ACM-170 ELECT SYS - (GENERAL QUESTIONS) Flashcards
(186 cards)
1
Q
What is the primary function of a generator in aircraft?
A
To convert mechanical energy into electrical energy by electromagnetic induction
Generators provide energy for the operation of most electrical equipment on aircraft.
2
Q
What are the two types of generators based on the type of current they produce?
A
DC generators
AC generators
3
Q
What type of generator is commonly used in older aircraft?
A
DC generator
4
Q
How are DC generators typically driven in aircraft?
A
By the engine(s)
5
Q
In most cases, how many generators are driven by each engine in an aircraft?
A
One generator
Some large aircraft may have two generators driven by a single engine.
6
Q
Who demonstrated that a magnetic field can create current flow?
A
Michael Faraday
In 1831, Michael Faraday’s experiments led to this significant discovery, which is fundamental to generator operation.
7
Q
What is the basis for the operation of the generator?
A
The ability of a magnetic field to create electric current
This principle was demonstrated by Faraday’s experiments in 1831.
8
Q
What equipment is used to show how an electric current is created by a magnetic field?
A
- Several turns of wire
- Cardboard tube
- Galvanometer
The galvanometer measures the current flow induced by the magnetic field.
9
Q
What happens to the galvanometer when a bar magnet is moved through the tube?
A
It deflects from its zero position
This indicates that current is being generated as the magnet’s lines of flux are cut by the wire.
10
Q
What indicates no current flow in the circuit?
A
A reading of zero on the galvanometer
This occurs when the magnet is stationary inside the tube.
11
Q
What occurs when the magnet is moved through the tube in the opposite direction?
A
The galvanometer indicates a deflection in the opposite direction
This shows that the direction of current flow is affected by the direction of movement.
12
Q
What is required for current to flow in relation to the conductor and the magnetic field?
A
Relative motion between the wire coil and the magnetic field
Current flows as long as there is movement, whether the magnet is moved or the coil is moved.
13
Q
What does the strength of the induced current depend on?
A
The strength of the magnetic field and the speed at which the lines of flux are cut
These factors determine how much electromotive force (EMF) is induced.
14
Q
What is induced when a conductor is moved through a magnetic field?
A
An electromotive force (EMF)
This EMF is responsible for the flow of current in the conductor.
15
Q
How is the direction of the induced EMF determined?
A
By the direction the conductor is moved in relation to the magnetic flux lines
The induced EMF’s polarity depends on this relationship.
16
Q
What rule helps determine the direction of the induced EMF?
A
The left-hand rule for generators
This rule uses the position of fingers to indicate the direction of EMF, magnetic flux, and conductor movement.
17
Q
What does the left index finger represent in the left-hand rule?
A
The direction of the magnetic lines of flux
It is pointed from north to south.
18
Q
What does the thumb represent in the left-hand rule?
A
The direction the conductor is moved through the magnetic field
This helps in determining the induced EMF direction.
19
Q
What happens when a conductor in the shape of a single loop is rotated in a magnetic field?
A
A voltage is induced in each side of the loop
Even though the sides cut the magnetic field in opposite directions, current flows in one continuous direction.
20
Q
What effect does rotating a loop have on the induced EMF?
A
It increases the value of the induced EMF
Continuous current flow in the loop is achieved despite opposite cuts of the magnetic field.
21
Q
What does the index finger represent in the generator left-hand rule?
A
The direction the lines of magnetic flux travel
This rule helps to determine the direction of induced EMF based on the movement of conductors in a magnetic field.
22
Q
What does the thumb indicate in the generator left-hand rule?
A
The conductor’s direction of movement
The left-hand rule is a mnemonic for understanding electromagnetic induction.
23
Q
What does the second finger represent in the generator left-hand rule?
A
The direction of induced EMF
This is crucial for predicting the behavior of induced current in generators.
24
Q
What happens to the induced EMF when the loop is rotated half a turn?
A
The induced EMF in each wire reverses its direction
This occurs because the sides of the loop cut the magnetic field in opposite directions.
25
What is the result when the sides of a wire loop are parallel to the magnetic lines of flux?
The induced voltage causes current to flow in one direction
## Footnote
Maximum voltage is induced when the wires cut the lines of flux at right angles.
26
When is maximum voltage induced in a simple generator?
When the wires are cutting the lines of flux at right angles
## Footnote
This position allows for the most flux lines to be cut per second.
27
What happens to the induced voltage as the loop approaches the vertical position?
The induced voltage decreases
## Footnote
This occurs because both sides of the loop become perpendicular to the lines of flux.
28
What occurs when the loop is vertical in terms of induced voltage?
There is no induced voltage
## Footnote
At this position, the wires travel perpendicular to the magnetic lines of flux.
29
What is the effect of rotating the loop beyond the 90-degree point?
The number of flux lines being cut decreases until the induced voltage becomes zero
## Footnote
This cycle of cutting flux lines is critical for understanding generator operation.
30
What are the components of a simple generator?
1. Pole pieces
2. Armature
3. Slip ring
4. Brushes
## Footnote
These components work together to convert mechanical energy into electrical energy.
31
What occurs at the 90-degree point during the rotation of the loop?
The maximum number of flux lines is being cut, but in the opposite direction
## Footnote
This leads to a reversal of the polarity of the induced voltage.
32
What is the voltage behavior of a generator as it rotates 360 degrees?
The curve increases from zero at 0 degrees to maximum positive at 90 degrees, decreases to zero at 180 degrees, increases to maximum negative at 270 degrees, and returns to zero at 360 degrees.
33
What type of current is produced by a single loop rotating in a magnetic field?
Alternating current.
34
What component converts alternating current to direct current in a generator?
Single commutator.
35
At what point does the armature in a DC generator produce maximum induced EMF?
When the armature is parallel to the lines of flux.
36
What is the effect of increasing the number of loops in a DC generator?
It reduces the ripple in DC voltage.
37
How many commutator segments are required for two loops in a generator?
Four segments.
38
True or False: Increasing the number of loops increases the maximum value of generated voltage.
False.
39
What is the purpose of the field frame in a generator?
It completes the magnetic circuit and acts as mechanical support.
40
What is the function of the pole shoes in a generator?
They concentrate the lines of force produced by the field coils.
41
What is the role of the field coils in a generator?
To produce the magnetic field around the pole shoes.
42
What are salient poles in generator design?
Pole pieces that project inward from the frame to reduce air gap width.
43
What are the components of the armature assembly in a DC generator?
Armature coils, commutator, and associated mechanical parts.
44
What is lap winding in a generator?
A method where one end of two coils connects to each commutator segment.
45
What material are the brushes in a DC generator made from?
High-grade carbon.
46
What is the main disadvantage of series-wound generators?
Poor voltage regulation capabilities.
47
How are the field windings connected in a shunt-wound generator?
In parallel with the external circuit.
48
What is the formula to calculate the IR drop in a shunt-wound generator?
IR drop = current x armature resistance.
49
Fill in the blank: The variation in DC voltage is called _______.
[ripple].
50
What is the consequence of low spring tension on brushes in a generator?
It can result in brush arcing.
51
What is the primary function of the commutator in a DC generator?
To ensure current flows in the same direction despite reversal in the loop.
52
What formula is used to calculate the IR drop in the armature winding?
IR drop = current x armature resistance
## Footnote
This formula highlights how voltage loss increases with load.
53
What happens to output voltage as the load increases in a shunt-wound generator?
Output voltage decreases due to increased IR drop
## Footnote
This is because the current in the field coils decreases with a decrease in output voltage.
54
How is the output voltage controlled in a shunt generator?
By inserting a rheostat in series with the field winding
## Footnote
This configuration adjusts field current to manage output voltage.
55
What is a characteristic of shunt-type generators?
Suitable for light to medium duty use on aircraft
## Footnote
They have been largely replaced by DC alternators.
56
What components make up a compound-wound generator?
A series winding and a shunt winding
## Footnote
This combination utilizes the characteristics of each type.
57
What is the effect of adding load to a compound-wound generator?
Increases armature-circuit and series-field circuit current
## Footnote
This leads to an increase in field flux.
58
What is a flat-compound generator?
A generator where no-load and full-load voltages are the same
## Footnote
This indicates a specific degree of compounding.
59
What distinguishes cumulative-compounding from differential-compounding in generators?
Cumulative-compounding aids the shunt field, differential-compounding opposes it
## Footnote
This affects the output voltage characteristics.
60
What is the purpose of inter-poles in some generators?
To counteract the effects of field distortion
## Footnote
Interpoles help maintain the neutral plane during load changes.
61
What is the typical rating format for a generator?
Rated in amperes at a specified voltage
## Footnote
Example: 300 amps at 28.5 volts.
62
The generator drive on a reciprocating engine is usually geared between _____ and _____ times the engine crankshaft speed.
1-1/8
1-1/2
63
What is the 'coming-in speed' for most aircraft generators?
Typically around 1,500 rpm
## Footnote
This is the speed at which generators start producing normal voltage.
64
Efficient operation of electrical equipment in an aircraft depends on a _____ that varies with a system's load requirments.
voltage supply
65
Amont the factors that determine the voltage output of a generator, the __________ is the only one that is conveniently controlled.
strength of the field current
66
What is the role of the rheostat in generator voltage regulation?
Controls the strength of the field current
## Footnote
Adjusting resistance affects the output voltage.
67
What happens to the output voltage when resistance in the field circuit is increased?
Less current flows, decreasing the output voltage
## Footnote
This is due to a weaker magnetic field.
68
Fill in the blank: The principle of generator operation states that as load increases, additional _______ must be supplied.
field current
## Footnote
This is necessary to increase voltage output and overcome the turning force.
69
What type of voltage regulator uses a solenoid to connect or remove the field rheostat?
Vibrating-type voltage regulator
## Footnote
This setup maintains average voltage with load changes.
70
What happens when switch K is closed in a generator system?
A short circuit is placed across the field rheostat, causing the field current to increase and the output voltage to rise.
71
What role does capacitor C play in a generator system?
Helps eliminate sparking.
72
How does a vibrating-type voltage regulator maintain generator output?
Contact B opens and closes several times per second.
73
What are the three units included in a three-unit regulator for light aircraft?
* Current limiter
* Reverse current cutout
* Voltage regulator
74
What is the purpose of a reverse current cutout in a generator system?
Disconnects the battery from the generator when the generator output is lower than the battery output.
75
What occurs when the battery attempts to drive the generator as a motor?
This action is called motoring the generator.
76
What are the voltage regulator 3 coils?
1. Voltage Regulator Coil
2. Current Limiter Coil
3. Reverse Current Coil
77
What type of regulator is required for heavy-duty generator systems?
Carbon-pile voltage regulator.
78
How does the resistance of a carbon pile voltage regulator change?
Resistance varies inversely with the pressure applied.
79
What creates pressure on the carbon pile in a carbon-pile voltage regulator?
Two opposing forces: a spring and an electromagnet.
80
What happens if generator voltage rises above a specific amount in a carbon-pile regulator?
The pull of the electromagnet increases, decreasing pressure on the carbon pile and increasing its resistance.
81
What is the purpose of routine inspection and service for generators?
To keep a generator in good working order.
82
What should be inspected during the 100-hour and annual inspection of a generator?
1. Security of mounting
2. Oil leaks
3. Electrical connections
4. Brushes and commutator cleanliness
5. Commutator wear and pitting
83
What indicates that a generator has overheated?
Presence of solder particles around the commutator.
84
What is the first step if a DC generator is unable to keep an aircraft battery charged?
Check the aircraft electrical system associated with the battery and generator.
85
How can residual magnetism be restored in a generator?
By momentarily passing current through the field coils in the same direction that it normally flows.
86
In an 'A' circuit generator, where should the positive terminal of the battery be touched to restore residual magnetism?
To the armature.
87
What test can determine if a generator produces voltage with the regulator shorted?
Operate the engine at high speed and bypass the voltage regulator with a jumper wire.
88
What are the steps involved in generator overhaul?
1. Disassembly
2. Cleaning
3. Inspection and repair
4. Reassembly
5. Testing
89
What must be followed during disassembly of a generator?
Manufacturer's overhaul manual instructions.
90
What is the purpose of a growler in generator testing?
To test for open circuits and shorts in the armature.
91
How can an armature be tested for shorts using a test lamp?
One lead is touched to the armature shaft and the other to each commutator segment.
92
What should be done to a slightly roughened commutator surface?
Smooth it using No. 000 sandpaper.
93
What happens if the wrong solvent is used during cleaning of electrical parts?
It could remove lacquer-type insulation, resulting in short circuits after reassembly.
94
What must be ensured during the reassembly of a generator?
All internal electrical connections are properly made and secured.
95
What is the purpose of pigtails on generator brushes?
To conduct current and help eliminate any current in the brush springs that could alter its spring action
## Footnote
Pigtails also minimize sparking caused by movement of the brush within the holder.
96
When should generator brushes be replaced?
At overhaul or when half-worn
97
How is a new brush seated in a generator?
By using No. 000 sandpaper to contour the brush to maximize contact with the commutator
98
What is the acceptable pressure exerted by a carbon, graphite, or light metal brush on the commutator?
1-1/2 to 2-1/2 pounds
99
What should be done after a generator has run for a short period?
Reinspect the brushes to ensure no pieces of sand are embedded
100
What should never be used for seating brushes or smoothing commutators?
Emery cloth or similar abrasive
101
What is the purpose of operational testing of generators?
To flash the field and ensure proper operation before installation
102
What is the maximum allowable voltage drop in the main power wires from the generator to the bus bar?
2 % of the regulated voltage
103
What is the maximum continuous electrical load permitted in a system relative to the generator's output?
80 % of the total rated generator output
104
What feature helps prevent damage to the generator or electrical system if a generator quits producing current?
Generator master switch
105
What are the two types of alternators used in aircraft?
* DC alternator
* AC alternator
106
What is the main difference between DC alternators and DC generators?
In alternators, the magnetic poles rotate and induce voltage into a fixed winding
107
What are the primary components of an alternator?
1. Rotor
2. Stator
3. Rectifier
4. Brush assembly
108
What is the role of the rotor in an alternator?
To create a rotating magnetic field
109
What is the configuration of the stator in most alternators?
Three-phase configuration
110
How does the rectifier in an alternator function?
Converts AC produced in the windings to DC
111
What is the purpose of the brush assembly in an alternator?
To supply current to the field coils
112
What type of control is used to manage the voltage produced by an alternator?
Varying the DC field current
113
What does an overvoltage protection system do in an alternator?
Removes the alternator from the bus during an overvoltage condition
114
What is a common troubleshooting step when an alternator fails to charge the battery?
Check for open fuses or circuit breakers
115
What are the two main problems that can prevent an alternator from producing electrical power?
1. Shorted or open diode in the rectifying circuit
2. Open circuit in the field
116
What should never be done with an alternator regarding its field?
Flash the field or polarize an alternator
117
What can damage alternators?
Excessive voltage or reverse current flow
## Footnote
Alternators should never be operated without being connected to an electrical load.
118
What should not be done with an alternator regarding its field?
Never flash the field or polarize an alternator
## Footnote
Alternators receive their field current from the aircraft bus.
119
What type of test equipment is used for alternator troubleshooting?
Specialized test equipment plugged into the aircraft electrical system
## Footnote
This equipment helps identify problems in the voltage regulator, over-voltage sensing circuit, or alternator field/output circuit.
120
What do indicator lights on test equipment indicate?
Whether a problem exists in the voltage regulator, over-voltage sensing circuit, or alternator field/output circuit
## Footnote
This helps save time and avoid unnecessary replacement of good components.
121
What is crucial to avoid burning out rectifying diodes during installation?
Connect the battery with the proper polarity
## Footnote
Ensure correct polarity is applied when connecting an external power source.
122
What is the primary electrical power source for small aircraft?
Direct current (DC)
## Footnote
DC is storable and used for starting aircraft engines.
123
Why do large aircraft use alternating current (AC) as their primary power source?
Weight savings and external power source availability
## Footnote
Large aircraft require elaborate ground service facilities for starting.
124
What is an advantage of alternating current over direct current?
Voltage is easily stepped up or down
## Footnote
AC can carry current over long distances by raising the voltage using a step-up transformer.
125
What happens to AC when it reaches its destination?
It passes through a step-down transformer where voltage is lowered
## Footnote
Current is stepped up to the value needed.
126
What type of current is required for charging batteries or operating variable speed motors?
Direct current (DC)
## Footnote
AC can be changed into DC by passing through a series of semiconductor diodes.
127
What is a benefit of converting AC to DC?
Relatively little loss in the conversion process
## Footnote
This is another advantage of AC compared to DC.
128
What are the classifications of AC alternators based on output voltage phases?
Single-phase, two-phase, three-phase, six-phase or more
## Footnote
Almost all aircraft electrical systems use three-phase alternators.
129
How is the total output voltage of a single-phase alternator determined?
By adding the AC voltages induced into each winding
## Footnote
If a stator has four windings, the total voltage is four times the voltage in one winding.
130
What is the phase difference between the voltages in a three-phase alternator?
120 degrees
## Footnote
Each winding in a three-phase alternator is spaced to achieve this phase difference.
131
What are the two types of alternators based on the type of stator and rotor used?
Revolving-armature type, revolving-field type
132
What distinguishes a revolving-field type alternator from a revolving-armature type?
It has a stationary armature winding and a rotating-field winding
## Footnote
This allows for direct connection to the load without sliding contacts.
133
What is a brushless alternator?
An AC alternator that has no current flow between brushes or slip rings
## Footnote
Brushless alternators are efficient at high altitudes.
134
What components are included in a brushless alternator?
Permanent magnetic field, exciter field, main output field
135
What is the purpose of the generator control unit (GCU) in a brushless alternator?
To monitor and regulate the main generator's output
136
How are AC alternators rated?
In volt-amps, typically expressed in kilo-volt amperes (KVA)
## Footnote
A typical Boeing 727 AC alternator is rated at 45 KVA.
137
What determines the frequency produced by an AC generator?
The number of poles and the speed of the rotor
138
What is the formula for determining AC frequency?
F = (P * N) / 120
139
What is the function of a constant-speed drive unit (CSD) in AC generators?
To maintain a uniform frequency between multiple generators
140
What is the main function of storage batteries in aircraft?
To start engines and supply power during generator failure
141
What type of battery is traditionally used in smaller aircraft?
Lead-acid battery
142
What indicates the state of charge in a lead-acid battery?
The specific gravity of the electrolyte
143
At what specific gravity is a lead-acid battery considered discharged?
Below 1.150
144
What tool is used to measure the specific gravity of a battery's electrolyte?
Hydrometer
145
What is the open-circuit voltage of a lead-acid battery per cell?
2.1 volts
146
What effect does temperature have on the specific gravity of battery electrolyte?
It affects its density, requiring correction in readings
## Footnote
A standard of 80°F is used for reference.
147
What happens to a battery's voltage when a load is placed on it?
The closed-circuit terminal voltage drops
148
What is the corrected specific gravity of the battery mentioned?
1.232
## Footnote
The specific gravity indicates the density of the electrolyte solution in a lead-acid battery.
149
What is the open-circuit voltage of a lead-acid battery per cell at a specific gravity of 1.265?
2.10 volts per cell
## Footnote
This voltage is a standard measurement for lead-acid batteries.
150
What happens to a battery's internal resistance when a load is placed on it?
It increases
## Footnote
The formation of lead sulfate during discharge causes this increase.
151
How can a battery's internal resistance be calculated?
Using Ohm's law
## Footnote
Ohm's law states that voltage equals current multiplied by resistance (E=IR).
152
What is the total no-load voltage of a lead-acid battery with 12 cells?
25.2 volts
## Footnote
This is calculated as 12 cells x 2.1 volts/cell.
153
What is capacity in the context of a battery?
The ability to produce a given amount of current for a specified time
## Footnote
Capacity is measured in ampere-hours.
154
What factors affect a battery's capacity?
1. Amount of active material
2. Plate area
3. Quantity of electrolyte
4. Temperature
## Footnote
An increase in the first three factors increases capacity, while low temperatures decrease it.
155
What is the five-hour discharge rating of a battery?
The capacity of a battery specified over five hours of discharge
## Footnote
It is determined by the number of ampere-hours a battery can provide under a certain current.
156
At what voltage per cell is a battery considered discharged?
1.2 volts per cell
## Footnote
This is a standard indicator for battery discharge.
157
What is the recommended voltage for a fully charged 12-cell lead-acid battery?
Approximately 25.2 volts
## Footnote
This is based on the open-circuit voltage of 2.1 volts per cell.
158
What is the proper procedure for checking the voltage of individual battery cells?
Measure the voltage with a VOM meter under load after verifying electrolyte level
## Footnote
A fully charged cell should read about 1.95 volts.
159
What should be done if the electrolyte level in a battery is low?
Add distilled or demineralized water
## Footnote
Acid should not be added unless it has been spilled.
160
What is the maximum charging current for a battery without manufacturer specifications?
Seven percent of the battery's ampere-hour rating
## Footnote
For example, for a 40-ampere-hour battery, the maximum current would be 2.8 amperes.
161
What is the difference between constant-current and constant-voltage charging methods?
1. Constant-current: Maintains a fixed current throughout the charge
2. Constant-voltage: Maintains a fixed voltage, allowing current to vary
## Footnote
Each method has specific applications and advantages.
162
What is a common cause for frequent servicing of a lead-acid battery's electrolyte level?
Charging voltage is too high
## Footnote
This can cause the electrolyte to boil.
163
What precautions should be taken when charging lead-acid batteries?
1. Charge in a well-ventilated area
2. Avoid sparks and open flames
3. Disconnect the negative lead first
## Footnote
These precautions help prevent explosive reactions and injuries.
164
What is the main advantage of nickel-cadmium batteries over lead-acid batteries?
Lower internal resistance
## Footnote
This allows for constant voltage until nearly fully discharged.
165
What is the effect of temperature on nickel-cadmium batteries during discharge or charging?
High temperatures are produced
## Footnote
This can lead to breakdown and other issues.
166
What is a distinct advantage of nickel-cadmium batteries?
Very low internal resistance, allowing voltage to remain constant until almost fully discharged
## Footnote
This low resistance also facilitates high charging rates without damage.
167
What danger is associated with high temperatures in nickel-cadmium batteries?
Breakdown of the cellophane-like material separating the plates, leading to short circuits
## Footnote
Increased current flow causes more heat and further breakdown of the separator material.
168
What is the process known as that can occur due to rising temperatures in nickel-cadmium batteries?
Vicious-cycling or thermal runaway
## Footnote
This process is exacerbated by the drop in internal resistance as temperature rises.
169
What materials are used to construct the positive plates of nickel-cadmium batteries?
Powdered nickel (plaque) fused to a porous nickel mesh impregnated with nickel hydroxide
## Footnote
The negative plates are similar but are impregnated with cadmium hydroxide.
170
What serves as the electrolyte in nickel-cadmium batteries?
A thirty-percent-by-weight solution of potassium hydroxide and distilled water
## Footnote
Its specific gravity is between 1.24 and 1.30 at room temperature.
171
What is the open circuit voltage range for an individual nickel-cadmium cell?
Between 1.55 and 1.80 volts
## Footnote
This varies depending on the manufacturer.
172
What chemical change occurs during the discharge of a nickel-cadmium battery?
Metallic cadmium combines with hydroxide ions, releasing electrons and converting to cadmium hydroxide
## Footnote
Hydroxide ions leave the positive plates and enter the electrolyte solution.
173
What happens during the charging process of a nickel-cadmium battery?
Oxygen is driven from cadmium oxide on the negative plate, leaving metallic cadmium
## Footnote
Nickel hydroxide on the positive plate becomes more oxidized as it accepts some of the released oxygen.
174
Fill in the blank: The negative plate controls the cell's ______ characteristics in a nickel-cadmium battery.
Voltage
175
What is one method to reduce cell imbalance in nickel-cadmium batteries?
Terminate a constant-voltage charge before full charge and complete with constant current rate
## Footnote
This technique allows the positive plates to reach full charge without excessive gas generation.
176
What is the primary hazard when servicing nickel-cadmium batteries?
The alkaline electrolyte is corrosive and can cause severe injury
## Footnote
Spills should be neutralized with vinegar or boric acid.
177
What indicates an internal short circuit in a nickel-cadmium battery?
The battery won't hold a charge
## Footnote
This can be checked for electrical leakage using a milliammeter.
178
When should the electrolyte level be checked in a nickel-cadmium battery?
Immediately after the battery is fully charged
## Footnote
This is crucial as the plates absorb electrolyte during discharge.
179
What is the normal overcharge level for a nickel-cadmium battery?
140 % of its amp-hour capacity
## Footnote
This is acceptable if the battery has been properly serviced.
180
What should be done if a cell exceeds the manufacturer-specified voltage during charging?
The cell must be replaced
## Footnote
Manufacturers specify the maximum differential between cells during charging.
181
What is the purpose of deep-cycling a nickel-cadmium battery?
To equalize the cells and correct an imbalance
## Footnote
This involves discharging it to approximately 0.2 volts per cell.
182
What is a common sign of excessive spewage in nickel-cadmium batteries?
Excessive white crystal deposits on cells
## Footnote
This occurs due to electrolyte reacting with carbon dioxide.
183
What should be done if excessive potassium carbonate is found on the cells?
Check the voltage regulator and electrolyte level, then scrub off the deposits
## Footnote
Use a nylon or nonmetallic brush for cleaning.
184
What is the recommended action if hardware shows heat or burn marks?
Clean hardware and properly torque connectors
## Footnote
Loose connections can cause overheating.
185
What does a troubleshooting chart help with when working with nickel-cadmium batteries?
Associating probable causes with corrective actions for observed conditions
## Footnote
This assists in diagnosing issues effectively.
186
What are the major parts or assemblies of a DC generator?
1. Field Frame
2. Rotating Armature
3. Commutator
4. Brush Assembly
5. Air Scoop
6. Pole Shoe
