ABYC Flashcards
1
Q
what kind of crimper do you use for battery conductors
A
box
2
Q
What is the amp limit for fricton connectors?
A
20
3
Q
What precautions must you take with continuously energized components such as battery terminals and wire terminals
A
they need to be physically protected,ie rubber boot, to prevent accidental shortage
4
Q
What are many of the requirements in E-11 intended to do?
A
control and minimize resistance so that sufficient amperage can be achieved for a given voltage. ie wire sizing
5
Q
how do you find voltage using ohms law
A
amps X ohms
6
Q
how do you find amps using ohms law
A
voltage / ohms
7
Q
how do you find ohms using ohms law?
A
volts/amps
8
Q
what happens to amperage if resistance increases?
A
amperage decreases and vice versa
9
Q
how do you find watts using the power equation?
A
volts X Amps
10
Q
how do you find volts using the power equation?
A
watts/amps
11
Q
how do you find amps using the power equation?
A
watts/volts
12
Q
What are key elements of an electrical circuit?
A
- source of power
- over current protection
- switch (sometimes integrated with a circuit breaker)
- conductors
- load or appliance
- return path to the source of power
13
Q
what is the one exception for over current protection in a circuit?
A
Cranking motor
14
Q
what are the two different type of circuits in marine wiring?
A
series and parallel
15
Q
what is the benefit for devices in a parallel circuit?
A
each appliance sees full battery potential, making the circuit as a whole less resistive compared to a series circuit
16
Q
how do you find the total resistance in a series circuit?
A
add all the resistance values in the circuit
17
Q
what do you call the voltage that changes across each load according to resistance in a series circuit?
A
voltage drop
18
Q
how do you find the source voltage in a series circuit?
A
add the individual voltage drops in the circuit
19
Q
T or F? The amperage draw in a series circuit will be the same through out the circuit?
A
True
20
Q
T or F? The total circuit resistance is less than the smallest individual resistance in a parallel circuit?
A
True
21
Q
T or F? The voltage drop across each resistor will be different in a parallel circuit.
A
False
22
Q
In a parallel circuit, when could amperage draw be different across each resistor?
A
if the resistance value varies (ie different devices)
23
Q
how do you find the total amperage draw of a parallel circuit?
A
add all the separate amperage draws
24
Q
what is it called when voltage is lost as if travels through a circuit?
A
voltage drop
25
what are three general categories for a short circuit
1. short circuit to ground
2. intercicuit short
3. internal short (within a component)
26
which short is the most dangerous and why?
short circuit to ground because there will be high current due to lack of resistance.
27
what can prevent a short to ground?
a fuse or breaker
28
Because starter batteries aren't fused, what are some extra precautions we must take?
1. battery cables have boots or covers on all terminal points
2. cables are properly supported and have chafe protection
3. cables avoid touching the engine block
29
what are common causes of inter circuit shorts?
chafe
errant screw
30
what are some symptoms of intercircuit shorts?
odd symtoms like lights that are glowing dimly
things having trouble working
these may or may not trip a breaker
31
What usually causes an internal short?
water migration into a device
| device has been installed without proper ventilation causing overheating and insulation breakdown
31
What usually causes an internal short?
water migration into a device
| device has been installed without proper ventilation causing overheating and insulation breakdown
32
how many watts = 1 horsepower?
746
33
What is a Gausmeter used to measure and what is this good for?
The amount of current running through a wire based on its magnetic field. its good for detecting the sources of interference problems with magnetically sensitive equipment as well as establishing a safe amount of space for installation
34
What is the most common fault?
unwanted open circuit
35
what does EMF stand for?
Electro magnetic feild
36
what is the primary problem with a series circuit with multiple loads?
voltage drop through the circuit
37
what are the main causes of excessive electrical resistance?
under sized wire, loose connections, and corrosion
38
What assumptions can be made when it comes to color coding on established ac wiring?
assume nothing, any color can be used. the standard is green for grounding, black for ungrounded, white for grounded.
39
what do we know about the conductivity of different metals?
different metals conduct heat and electricity more or less than other metals, this explains why certain metals are used in certain circumstances. IE: Silver is more conductive than copper, but not by much and copper is much cheaper, which is why we use it in wire. Tin is not very conductive at all, but is often used at a plate for corrosion purposes
40
What is considered the best tool for testing whether or not a circuit has a complete connection?
TDR ( time-domaine reflectometer)
41
What special things can a TDR do?
pin point location or short and open circuits within 1-4"
42
How does a TDR work and why is it different from other devices that test continuity?
Like the other devices, by sending a signal down the conductor, the difference is the TDR has a computer that reads the signals return, all you have to do is plug in the Vp ( velocity of propagation) depending on the size and type of the conductor.
43
What is the downfall of a TDR?
it will not function in short runs (less than 9 Ft) and only works with paired wire runs (which most of them are)
44
what is a Fox and hound?
Signal generator that uses a probe to follow the wire
45
Where are most wiring related problems and what can help fix this problem?
Most issues occur at termination points. Matching crimp terminals to proper wire sizes, and using the correct crimp size and tool designed for the connector are important.
46
what considerations should be made when stripping insulation?
use an appropriate tool as not to damage the strands of wire.
47
how much wire should protrude on a typical crimp connection?
just a little bit. STANDARDS DO NOT SPECIFY ANY PARTICULAR LENGTH
48
what is the only way to test a crimp?
minimum pull test values
49
why do we not want AC and DC conductors twisted together?
Heat build up
50
if you are unable to size a wire specifically to its need, what should you do?
round to the next size larger (which would be smaller in number)
51
Why do we size AC wire and what determines this?
We are concerned about heat build up. We size the wire based on bundle size and amperage.
52
what kind of terminal conductors should we use
ring or captive spade. Friction types are allowed if: circuit rated no more than 20 amperes, designed to meet the requirements of UL310 or UL1059, the voltage drop does not exceed 50 milivolts, and connection does not seperate if subjected to 1 minute of 6lb tensil force
53
what is the minimum temperature rating for cable in engine room spaces?
167F (75C)
54
what are the two main categories of batteries?
deep cycle and cranking
55
what are characteristics of a cranking battery?
they have more, thinner plates, within each battery cell to help deliver higher amperage to facilitate the needs of starter motors, but only for a short period of time. The thin plates also help them recharge more quickly, this becomes especially important when charging in parallel with the house bank by a single charging source.
56
What are the characteristics of a deep-cycle battery?
They offer the ability to deliver a moderate amount of amperage over a longer period of time and will suffer less when brought to a deeper level of dis-charge, which is also why it takes them more time to recharge
57
when recharging combined battery banks, what are two options of how to go about doing this?
1. Remote sensing for battery chargers and remote alternators
2. Voltage sensing for battery combiners/isolators
58
when combination charging with conventional diode type battery isolators, what can we do to ensure the deep cycle batteries get charged long enough to get back to %100?
sense voltage on the deep cycle battery side
59
What are the major differences between modern battery combiners and the traditional diode isolators?
They can be sensed on either the deep cycle or starter side because they do not suffer from the inherent voltage drop of a diode (0.7V). For greatest efficiency battery voltage sense wiring is placed directly on the house side ensuring minimum voltage drop.
60
What does SVR stand for? And what is a common charactaristic?
Sealed valve regulated. Immobilized electrolyte format.
61
what are 2 types of SVR batteries?
Gel cell and Absorbed Glass Matt (AGM)
62
What is the difference between gel-cell and AGM?
Gel cell: electrolyte is a paste
| AGM: sulfuric acid electrolyte is compressed tightly against battery plate surfaces via a diaper
63
What does a hydrometer do?
measures the specific gravity of the fluid extracted from the battery cell meaning the float will rise and fall depending on the density of the electrolyte
64
what is acceptible gravity for a fully charged battery?
1.260-1.285
65
Why do we do a Hydrometer test?
to compare the cells of a battery to see if one or more indicated a much lower gravity than the other. Anything more that .05 lower, is indicative of a cell that is beginning to fail. If all cells show equally low readings it is indicated that the battery is discharged and needs to be recharged and retested.
66
To ABYC standards, if one cell in a battery is bad, what should you do?
replace it
67
How long should a battery rest before testing?
8-12 hrs for best results but a minimum of 30 minutes will do.
68
why don't we combine different battery types?
because all batteries have different discharge and recharge qualities and batteries discharge into each other. The strong support the weak diminishing the whole groups strength.
69
when picking a battery charger, what must you keep in mind as it relates to the type battery you are charging?
that you will not over charge your battery. For example alternators are often too strong for what a gel cell can handle
70
what should be used to clean battery terminals?
wire brush
71
What are some options of cleaning up battery acid?
baking soda, spray on battery acid neutralizers ( which have the advantage of changing color in the presence of acid
72
What is the best corrosion inhibitor for battery terminals?
dry film
73
what can a high current series/parallel switching solenoid be good for and what is a common issue?
getting a 24V start with a 12V house bank. The issue is that over time the arc that occurs when they are switched may ultimately create an open circuit in the system, a normally closed contact point becomes open resulting in one of the batteries in the system not charging and eventually going dead
74
what is a battery equalizer?
electronic control boxes designed to combine batteries in order to distribute mixed voltage where it is needed. it provides an equal charge to all connected batteries and will balance the batteries during discharge.
75
What is an equalization cycle?
typically done with AGM batteries the equalization cycle is a controlled overcharge into the battery to initiate a chemical reaction that rattles any accumulated sulfate particles off the plate surface and back in to the electrolyte solution. this is done to equalize the specific gravity levels.
76
What must we do at ANY AC power source?
Ensure that there is a neutral-ground connection.
77
Why should you never attempt to jump or connect a battery charger to a frozen battery?
Because will be short circuited internally and may explode.
78
Why can a fully discharged battery freeze?
Because the electrolyte becomes mostly water because the sulfuric acid has been absorbed into the plate material
79
Why must deteriorated battery cable connections be reterminated ASAP?
because of extreme amperage capacity, loose or damaged connections can easily generate enough heat to start a fire
80
What basic guidelines do you need to follow when installing a battery?
less than one inch of movement.
provide proper means to contain spilled electrolyte
proper venting for the hydrogen gas, EVEN FOR SEALED BATTERIES
81
What must battery mounting materials be able to with stand?
electrolyte attack
82
what is the pull test for a secured battery?
90lbs or twice the battery weight (whichever is less) in every possible direction for one minute
83
What measures should be taken if a metallic fuel line or fuel system component is within 12" of a batteries surface?
cover it with Dialectric grease or non conductive material. covering the batteries will not suffice as the covers must be removed to make connections, thus exposing a potential hazard.
84
When can you use a soldered connection that joins a battery terminal connector to a conductor?
if the length of the soldered joint is 1.5 X the diameter of the stranded portion of the battery conductor
85
At what wire size is it inappropriate to use wing nuts on battery terminals?
Anything larger than 8AWG
86
At what CCA or AH rating is a battery switch required?
800CCA or 100AH
87
How do you pick a battery switch according to cranking/starting rating?
The rating shall not be less than the MAX cranking current of the largest engine it serves
88
How do you pick a battery switch based on its minimum continuous rating?
the rating shall be at least the total of the ampacities of the main OCPD connected to the battery switch of the ampacity of the feeder cable to the switch, whichever is less.
89
how does an alternator work?
magnetic induction
90
How does the voltage regulator in a charging system work?
controls the strength of the magnetic field inside the alternator to accommodate the demand load variations placed on the alternator.
91
What is the strength of the magnetic field within a wire directly proportional to?
The amount of current flowing through that wire.
92
True or False -
| AC current produced by an alternator can charge/recharge batteries
False - the AC current must be converted to a useful form of DC
93
What tool allows you to see what various electrical waveforms look like?
An oscilloscope
94
What amount of AC leakage past the diodes is normal?
A maximum of .4V AC is acceptable
95
What is the concern of an alternator's rectifier or diodes weakening, and AC leakage exceeding the acceptable value?
The alternator can become a source of radio frequency interference, which may affect the performance of electronic gear.
96
What does the stator portion of the alternator do?
It is the stationary part of the rotary system, where AC is induced.
97
What is the significance of the rotor portion of the alternator?
It is where the field windings are located and is the actual electromagnet in the system.
98
For batteries/banks with a CCA rating greater than 2200CCA or 500 AH, its OCPD should have an AIC rating that is?
At least as great as the battery manufacturers short circuit rating or min of 20ka at 125 VDC or higher
99
What is the purpose of a remote switch for a battery and how does it work?
To get access to a switch outside machinery spaces without using expensive heavy gauge wire. By using high-current latching contactors mounted close to the batteries but controlled by a safely located remote switch
100
what percentage of fires are caused by faulty electrical systems and incorrect rating of OCPDS?
55
101
what is the definition of SHEATH?
a material used as a continuous protective covering such as overlapping electrical tape, woven sleeving, molded rubber, molded plastic, loom or flexible tubing around one or more insulated conductors.
102
What does the voltage regulator on an alternator do?
It controls the strength of the magnetic field in the field windings. It constantly adjusts the amount of voltage entering into the field windings based on what it senses for voltage, in effect battery state of charge. The regulator helps to control alternator voltage and current output.
102
What does the voltage regulator on an alternator do?
It controls the strength of the magnetic field in the field windings. It constantly adjusts the amount of voltage entering into the field windings based on what it senses for voltage, in effect battery state of charge. The regulator helps to control alternator voltage and current output.
103
What is the rectifier in an alternator?
A grouping of diodes which convert the AC sine wave into usable form of DC. Diodes are semiconductors which only allow current to flow through them in one direction.
104
Because the rectifier generates heat and need to be kept cool, what precautions should be taken in terms of the fan?
Ensure the cooling fan is drawing cool air from the back of the unit and pulling it through. The rectifier is in the back and so cool air hitting the rectifier first will ensure it is kept cool.
105
what does not need to be considered when rating a battery switch?
in-rush amperage from things like the starter battery
106
what does "Trip Free" mean?
a resettable OCPD designed so that the means of resetting cannot over ride the current interrupting mechanism
107
True or False. It is recomended that we use "trip free" breakers?
True
108
What is a conductance tester and what are some benefits of using one?
A conductance tester, is a new tool used to test batteries. It will perform comprehensive charging system and starting system tests, as well as diagnose voltage drop and provide an estimated longevity. Some benefits are: you don't have to recharge your batteries before testing, they don't induce a heavy load on the battery, so high amperage is not a safety concern.
109
how does a conductance meter work?
By sending a low level pulsating signal through battery cell plates from post to post. the amount of time this takes is interpulated by a micro processor into a conductance value and then into a CCA value. this takes about 5-10 seconds. As a battery ages, its resistance increases reducing its conductance.
110
when using a conductance meter, at what percentage of it's initial rating should we replace a battery?
80%
111
when should an AC panel board be grounded?
when it is metal
112
T or F? you must provide a warning label at the boat's main electrical panel indicating that there is an inverter installed?
True
113
T or F? provisions must be made to prevent backfeeding of any source that is not intended to be enegized.
True. for example, we must prevent generators from backfeeding into shorepower.
114
how quickly must backfeed protection operate after the disconnection of the input AC power source?
100 milliseconds
115
What should be taken into consideration as it pertains to cooling fans on alternators?
Cooling fans are directional, and so are engines/alternators. Canted blades must spin in the proper direction to ensure the alternator is being cooled, and not drawing warm air into it.
116
What is the max RPM of most alternators that should not be exceeded?
14,000 rpm
117
Why is proper belt tension and pulley alignment important in alternators?
The belts can walk off the pulleys on the first rotation. This is especially important with serpentine belts.
118
What do the standards require you to consider when mounting battery chargers?
They should be mounted high enough to avoid any accumulation of bilge water or splash, and they should be mounted in an adequately ventilated area.
119
where must you have a Neutral-ground connection?
At any AC power source, but only at the power source
120
When do inverters not have a neutral ground connection?
when they are not in invert mode, ie: plugged into shore power and not creating AC power, the inverter will automatically disconnect the neutral-ground connection.
121
If a battery charger is not labeled ignition protected, where should it be mounted?
In a high/dry area with adequate ventillation OUTSIDE of a gasoline-powered engine room.
122
Why is it important not to mount battery chargers or inverters directly over batteries?
Corrosive vapors that accumulate near the top of batteries while being charged can migrate into the inside of the charger case, potentially damaging the unit and causing an internal short circuit.
123
what is the min. distance they OCPD should be from the shore power inlet on the boat?
10ft
124
What two things must a metal-cased battery charging or inverter unit contain?
1. An AC grounding conductor, attached to the case in the event of an AC-case short circuit
2. A DC case ground, which should not be more than 1 gauge size less than the DC current-carrying conductor from the output side of the charger, or in the case of an inverter, the combined DC feed and return when in charge mode.
125
What is required of metallic inlets on metallic boats using an isolation transformer ?
they should be insulated from the boat
126
what is required of inlets on non metallic boats using an isolation transformer or galv. isolator?
it shall be insulated from metallic components connected to the boats ground
127
Wind and Solar power generators require what two things?
1. Voltage regulation. Both devices can have output voltages that approach 20V
2. Diodes to prevent back-feeding of battery power back to the generators.
128
where is the the shore powers neutral ground connection?
through the shore power cable back to the transformer on the shore side
129
Solar panel arrays whose output voltage is greater than 50 volts should be avoided for what reason?
possibility of electrocution can occur
130
What is the maximum trip amperage and time for an ELCI?
the trip level should be a max. of 30mA and a max of 100ms to avoid nuisance trips
131
What is a self-limiting alternator?
When the generator/alternator/wind turbine reaches a certain voltage output it shuts down the magnetic field and ceases to send current to the inverter or battery.
132
can you put insulated conductors directly in clamps or straps?
no, it needs to be protected by loom or wrapping.
133
What does an RCD do?
detects equipment ground fault leakage current and disconnects all current carrying conductors from the supply source at a present trip threshold
134
what does RCD stand for?
residual current device
135
what does GFP stand for?
Ground fault protector
136
should you connect neutrals together from multiple inlets?
no, never
137
how do you isolate two shore power cables?
by completely isolating the inlets or via a break before make type switching device
138
what is the only device permitted to be installed with the AC grounding conductor?
The galvanic isolator
139
what is the purpose of the galvanic isolator?
to block low level DC current from coming in through the AC safety ground when the boat is connected at the dock. This helps prevent corrosion.
140
what does "fail safe" mean in terms of galvanic isolators?
the device will never fail open, inturn violating the ground.
141
How do you rate the galvanic isolator?
it should not be less than the rating of the main shore power circuit breaker
142
how close to the galv. isolator do you need wire support?
6"
143
what ampicity rating should wire terminals have on galvanic isolators?
an apicity that is 135% of its nominal rating, IE: 30x1.35=41amps
144
do you have to torque bolt or stud connections on galv. isolators?
yes
145
how do isolation transformers make power on the boat side to ensure there is proper polarization, grounding, galvanic isolation, and safety for the people on board?
Magnetic induction
146
what is the difference between an isolation transformer and a polarization transformer?
Polarization transformers don't have galvanic isolation
147
what are some advantages of high frequency switch mode transformers over other transformers?
they are lighter, they typically run at much cooler temperatures, and tend to have less electromagnetic and RF emissions
148
where in the circuitry does the OCPD belong when installing an isolationt ransformer?
In the feeder (from the dock) wire
149
How do you size the OCPD for on board transformers?
they shall be no more than 125% of the primary current of the transformer
150
In what circuit are reverse polarity indicating devices required?
in all 120VAC systems. It will respond to the reversal of the ungrounded and grounded contuctors
151
The reverse polarity indicating devices need to have how much resistance to continue working?
at least 25,000 ohms
152
What is one tool for checking for reverse polarity starting at the pedestal?
sure test or circuit analyzer
153
T or F reverse polarity can result in shocking people on board
true
154
when there are low AC voltage issues on the boat, where do you start when diagnosing the issue?
the source of power
155
at what temperature is it considered an issue when using an infared camera or thermal reader to find resistance?
25F above the median temp
156
if people are getting shocked on the boat what is the first step a technician should take?
check polarity at the shore cord
157
what are 3 reasons a galvanic isolator could stop working
shorted isolator diode
improper current rating of the isolator
an onboard neut.- ground connection
158
what is the major difference between generators and alternators?
with generators we do not want to rectify the AC current produced and we need to maintain a controlled RPM under all load conditions to ensure an exact voltage and frequency output
159
what is the specific gravity of pure water?
1.0
160
what is a typical charging system voltage range?
12.6-14.1 VDC
161
What rise in voltage reading can you expect when charging a battery?
.5 VDC
162
what tools do you typically need for trouble shooting generators?
a multimeter and a manual, megohmeter
163
what is a common reason for low AC output voltage in generators?
failure or any type in the exciter windings and diodes
164
how do you do generator performance test?
frequency and voltage under both no load and full load circumstances
165
What do megohmeters do?
confirm the integrity of the winding insulation inside a generator or motor, they can also be used to check everyday appliances for ground leaks.
166
how to megohmeters work?
By inducing a high voltage into the winding coils which will cause a leak to be identified quickly
167
what is an acceptible reading on a megohmeter?
1 megohm or more!
168
if you have a short in your field winding what will your DVOM ohm meter read?
OL or infinity
169
how much stress should a wiring lead to the generator set be able to withstand?
9kg(20lbs) for one minute with out any displacement and therefore need strain releif and chafe protection
170
what must happen for seamless transfer in AC?
Syncronization
171
what is the limit for backfeed power in generators?
15% of the rated out put
172
what is the minimum voltage rating for AC condutcors on boats?
600V
173
What is the minimum rating of AC flexible cords such as extension cords?
300V
174
what is the minimum temperature rating of AC conductors?
140F
175
do AC conductors have to be stranded copper on boats?
yes
176
what tool must you use when checking output voltage of a non-sinusoidal inverter?
True RMS voltmeter
177
how many inches before you have to start derating a bundle?
24
