel arrive

Two Rescuer CPR:

When two trained rescuers are available, use a 5:1 ratio (5 compressions to 1 ventilation). One rescuer performs compressions while the other handles ventilation. The leader makes preliminary checks and coordinates the effort.

Hemorrhage Control

The average adult body contains about 5 quarts of blood. One pint can usually be lost without harmful effect. Loss of 2 pints usually causes shock. If half the blood is lost, death almost always results.

Types of Bleeding:

• Capillary: Brick red color, oozes slowly
• Venous: Dark red, steady even flow
• Arterial: Bright red, spurts with heartbeat (or steady stream if deep)

Methods of Controlling Bleeding:

1. Direct Pressure (First Method):

• Place sterile dressing over wound
• Firmly fasten with bandage
• If bleeding continues, add another dressing over first
• Apply direct hand pressure if needed
• If no material available, use bare hand

2. Pressure Points (Use While Applying Direct Pressure):

• Apply pressure between wound and heart
• Use appropriate pressure point (11 on each side of body)
• Compress artery against bone using fingers or hand
• Can be maintained for about 15 minutes
• Use while assistant bandages wound

3. Tourniquet (Last Resort Only):

• Can only be used on limbs (not head, neck, or trunk)
• Apply above the wound, as close as practicable
• Use flat band (never rope, wire, or narrow cloth)
• Include a pad over the artery
• Tighten only enough to stop bleeding
• Do not cover - mark large "T" on victim's forehead
• Do not loosen except in extreme emergency

Shock

Shock is a condition in which blood circulation is seriously disturbed. All injuries result in some form of shock. Signs may not appear until hours after injury.

Symptoms of Shock:

• Weak and rapid pulse
• Shallow, rapid, and irregular breathing
• Cold, pale skin (or bluish mucous membranes)
• Profuse sweating
• Dilated (enlarged) pupils
• Thirst, weakness, faintness, dizziness
• Nausea, restlessness, anxiety
• Decreasing responsiveness

Prevention and Treatment:

• Begin treatment as soon as possible
• Keep victim lying down
• Raise feet 12 inches higher than head (unless contraindicated by injuries)
• Keep warm for comfort but do not overheat
• Give fluids sparingly if conscious (water, tea, coffee)
• Never give alcohol
• Immobilize fractures
• Remove wet clothing, provide dry covering
• Do not use artificial heat (hot water bottles, etc.)

Burns

Seriousness depends on extent of burned area and depth of burn. Burns involving 15% or more of body cause shock. Burns over 20% endanger life. Burns over 30% are usually fatal without adequate treatment.

Burn Classifications:

• First Degree: Slight pain, redness, tenderness, increased temperature
• Second Degree: Inner skin damaged, blistering, severe pain, dehydration, possible shock
• Third Degree: Skin destroyed, possible tissue/muscle damage, charred or white lifeless appearance, chills, shock will result, pain may be less due to destroyed nerve endings

Burn Treatment:

• Immerse burned area in cold water or apply cold compresses
• Continue until no pain when exposed to air
• Gently pat dry with lint-free cloth
• Cover with cleanest (preferably sterile) dressing available
• Give burn victims large amounts of slightly salted water
• Aspirin for pain relief
• Never apply ointments, butter, lard, petroleum jelly, antiseptics
• Never break blisters or remove tissue or charred clothing
• Never use petrolatum gauze

Heat-Related Illnesses

Heatstroke (LIFE-THREATENING EMERGENCY - 20% Fatality Rate):

Symptoms:

• Body temperature 105°F (41°C) or higher
• Flushed, very dry, very hot skin
• Constricted (pinpoint) pupils
• Fast and strong pulse
• Deep rapid breathing initially, then shallow and almost absent
• May have headache, nausea, dizziness, weakness beforehand

Treatment (Reduce Body Heat Immediately):

• Douse body with cold water or apply wet cold towels
• Move to coolest possible place
• Remove as much clothing as possible
• Maintain open airway
• Place on back with head/shoulders slightly raised
• Apply cold packs under arms, around neck, at ankles, in groin
• Expose to fan or air-conditioner
• Immerse in cold water bath if possible
• Give cool water if conscious (no hot drinks or stimulants)
• Get to medical facility ASAP - continue cooling during transport

Heat Exhaustion (Most Common Heat Condition):

Symptoms:

• Ashen gray appearance
• Cold, moist, clammy skin
• Dilated (enlarged) pupils
• Weak pulse
• Rapid, shallow breathing
• Below normal body temperature
• Weakness, dizziness, headache, loss of appetite, nausea

Treatment:

• Treat as shock
• Loosen clothing
• Apply cool wet cloths
• Move to cool or air-conditioned area
• Fan the victim
• Do not allow to become chilled
• If conscious: give solution of 1 teaspoon salt per quart of cool water
• If vomits, do not give more fluids
• Transport to medical facility ASAP

Introduction to Electrical Formulas

This chapter provides basic electrical formulas used in solving electrical problems. These formulas cover capacitance, current, inductance, power, reactance, impedance, resistance, voltage, and transformers.

Capacitance

Capacitance is the property of an electrical device to store energy in a way that opposes a change in voltage. A capacitor is used to store electrical energy. The FARAD is the basic unit of measurement.

Time Constant (RC Circuit):

The time to charge a capacitor to 63.2% of applied voltage or discharge to 36.8% of initial voltage:

Capacitors in Series:

Capacitors in Parallel:

Current

Current is the directed flow of electrons. It is measured in AMPERES (amps). One amp flows when one coulomb (6.28 × 10¹⁸ electrons) passes a point in one second.

Ohm's Law for Current:

AC Current Formulas:

Inductance

Inductance is the characteristic of an electrical conductor that opposes a change in current. The symbol is L and the basic unit is the HENRY (H).

Mutual Inductance:

Series Inductors (Without Coupling):

Series Inductors (With Coupling):

Parallel Inductors (No Coupling):

Time Constant (RL Circuit):

Inductive Reactance:

Power

Electrical power is the rate at which work is being done, measured in WATTS.

DC Power Formulas:

AC Power:

True Power (Watts):

Reactive Power (VARs):

Apparent Power (VA):

Power Factor:

Reactance

Reactance is the opposition to AC current flow by inductance and capacitance, measured in ohms.

Capacitive Reactance:

Net Reactance:

Impedance

Impedance is the combined opposition to current flow by resistance and reactance, measured in ohms.

Resistance

Resistance is opposition to current flow, measured in ohms (Ω).

Ohm's Law:

Series Resistance:

Parallel Resistance:

Voltage

Voltage is the electrical potential energy between two points, measured in volts.

Ohm's Law:

Voltage Divider:

Transformers

A transformer transfers electrical energy from one circuit to another by electromagnetic induction.

Turns Ratio:

Voltage Ratio:

Current Ratio:

Power Relationship:

Introduction to Electronics Formulas

This chapter provides basic electronics formulas for antennas, resonance, transistors, vacuum tubes, wavelength, and radar applications.

Antennas

An antenna is a conductor or group of conductors used for radiating or collecting electromagnetic energy from space.

Antenna Gain:

Antenna gain (G) describes the effectiveness of a directional antenna compared to a standard reference antenna. The gain is the same whether transmitting or receiving.

Effective Radiated Power (ERP):

Half-Wave Dipole Length:

Quarter-Wave Antenna Length:

Antenna Efficiency:

Resonance

Resonance exists when inductance, capacitance, and applied frequency are such that inductive reactance and capacitive reactance cancel each other (X_L = X_C).

Resonant Frequency:

Quality Factor (Q):

Bandwidth:

Transistors

Transistors are semiconductor devices with three or more elements. The term derives from "TRANSfer resISTOR," describing the transfer of input signal current from low-resistance to high-resistance circuit.

Current Relationships:

Alpha (α) - Common Base Configuration:

Beta (β) - Common Emitter Configuration:

Relationship Between Alpha and Beta:

Transistor Power:

Vacuum Tubes

Vacuum tube characteristics are measured by amplification factor (μ) and transconductance (g_m).

Amplification Factor (μ):

Transconductance (g_m):

Plate Resistance (r_p):

Relationship:

Wavelength and Frequency

Wavelength is the distance in space occupied by one cycle of a radio wave. It varies from fractions of an inch at high frequencies to many miles at extremely low frequencies.

Wavelength Formula:

Frequency Formula:

Period:

Velocity:

Radar Formulas

Radar systems use electromagnetic waves to detect and locate objects.

Key Terms:

• PW (Pulse Width): Width of transmitted RF pulse
• PRT (Pulse Repetition Time): Time between pulses (leading edge to leading edge)
• PRF (Pulse Repetition Frequency): Number of pulses per second = 1/PRT
• Duty Cycle: Ratio of pulse time to total time
• P_pk (Peak Power): Actual power during pulse (kilowatts)
• P_avg (Average Power): Power averaged over one PRT (watts)

Pulse Repetition Frequency:

Duty Cycle:

Average Power:

Peak Power:

Maximum Radar Range:

Minimum Radar Range:

Range Resolution:

Decibels (dB)

Decibels represent a logarithmic comparison between two signals, usually output and input. In power measurements, 0 dBm equals 1 milliwatt.

Power Ratio in dB:

Voltage/Current Ratio in dB (Equal Impedances):

dBm (Reference to 1 mW):

Quick Reference:

dB	Power Ratio	Voltage Ratio
0	1	1
3	2	1.41
6	4	2
10	10	3.16
20	100	10
-3	0.5	0.707
-10	0.1	0.316

Introduction to Reference Data

This chapter provides essential reference data tables and identification systems used by electronics technicians. This information is critical for proper component selection, identification, and circuit troubleshooting.

Capacitor Identification

Two methods are used for capacitor identification: typographical marking (printed numbers) and color code marking (becoming obsolete).

Typographical Identification:

Part numbers are printed on the capacitor body. Different capacitor styles use different formats:

• CB Style: Uses specific part number format from MIL-C-10950
• CMR Style: Uses format from MIL-C-39001 (mica, silvered)
• CYR10 Style: Cross-referenced in MIL-C-23269/1

Important Capacitor Specifications:

Style	Description	Status
CCR	Ceramic, Encap., Temp. Comp., ER	Active
CMR	Mica, Silvered, ER	Active
CWR	Tantalum, Solid, Chip, ER	Active
CYR	Glass, Non-ER	Active
RLR	Film (Insulated), ER	Active

Note: ER = Extended Reliability

Common Dielectric Constants:

Material	Constant
Vacuum	1.0000
Air	1.0006
Paraffin paper	3.5
Mica	3 to 6
Glass	5 to 10
Rubber	2.5 to 35

Resistor Identification

Resistors use color code bands or printed values for identification.

Resistor Color Code:

Color	Digit	Multiplier	Tolerance
Black	0	×1	-
Brown	1	×10	±1%
Red	2	×100	±2%
Orange	3	×1K	-
Yellow	4	×10K	-
Green	5	×100K	±0.5%
Blue	6	×1M	±0.25%
Violet	7	×10M	±0.1%
Gray	8	×100M	±0.05%
White	9	-	-
Gold	-	×0.1	±5%
Silver	-	×0.01	±10%

Standard Resistor Selection:

Type	Style	Power	Tolerance	Ohmic Range
Composition ER	RCR20	0.5W	5%, 10%	1.0Ω to 22MΩ
Composition ER	RCR32	1W	5%, 10%	1.0Ω to 22MΩ
Film ER	RNR55	0.1W	1%, 0.5%, 0.1%	10Ω to 2MΩ
Film ER	RNR70	0.25W	1%, 0.5%, 0.1%	1.0Ω to 4.02MΩ

Transformer Lead Identification

Transformers use standard color codes for lead identification:

Power Transformers:

• Black: Primary leads (line connections)
• Black/Yellow: Tap on primary (if used)
• Red: High voltage secondary (B+ winding)
• Red/Yellow: High voltage center tap
• Green: Low voltage winding (heater, filament)
• Green/Yellow: Low voltage center tap
• Brown: Additional windings

IF and Interstage Transformers:

• Blue: Primary end (plate or collector)
• Red: B+ or V_CC connection
• Green: Grid or base connection
• Black: Ground or common

Chassis Wiring Color Standards

Standard wire colors for circuit identification:

Circuit Function	Color
Grounds, Grounded Elements, Returns	BLACK
Heaters/Filaments, Off Ground	BROWN
Power Supply +VCC/+Ebb	RED
Screen Grids	ORANGE
Emitters/Cathodes	YELLOW
Bases/Control Grids	GREEN
Collectors/Plates	BLUE
Power Supply -VCC/-Ebb	VIOLET
AC Power Lines	GRAY
Miscellaneous, AVC	WHITE

Semiconductor Identification

Diode Markings:

Diodes use a band or color code to indicate the cathode (negative) end. The band is usually near the cathode end of the body.

Transistor Lead Identification:

Transistor pinouts vary by package type:

• TO-92 Package (common plastic): Looking at flat face - typically E-B-C from left to right
• TO-220 Package (power): Tab is usually collector, leads are B-C-E or E-C-B
• TO-3 Package (large power): Case is collector, two pins are base and emitter

Integrated Circuit (IC) Pin Numbering:

• DIP (Dual In-line Package): Pin 1 indicated by dot or notch, count counterclockwise
• Pin 1 is top-left when notch is at top
• Pins numbered sequentially down left side, then up right side

Battery Types and Specifications

Primary Cells (Non-Rechargeable):

Common sizes for flashlights and portable equipment:

Size	Part Number	Voltage
AA	BA58	1.5V
C	BA42	1.5V
D	BA30	1.5V
9V	BA484	9V

Secondary Cells (Rechargeable):

Used in vehicles and rechargeable equipment. Examples include lead-acid, NiCd, NiMH, and Li-ion batteries.

Cable Types and Applications

Common Shipboard Cable Types:

Type	Description	Application
DSS	Double conductor, shielded	Signal/audio
THOF	Three conductor, oil resistant	Power, flexible service
TSP	Twisted pairs	Telephone, data
MWF	Multiple conductor	Outboard submersible
CVSF	400-Hz aircraft servicing	Aircraft power

Current-Carrying Capacity (30°C Ambient):

Wire Size	Rubber Insulated (A)	Heat Resistant (A)
#14 AWG	20	30
#12 AWG	25	40
#10 AWG	40	55
#8 AWG	55	70
#6 AWG	80	100
#4 AWG	105	135

Reference Material Sources

Additional technical information can be found in:

• MIL-STD-198E: Capacitors, Selection and Use of
• MIL-STD-199C: Resistors, Selection and Use of
• NAVSUP Pub 4400: Afloat Shopping Guide
• MIL-W-76B: Equipment Hook-up Wire Specification
• NAVSEA 0902-LP-006-0000: Design Data Book
• NAVSEA SE000-00-EIM-100: Electronics Installation and Maintenance Book