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200 Cards in this Set

  • Front
  • Back
The ground system for any facility consists of four basic ground subsystems what are they?
· Earth Electrode
· Lightning Protection
· Fault Protection
· Signal Reference.
Installed properly ground systems provide what?
· Personnel safety
· Protection to electronic communications equipment
· Signal noise reduction.
Ground systems require _____ in order to achieve peak performance
periodic maintenance
The military standard for grounding, bonding, and shielding is what?
MIL-STD-188-124B
Most facilities use a power transformer which supplys ______ secondary output power.
three-phase
Who is responsible for the proper maintenance of a shore station facility, and may be required to identify and inspect a facility’s power and ground system.
Supervisor’s along with maintenance personnel
The horsepower and kilovolt-amp rating delivered by three phase power is _____ greater than with single-phase.
1.5 times
Transformers delivering three-phase power are arranged in the ____ or the ____ configuration.
Star (Wye), Delta
The voltage reading across any two lines of a three-phase Wye connection is equal to the ________
phase voltage times 1.73

E line = 1.73 X E phase
The line current is the _____ as the phase current in a Wye connection.
same because Current in a series circuit is the same throughout all parts.
What is another name for a Star transformer connection?
Wye or Y
A _________ secondary connection will produce line current that is 1.73 times the phase current.
Delta
Before closing a Delta connection, connecting a voltmeter across the three windings will read ______ volts when the windings are properly arranged.
zero
When discussing a facility’s power connection, what is meant by an orange finish?
In a delta connection, one phase conductor has a higher voltage to ground than the other two. This is also known as the high leg and the wire carrying the higher potential is identified with an orange wire.
A Y-Y connection with a 10:1 turns ratio has a line input voltage of 25 volts. What is the voltage across the secondary phase windings?
1.44 volts; 25/1.73 gives the primary phase voltage of 14.4 volts, because the turns ratio is 10:1 the voltage is stepped down to 1.44 volts
In an emergency, a closed delta connection can be converted to an _________ __________ connection.
Open Delta
The Earth Electrode Subsystem consists of a network of buried conductors, such as what?
Rods, wires, pipes, and other configurations of metals designed to provide a low impedance connection to earth.
Ideally, the earth connection would be an impedance of what?
zero ohms
For communications electronics facilities (C-E), a maximum of ___ ohms * has been established as per MILSTD-188-124B.
10
For most non-electronic facilities, an impedance of
___ ohms is acceptable.
25
What are the three subsystems of the Earth Electrode Subsystem?
Lightning protection
Fault protection
Signal ground
What can be added to make the soil more conductive.
Salt
The only way to accurately determine the soil resistivity is to do what?
Measure it
Earth electrode subsystems can be divided into two general types. What are they?
Ring grounds and Radial grounds.
What is the most preferable general type of earth electrode subsystem?
ring ground with 10 ft. minimum ground rods every 15 ft.
What is the typical size of a earth ground rod?
Vertically driven, minimum 10-ft length, ¾- inch diameter, Copper-clad steel
Buried Horizontal Conductors are buried ___ to ___ inches deep
18 to 36
Copper cables buried about
6 inches in the ground
forming a network of
squares which provide
“equipotential” or equal
voltage areas throughout
the facility is refered to as a what?
Grid
The use of water pipes as the sole means of providing an earth electrode subsystem has been ______ by the National Electric Code
banned
As per MIL-STD 188-124B, all driven electrodes used in the Coast Guard must be at least what size?
10-ft. in length and ¾-inch in diameter.
Increasing the size of the electrode from 8 ft to 16 ft will do what to resistance?
reduce the resistance (Rr) from 79.8 to 44.4 ohms.
As stated earlier, the best type of earth electrode subsystem consist of a combination of ________ interconnected by bonded cables.
multiple driven electrodes
When installing multiple driven electrodes, they should be spaced that their spheres of influence ______, but don’t ______ . This is to ensure complete coverage without saturation.
make contact, overlap
The electrode spacing should be _______ of one electrode.
twice the length
The electrode spacing should be _______ of one electrode.
twice the length
What are the six different principal types of Earth Electrode systems?
Ring Ground
Horizontal Bare Wires (Radials)
Horizontal Grid (Bare Wire)
Vertical Rods
Plates
Incidental Electrodes
Which earth electrode system is the easiest to install?
Vertical Rods
What Factors Affect Self Inductance?
· The longer the conductor, the greater the inductance.
· The thinner the conductor, the greater the inductance.
· The more bends in the conductor, the greater the inductance.
What doesTransient surge impedance refers to?
The dynamic (changing) impedance offered by a conductor when a sudden surge of current flows through it.
What is step voltage?
It is the voltage level between the feet of a person standing or walking on the surface.
There are two methods available for testing the resistance to ground provided by the earth electrode subsystem they are?
· Triangulation
· Fall of Potential (three terminal).
The Triangulation method is most effective for measuring ______ systems and is not recommended for ______.
single rod ground, multi-rod configurations.
The most common method for testing the resistance to ground provided by the earth electrod subsystem is?
Fall-of-Potential
What are the two was to enhance the earth electrode subsystem by decreasing soil resistivity?
· Water Retention
· Chemical Salting
A mixture of 75 % ____, 20 % _____, and 5 % _____ provides an effective backfill around ground rods and is superior to the use of bentonite alone.
gypsum, bentonite clay, sodium sulfate
what are the most commonly used chemicals that are used in the chemical enhancement of soil for the earth electrode system?
· Magnesium sulfate (MgSO4)- Epson salts
· Copper sulfate (CuSO4)- blue vitrol
· Calcium chloride (CaCl2)
· Sodium chloride (NaCl2)- common salt
· Potassium nitrate (KNO3)- saltpeter.
The use of chemicals to reduce soil resistivity should be considered only as a _____.
last resort.
What is the simplest method for treating the soil around a vertical ground electrode.
Trenching
What is the maximum resistance to ground for an earth electrode subsystem in a non-communications electronics facility?
25 ohms
Name three types of earth electrode configurations that provide a lower resistance than with a single driven electrode.
Grid, Ring, Buried horizontal conductors.
Should underground water pipes be bonded to an earth electrode subsystem?
Explain Answer.
Yes, at the nearest point of entrance to a facility.
What is the ideal ground rod spacing when connecting multiple electrodes in an earth electrode subsystem?
2 Xs the length of one electrode.
What has a more significant effect in reducing the overall resistance to ground provided by driven electrodes, rod length or rod diameter?
length
Define Air Terminal
The lightning rod or conductor placed on or above a building, structure, tower, or external conductors for the purpose of intercepting lightning.
Define Down Conductor
The conductor connecting the air terminal or overhead ground wire to the earth electrode subsystem.
Define Cone of Protection or Zone of Protection
That’s the space below and adjacent to a lightning protection subsystem that is substantially immune to direct lightning discharges.
The Military Handbook for Grounding, Bonding, and Shielding for Electronic Equipment and Facilities is?
MIL-HDBK-419A
The degree to which a structure is susceptible to lightning will depend on:
· Flash density
· Attractive area
The fact that taller structures attract lightning to themselves actually serves to protect surrounding structures. This protection is known as the?
“zone of protection” or the “cone of protection.”
With respect to the cone of protection a ____ ration is recommend for critical structures.
1:1
What is the acceptible ratio for the cone of protection for ordinary structures?
2:1
What are the five effects caused by lightning strikes?
Thermal Effects
Mechanical Effects
Electrical Effects
Conductor Impedance Effects
Induced Voltage Effects
To protect any structure, such as a building, mast, etc., from lightning damage, what basic requirements must be met?
· An air terminal must be installed.
· A low impedance path from the air terminal to earth must be provided.
· The resistance of the connection between the discharge path and the earth must be low.
What is the lightning protection code issued by the National Fire Prevention Association?
NFPA No. 780
The tip of the air terminal should be at least _____ above the structure you are protecting.
10 inches
For down conductors up to 75 ft the maximum DC resistance shall not be greater than?
0.176 ohm per 1000 ft.
For down conductors of more than 75 ft the max DC resistance shall not be greater than?
0.088 ohms per 1000 ft.
For down conductors the size of wire shall not be less than?
No. 14 AWG, The use of No. 6 AWG copper wire is recommended.
Bending of the down conductor should be gradual and the bend radius should not be less than ____ inches.
8
The angle of any bend for down conductors shall not be less than _____ ?
90 degrees
The average distance between
down conductors shall not exceed _____?
100 ft.
An air terminal must have at least how many paths for discharging the lighting to ground?
two
Ground rods make up the final element of the _____ subsystem.
lightning protection
Ground rods are constructed of what material?
copper-clad steel, solid copper, hot dipped galvanized steel, or stainless steel.
To prevent galvanic corrosion, all ground rods should be constructed of ______. This includes the earth electrode subsystem ground rods.
the same materials.
The ground rod shall be at least __ ft. long and __ inch in
diameter.
8ft, 1/2 inch
Each down conductor shall be terminated by a ground rod dedicated exclusively for ______.
lightning protection.
When dealing with Lightning protection subsytems major deficiencies should be documented in what?
Major Discrepancy Report
Types of major deficiencies include what for lightning protection subsystems?
· Earth electrode resistance too high
· Parts of structure outside the cone of protection
· Other similar types of deficiencies.
For lightning protection subsystems any discrepancies found to be beyond the ability of the ETs workforce to repair should be corrected by submitting a?
Shore Station Maintenance Request (SSMR)
Any changes to a facility’s lightning protection subsystem shall be documented using a?
Facilities Maintenance Report
How do you determine the number of lightning ground rods required for lightning protection?
The Number of down conductors; there should be one ground rod for each down conductor dedicated exclusively for lightning protection.
a type of storm which is regenerative in nature, and therefore has a tendency to last for several hours is called a _______ storm.
frontal storm
What is the minimum size of a lightning protection ground rod?
8-ft long by 1/2-inch in diameter
Due to _______ effects, all elements of lightning protection subsystem must be securely fastened.
mechanical
A facility’s fault protection subsystem provides personnel and equipment protection from?
exposure to excessive voltages or current flow
What two types of faults require the installation of overcurrent protection devices?
· Overcurrent due to current overload
· Overcurrent due to incidental short between phase conductors and equipment chassis
What are four types of current flow protection devices?
· Fuses
· Circuit breakers
· Ground Fault Sensors
· Ground Fault Circuit Interrupters.
In a Communications Electronics (C-E) facility, fault protection is provided by the what?
Earth electrode subsystem, the green safety grounding conductors, and other grounding and fault protection components
All grounding conductors that penetrate or cross a designated RF barrier or shield should be what?
bonded to the barrier or shield
Define "Grounded Conductor"
A grounded conductor is a conductor in a system or circuit that is intentionally grounded.
Define "Grounding Conductor"
A grounding conductor is used to connect equipment or the grounded circuit of a wiring system to the earth electrode subsystem.
The conductors used to interconnect all noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, at the service equipment or at the source of a separately
derived system are called what?
Equipment grounding conductors
The conductors used to connect equipment grounding conductors or grounded conductors to the earth electrode subsystem are called what?
Grounding electrode conductors
The materials used and the specifications required for grounding conductors are determined by what two factors?
· Their use in the facility’s ground system
· The ampere rating of the overcurrent protection device used in the circuits affected.
The grounding electrode conductors should be made of what types of metals?
· Copper
· Aluminum
· Copper-clad aluminum
The size of the grounding electrode conductor is determined by the size of what?
the largest entrance conductor
Although the NEC permits the use of metal ducts, cable trays, and metal raceways, they should not be used in lieu of what?
equipment grounding conductors
Whenever a single power source serves a single building, the safety ground (green wire) must be what?
grounded to the earth electrode subsystem
When a single power source serves more than one building, and if noise or hum is encountered in a C-E circuit or equipment, the neutral should be what?
lifted or removed from ground at the service disconnect
To ensure fault protection is maintained at any facility what should be installed?
fuses, circuit breakers, ground fault sensors, and Ground Fault Circuit Interrupters (GFCI)
Each ungrounded service conductor (phase lead) should have what?
overload protection provided by an overcurrent device such as a fuse
GFCIs have a very ______ and their sensitivity to detection of fault currents make these devices extremely valuable for personnel safety.
fast response time
GFCIs monitor the _____ and the ______ .
current supplied from the source, current returning from the load
NEC requires that GFCI's are installed where and with what amp rating?
15 and 20-ampere in bathrooms, garages and outdoor recepticals in famliy dwelling units.
MIL-STD-188-124B also recommends GFCIs be installed on what?
120-volt single-phase 15 and 20-ampere receptacles of C-E facilities.
Ground fault sensors operate in a manner similar to GFCI but primarily serve to to do what?
protect equipment from fault conditions
When a new facility is constructed, an initial site survey and inspection is conducted of the what?
entire facility’s ground system
After the initial inspection, maintenance of the fault protection subsystem should be conducted how often?
At least annually, or after major changes or additions to the subsystem are made.
The initial inspection or survey
of a facility's ground system establishes what?
A base or starting point by which the condition of the fault protection subsystem is measured.
The continuity between neutral and grounding conductor of a fault protection subsystem should be what?
- 1 Megohm or greater means the Neutral is connected properly.
- Less than 10 ohms means that the neutral is connected to ground somewhere other than the first service disconnect.
List the elements, such as the earth electrode subsystem, that comprise the fault protection subsystem.
Green safety grounding conductor, all non-current metal structures, overcurrent protection devices.
What is the difference between a “grounded” and a “grounding” conductor?
The grounded conductor refers to the neutral conductor, and the grounding conductor refers to the green safety wire.
List 4 materials that can be used as equipment grounding conductors.
Rigid metal conduit, intermediate metal conduit, flexible metal conduit, electrical metallic tubing.
What type of materials can be used for grounding electrode conductors?
Copper, aluminum, or copper-clad aluminum.
What is the maximum acceptable stray current level in a grounding conductor?
.1-amps
Signal circuits are grounded and referenced to ground in order to do what three things?
· Establish signal return paths between a source and a load
· Control static charge
· Provide fault protection
What are the three types of network configurations for the signal reference ground?
· Floating Ground
· Single-point Ground
· Multi-point or (Equipotential) Ground
What is the preferred signal reference ground network configuration for C-E facilities?
multi-point or equipotential ground
In a floating ground system the signal ground is what?
electrically isolated from the building ground and other conductive objects
What are the advantages of a floating ground system?
· Prevents noise that may be in the facility’s ground from being conductively coupled to the signal circuits
· Prevents noise currents in equipment cabinets from being coupled to the signal circuits
What are the drawbacks of a floating ground system?
· Static charge buildup on the isolated signal circuits may present a shock and/or spark hazard
· Danger of flashover between cabinet and signal system in the event of a lighting strike to the facility. This would cause insulation breakdown and arcing
· Power faults to the signal system can cause the system to rise to hazardous voltage levels relative to other conductive objects in the facility.
· Electrical isolation is difficult to maintain in a shore facility, thus it is not generally recommended for C-E facilities.
A single-point ground system is recommended for use in what type of electronic systems?
Low Frequency (up to approw. 300 kHz)
What is the advantage of a single point ground system?
Control of conductively-coupled interference by minimizing the effects of lower frequency noise currents that may be flowing in the facility ground.
What are the disadvantages of a single-point ground system?
· Single-point grounds are extremely poor grounds at RF frequencies because the ground impedance varies with frequency
· Grounds used become transmission lines at higher frequencies
· Every piece of equipment bonded to a single-point ground system becomes a tuned stub
· Requires long conductors in large installations
· Single-point grounds are not recommended for use in C-E facilities.
The Multi-Point Ground system is recommended for what type of electronic systems?
higher frequencies of 30 kHz and above.
To be effective, a multi-point ground system requires the use of what when ever the conductors exceed 1/8 wavethength at the highest frequency of concern?
an equipotential ground plane
What are two advantages of multi-point ground systems?
· Simplification of circuit construction inside complex equipment
· Easier interface of equipment employing coaxial cables since the outer conductor of the coaxial cable does not have to float relative to the equipment cabinet or enclosure.
What are the three disadvantages of the multi-point ground system?
· Exhibits transmission line characteristics at RF frequencies.
· Requires the use of equipotential ground plane.
· Care must be taken to ensure low frequency currents are not coupled into the signal circuits and create interference.
In high frequency environments, the equipotential ground plane is essential for what?
· Proper equipment operation
· Suppression of noise and static
· Reduction of electromagnetic interference (EMI)
· Reduction or elimination of noise in cables or conductors by the use of filters or bond straps by “shorting out” the noise field.
The equipotential ground plane can also present problems such as:
· Possible exposure to high potentials when metallic conductors (which are part of the ground plane) are not properly bonded. This high potential is in respect to earth
· May increase interference by providing conductive coupling paths or inductive loops.
An equipotential plane can consist of what three things?
· A copper grid embedded in the concrete floor or raised metal floor such as a computer floor
· A subfloor of aluminum, copper, phosphor bronze screen, or sheet metal laid underneath the floor tile or carpet
· Ceiling grid above the equipment. (overhead equipotential plane).
What type of equipotential ground plane will be installed during the construction of the new facility.
Grid Embedded in Concrete
Several types of raised computer floors are
manufactured but only one is acceptable as an equipotential plane what is it?
The bolted-grid “stringer” system
The bolted-grid “stringer” system computer floor provides what?
· An electrically continuous sheet at RF frequencies
· A low impedance path to earth at lower frequencies by connecting the equipment cabinets with bonding straps.
Construction of a computer floor equipotential plane consists of what three things?
· Drop-in panels
· Stringers
· Pedestals
What is the prefered material to be used for installing a equipotential ground plane in an overhead plane?
Phosphor bronze screen
Maintenance of the signal ground subsystem will consist of inspecting the conducting members of the subsystem for proper what?
Bonding and Grounding
Low frequency equipment should be connected to what type of ground system?
single point ground system
The ground terminal can be accomplished in one of several ways what are they?
· A pin in a connector
· A screw or pin on a terminal strip
· An insulated wire or an insulated stud
· A jack
· A feed through
The signal ground terminal should be marked with what?
a permanent yellow label or color code
The low frequency equipment must be checked to ensure that the insulation resistance of the equipment is at least how much resistance?
1 megohm
In a single-point ground there is how many paths for the signal reference to ground?
only one path
In high frequency equipment, the chassis is normally used as the what?
signal reference plane
In equipment where both lower and higher frequency circuits must share a common signal ground, the equipment must be what?
grounded as in higher frequency equipment
For low frequency equipment the resistance between the signal ground terminal and the equipment case should be greater than what?
1 megohm
For low frequency equipment the resistance between the green safety wire and the case should be what?
.1 ohm or less
In low frequency equipment possible causes for high resistance reading between the green safety wire and the case are?
· Green wire in power cord not connected to case
· Green wire not connected to bare metal
· Green wire not securely fastened to case
For high frequency equipment higher frequency reference point and planes are what?
Directly grounded to the chassis and the equipment case.
List the three types of signal ground systems
Floating ground, Single-point, Multi-point
List one disadvantage to using a floating ground system.
Static charge buildup on the signal ground can present a shock and spark hazard.
A practical Multi-point ground requires the use of an ____________ ________ plane whenever the conductors exceed ____ wavelength at the highest frequency of concern
Equipotential ground, 1/8
State one advantage to using a single-point ground system.
Helps control of conductively-coupled interference by minimizing the effects of lower frequency noise currents that may be flowing in the facility ground.
When inspecting a facility to determine the type of signal ground system, you inspect a piece of equipment that has a signal ground terminal which is isolated from its chassis. This tells you that this equipment should be connected to a _________-__________ ground system.
Single-point
What is a sudden, high-voltage spike in an alternating current system, caused by arching or lightning. Any short pulse attributable to external causes. Undesirable.
Transient
What is a device, such as spark gap or gas diode, employed to absorb a potentially destructive transient or overvoltage.
Surge Arrester/Suppressor
A ceramic silicon carbide, a non-linear resistance material, or a resistor made of this material. The resistance of a thyrite decreases sharply when the applied voltage is increased. Used for voltage regulation and surge suppression.
Thyrite
Any device or group of devices designed to protect
equipment from undesirable transient energy is referred to as what?
Transient Suppression Devices
Transients can be in the form of what?
repetitive voltage spikes such as produced by commutative, inductive, and capacitive load switching, or they can be random voltage spikes (such as those produced by lightning, power system failures, and electrostatic discharges).
Regardless of the cause, TSDs must be able to do what?
protect the equipment which they serve
transient energy can enter a facility or reach sensitive
equipment via many sources. They can enter through what means?
· Secondary AC power lines
· Telephone lines
· Data lines
· Control lines
· Coaxial transmission lines
· Other means
Operating characteristics of any TSD (Transient Suppression Device) includes what?
· Turn-on time
· Current dissipation capability
· Firing/Clamp voltage
In general, the higher the current handling capability of any TSD, (Transient Suppression Device), the ____the turn-on time of such device.
lower
TSDs (Transient Suppression Devices) can handle surge currents from ______ amperes depending on the type of discrete device used.
50 to 150,000
Most manufactures estimate the operating life of a TSD (Transient Suppression Devices) to be what?
10 years
Clamp voltage or discharge voltage is the voltage that appears across the input terminals and the ground terminal while conducting what?
a transient surge current to ground
Electronic equipment can also be the source of transients in other sensitive equipment. These sources can include:
· Motors
· Transformers
· Thermostats
· Fluorescent lighting chokes
· Starter coils
· Actuators
· Relay
· Other devices.
Most TSDs (Transient Suppression Devices) are made from only a few discrete components which include:
· Gas-filled spark gaps
· Metal-Oxide Varistors (MOV)
· Zinc-oxide Non-linear Resistors (ZNR)
· Solid State
· Hybrid of above components.
Gas-filled spark gaps can handle large amounts of current but usually have what?
a slow turn-on time and high clamp voltage
A Metal-Oxide Varistors (MOV) is essentially a what?
a back-to-back symmetrical diode with a characteristic similar to that of a zener
The Zinc-oxide Non-linear Resistors (ZNR) has several desirable characteristics. They are what?
A relatively fast turn-on time, relatively low clamping voltage, and has various levels of current dissipation capability.
Solid state arresters can be made to have turn-on times as fast as _____.
1 nanosecond
Solid state arresters have a low ______ but generally have a low _______.
clamp voltage, low current handling capability
olid state arresters can be made from what components?
· Silicon avalanche diodes suppressors (SAS)
· A combination of silicon avalanche diodes and silicon controlled rectifier (SCR).
Hybrid arresters are made from a combination of what three things?
MOVs, ZNR, and Gas-filled spark gaps.
What should be installed at the facility’s main service disconnect to protect a facility from the effects of lightning induced transients on the secondary AC service conductors.
A surge arrester
The need for telephone line protection is necessary because of what two factors?
· Of the threat of lightning strikes
· The possibility of power lines coming in contact with telephone lines.
This where the responsibility for maintenance switches from the telephone company to the Coast Guard.
The demarcation point
There are three types of telephone protectors, these are:
· Fused
· Fuseless
· Gas tube protectors
Gas tubes offer two major advantages they are what?
· consistent clamp voltage
· self-restoring capability
A drip loop to protect against rain should be how large?
One and a half inches
To protect coaxial transmission lines operating in the frequency range of up to 3 MHz, what may be employed at the entrance to the facility and at the equipment.
MOVs (Metal-Oxide Varistors) and Silicon Avalanche diodes
At the equipment entrance, a second level of protection should also be provided. This is accomplished with the use of what?
Bi-polar Silicon Avalanche diodes (SAS)
Thyrites require ______
maintenance and can handle large surge currents across their terminals.
little or no
Maintenance of TSDs (Transient Suppression Devices) is fairly _____ and will vary greatly depending on the type of equipment it is designed to protect.
limited
The proper distance between ball gap spheres is established by a ______ procedure, then recorded for future reference.
one time “trial-and-error” adjustment
State three ways transient energy enters a facility
Power lines, telephone lines, data lines.
State four causes of transient energy
Motors, transformers, thermostats, fluorescent lighting chokes.
How often should you inspect antenna tower ball gaps installed across the base insulator?
Once a year.
What type of discrete device would be best suited for handling large amounts of current?
Gas-filled spark gaps.
The power delivered to the load by three-phase power is ___________ the same.
A. never
B. always
C. sometimes
D. usually
B. always
A Wye-connection produces 1.73 times more line _______ than a delta connection.
A. voltage
B. current
C. loss
D. impedance
A. voltage
What is the maximum allowable resistance that a facility (non C-E) can have in respect to earth ground?
A. 2 ohms
B. 10 ohms
C. 25 ohms
D. 50 ohms
C. 25 ohms
In a Wye secondary arrangement, the voltage across any two lines is equal to ___________ .
A. 1.73 times phase voltage
B. 1.73 times phase current
C. phase voltage divided by 1.73
D. phase current divided by 1.73
A. 1.73 times phase voltage
Driven electrodes used in the Coast Guard must be at least __________ inch in diameter.
A. 8-ft long by ½
B. 10 ft. long by ½
C. 8 ft. long by ¾
D. 10 ft long by ¾
D. 10 ft long by ¾
For the protection of critical structures such as a C-E facility, a _________ cone of protection is required.
A. 1:1
B. 2:1
C. 3:1
D. 4:1
A. 1:1
Stray current on equipment grounding conductors should not exceed _________.
A. 1 milliamps
B. 10 milliamps
C. 100 milliamps
D. 1 amp
C. 100 milliamps
What type of device can handle large amounts of transient current?
A. Spark gap
B. MOV
C. ZNR
D. SAS
A. Spark gap
A type of network configuration which is best suited for equipment operating in the frequency range of up to 300 kHz.
A. floating ground
B. single-point ground
C. multi-point ground
D. equipotential ground plane
B. single-point ground
Adjustment of the ball gaps installed in a transmitting antenna should be adjusted during periods of ____________ .
A. cold weather
B. hot weather
C. high relative humidity
D. thunderstorm activity
C. high relative humidity