Objective: 1a Flashcards
(165 cards)
0
Q
The magnetic field can be created with either _____ _____, or more commonly, _____.
A
Permanent Magnets,
Electromagnets
1
Q
The rotor portion of the alternator assembly provides what?
A
Provides the main rotating magnetic field, one requirement of magnetic induction
2
Q
Where are the field coils found and what do they need to retain in a self-excited system?
A
The field coils are found in the Exciter. The exciter needs to retain a Residual Magnetism in the self-excited system.
3
Q
What sets the reference voltage in a voltage regulator?
A
Voltage adjust control
4
Q
What is the purpose of the ATS (Automatic Transfer Switch)?
A
To furnish an alternate source of power to mission critical facilities where a loss of power may result in mission failure.
5
Q
What do you need to do for manual operation of the ATS (Automatic Transfer Switch)?
A
Use the two manual handles and using the following procedures:
1. Open the cabinet door of the Transfer switch.
2. Place the motor disconnect switch (S1) to the “OFF” position.
3. Transfer to emergency
a. Pull upper manual handle down.
b. Push lower manual handle down.
4. Retransfer to normal
a. Pull lower manual handle up.
b. Push upper manual handle up.
6
Q
What is stationary in the alternator?
A
Stator
7
Q
How many voltage values are in a Wye connection?
A
There are 2 voltage values; Phase Voltage and Line Voltage.
8
Q
A Wye connection is connected in _____?
A
parallel
9
Q
A Delta connection is connected in _____?
A
series
10
Q
What form transfers with the generator if it is moved to a different location/base?
A
AF Form 719
11
Q
What are the three requirements for AC generation?
A
(1) Magnetic Field
(2) A conductor
(3) Relative motion between the conductor and field
12
Q
These requirements fall under the Principle of what?
A
Magnetic Induction
13
Q
Transformers use the Principle of what?
A
Mutual Induction
14
Q
Current transformers can be step up or step down? TRUE OR FALSE?
A
False, Potential Transformer is a step up or step down.
The Current Transformer is always a step down, so voltage is dangerously high
15
Q
Potential transformers can be step up or step down? TRUE OR FALSE?
A
True, the Potential Transformer is a step up or step down
16
Q
What types of transformers are used for the AC AMMETER?
A
Current Transformer
17
Q
What types of transformers are used for the AC VOLTMETER?
A
Potential Transformer
18
Q
What does the WATTMETER indicate?
A
True Power load in an AC circuit
19
Q
What does the Power Factor meter indicate? (it indicates two things)
A
Purely Resistive Load and indicates the percentage of true power being used
20
Q
What is APPARENT/TRUE/REACTIVE POWER?
A
APPARENT POWER – power produced at the Power Source, which is the Generator.
TRUE POWER – consumed by the resistive load or loads.
REACTIVE POWER – power consumed by the reactive load devices in a circuit.
21
Q
A three phase alternator has how many sets of windings and they are separated by how many degrees?
A
It has 3 windings in the Stator, the windings are positioned 120° from each other. 120° is the phase angle.
22
Q
What is used with the AC Ammeter and Voltmeter to a change connections between phases?
A
Selector Switch
23
Q
When is there no voltage present on the sine wave?
A
0°, 180°, and 360°
24
What is commonly referred to as the DC generator?
Exciter
25
What provides relative motion?
Prime Mover
26
What converts AC to DC in the alternator assembly?
6 Silicon Diodes and a Rectifier Circuit
27
What kind of voltage does the MPU create?
Pulsating AC
28
In order to initiate a test of the ATS, what must the RUN/STOP/REMOTE switch be in?
REMOTE
29
What is peak performance?
Voltage and Frequency
30
When is the highest operating temperature recorded on the AFCESA 487?
After 15 minutes
31
What switch is used to initiate a test on the ATS?
STOP SWITCH
32
What provides phase shift to drive linear motion?
Capacitor
33
How do you measure phase voltage?
Between any phase and the neutral.
34
How do you measure line voltage?
Between any two phases
35
On the ATS you must verify the settings have not been changed, the settings to check include: _____, _____, _____ and _____ _____.
Start Delay, Transfer Delay, Retransfer Delay, and Stop Delay
36
The solid-state panel delay settings can be adjusted by what?
Inserting a small screwdriver in the slot and rotating clockwise to increase the time delay or counter-clockwise to decrease the delay.
37
The _____ - load test is used to test all functions of a panel except the actual transfer of load.
with out
38
The _____ - load test will also test all functions, but will also include a load transfer.
with
39
When you perform a pre-optional inspection of the standby generator set. Ensure engine Control Switch is in the what?
“REMOTE” or “AUTOMATIC” position
40
Open ATS door, move the Test Mode switch to the “_____” position on the _____ _____ module.
“WITH OUT – LOAD”; Power Sentry
41
Close ATS door and _____ the _____ switch.
locate; test
42
Rotate the _____ / _____ / _____ switch to the “_____”.
Test / Normal / Retransfer ; “Test Position”
43
After brief delay (_____), generator starts.
(3 – 5 seconds)
44
After observation of LEDs on Power Sentry, while turning the switch to the “Test” position what happens next?
The Source 1 LED will go out. After a short delay, the Start Gen Set LED will come on and the generator will start.
45
Once generator has started and its _____ and _____ are within limits, Source 2 LED will illuminate.
voltage and frequency
46
After the transfer timing LED illuminates the time delay setting is met at which time the transfer complete LED comes on indicating what?
Indicating a transfer signal would have been sent to the transfer motor.
47
After test, return the _____ / _____ / _____ switch to the “_____”position.
Test / Normal / Retransfer; “Normal”
48
ATS will monitor what?
ATS monitors Source 1 for proper voltage and frequency
49
The battery charger should be operating at a low _____ _____ with a battery that is fully charged.
charging rate
50
Many charges are equipped with an “_____” switch and protected by a _____.
“ON / OFF” ; fuse
51
What is housed in the stator?
Stationary conductors of the alternator
52
What are the conductors also referred to as?
Stator windings
53
The stator can be constructed to provide _____ or _____.
Single Phase or Three Phase
54
What degree are the windings in three phase?
120°
55
Damper windings combat voltage fluctuation caused by what?
The rotor speed
56
What slows down the rotor?
Damper windings magnetic field by adding counter-torque to the stator
57
What happens when the rotor tries to slow down?
The Damper Windings magnetic field shift to add to the torque of the rotor field
58
Rotating rectifier circuits change AC to DC by use of what?
Six Diodes
59
What type of rectifier is the six diodes connected to?
Full-wave rectifier
60
What is an exciter often referred to as?
DC Generator
61
How is the varistor connected with the rectifier output?
In parallel with the rectifier output
62
What does a surge suppressor suppress?
Peak voltage surges
63
How does a varistor suppress volts?
Decrease its resistance and conduct more current through itself, suppressing the voltage surge
64
Variator and Surge Supressor are what?
The same thing
65
What provides the mechanical energy (torque) to turn the alternator rotor shaft?
Prime Mover
66
What begins to produce AC Voltage when the prime mover turns?
Exciter
67
What senses the voltage at the output terminal of the stators?
Voltage Regulator
68
What senses the voltage at the output terminal of the stators?
Amount of current flowing through the exciter field coils
69
What is the purpose of an Exciter?
Provide a constant source of Direct Current to energize the alternators magnetic field
70
What are the components of the Exciter?
Field Housing, Armature, and Rectifier Circuit
71
What are the brushes used for?
Provides the electrical connection between the rotating component
72
What are the brushes made of?
Soft carbon
73
What is the FIRST step when inspecting an alternators components?
Make sure the unit is off-line and disconnect from any other power source.
74
What is the LAST step when inspecting an alternators components?
Make sure residual voltage in the rotor, stator and exciter is discharged.
75
What is the FIRST step when inspecting a rotating rectifier?
Remove the diode lead, this step will require the lead to be de-soldered from the diode.
76
When inspecting a rotating rectifier, what is the LAST step?
Re-install serviceable diodes by positioning diodes on the heat-sink, secure, re-solder, and replace.
77
What is the first step in inspecting a surge suppressor?
Remove exciter end cover
78
What is the last step when inspecting a surge suppressor?
Observe the resistance value
79
What resistance value should the varistor have?
15,000 ohms or greater
80
An alternator converts _____ energy into _____ energy using the principle of magnetic induction to produce voltage.
mechanical ; electrical
81
The exciter assembly is inspected for what conditions?
Inspect exciter assembly for missing or broken hardware
82
What must a replacement diode have to be considered compatible?
Must have the same electrical rating as the original to be compatible
83
How is the lead removed from the diode terminal?
Soldering iron, de-solder and remove
84
How is the diode secured to the heat sink during installation?
Attach a nut
85
What type of meter is used to test diodes?
ohmmeter
86
What does a low reading in a diode mean?
The diode has a short
87
What does a high reading in a diode mean?
open or O.L.
88
What is used to check the insulation resistance of the generator’s main stator winding?
Megometer
89
The rotor portion of the alternator assembly provides what?
Provides the main rotation magnetic field, one requirement of magnetic induction
90
The magnetic field can be created with either _____ _____, or more commonly _____.
Permanent magnets ; electromagnets
91
An electromagnet is what?
A coil of wire wrapped around a core material
92
What is the purpose of alternators?
Converts mechanical energy to electrical energy
93
What principle do alternators use?
The principle of Magnetic Induction: to produce voltage
94
What portion of the alternator assembly provides the main rotating magnetic field, which is a requirement of magnetic induction?
rotor
95
What is commonly referred to as a DC generator?
exciter
96
In the event the rotor tries to slow down, the ____ _____ magnetic field shifts to add to the torque of the rotor field, keeping rotor speed.
Damper windings
97
What controls the amount of voltage when using induction?
Strength of the magnetic field, number of conductors cutting the field and the speed of relative motion
98
What is true power?
Power consumed by the resistive load
99
What is apparent power?
Power produced at the power source
100
What is reactive power?
Power consumed by the reactive load devices
101
What is factor power?
The percentage of apparent power being used as true power by way of the resistive loan in an AC circuit.
102
What are the types of connection for an alternator?
Delta (series) and Wye or Star (parallel)
103
What is DELTA connection used for?
Industrial loads
104
What is WYE connection used for?
For low power circuits
105
What portion of the alternator provides the main rotating magnetic field?
rotor
106
What kind of magnets does the rotor have?
Permanent magnet and electromagnets
107
What is the common type magnet?
Electromagnets
108
How many magnetic poles can an alternator rotor have?
Two, four, six or more magnetic poles
109
What are some common examples of prime movers?
Gas or diesel engines, turbine engines, waterwheels, windmills, etc.
110
A serviceable varistor will have a resistance value of ____ ohms or greater.
15,000
111
Rotating rectifier circuits change AC to DC by the use of ____ ____ .
Six silicon diodes. The three-phase AC output of the rotating armature is rectified to DC by the use of six silicon diodes.
112
What is housed in the stator?
The stator houses the stationary conductors.
113
What makes up 1 magnetic field?
North and South Pole
114
What sets the reference voltage in the control unit of the electronic governor?
The frequency-adjusting rheostat
115
How do you initiate a test in the ATS (Automatic Transfer Switch)?
Turn off the S1 switch
116
What are the 3 inspections within a pre-operational inspection?
Safety, Equipment, and Pre-operational setup of controls
117
What form is maintained for life of the unit?
AF Form 719
118
Where would you put a continuation of remarks on an AFCESA 487?
back of form in the comments/remarks section
119
Why would you not disconnect the secondary of a current transformer if it is energized?
you don't break connections when there is current
120
Anything to do with wiring we check for? Anything to do with connections we check for?
(C.D.O.F.) Cracks, Deterioration, Over-heating, Fraying ; Security, Corrosion
121
What prevents both contacts from being closed at the same time in an ATS?
Mechanical Interlock
122
Who files the AFCESA 487 after it has been accomplished?
supervisor
123
What five conditions is there, that would start the transfer of power in the ATS?
1. Over voltage
2. Under voltage
3. Over speed/ frequency
4. Under speed/ frequency
5. Complete power loss
124
What are the different time delays in an ATS and what are they for?
Start- allows the generator to warm up
Transfer- switches power source to generator
Re-Transfer - allows original power source to warm up
Stop - engine cool down
125
If a battery charger is installed you inspect for it to be operable it should be charging at a ______.
low rate
126
What does a Frequency meter indicate?
the number of cycles per second that are being completed
127
The AC Voltmeter indicates what type of AC Voltage?
Effective Voltage
128
The number of turns is referred to as the _____.
turn ratio
129
If there are more windings or turns in the primary of a potential transformer and less in the secondary, then this is what type of potential transformer?
step down
130
What is the purpose of the Alternator? (two answers)
Converts mechanical energy into electrical energy
Produces Alternating Current (AC)
131
Speed is directly proportional to what?
frequency
132
What must be removed first with all inspections dealing with the exciter?
disconnect batteries to prevent accidental starting
133
Mechanical rectification utilizes what?
brushes and seal rings
134
Brushless exciters use what to convert AC to DC?
rectifier
135
What provides full load current to the customer?
stator windings
136
What combats voltage fluctuations?
damper windings
137
How do you test a diode and what indicates a good or bad diode?
ohmmeter
High resistance in both directions the rectifier is open - bad diode
Low resistance in both directions the rectifier is short - bad diode
High resistance and Low resistance in both directions of the rectifier is closed - good diode
138
How do you replace a diode?
a. De-solder connection leads
b. remove the nut
c. lift diode from the heat sink
d. Reinstall serviceable diodes by positioning diodes on the heat sink, securing attaching nuts, and resoldering diode leads. Replace unserviceable diodes.
139
How do you test a fuse in an energized circuit and what indication on the multimeter if bad/satisfactory?
a. Set the meter for volts AC/DC depending on circuit voltage
b. Measure across the fuse
c. Measure with voltmeter checking for a difference of potential (what goes in one side of the wire, should come out the other side
If the voltmeter shows any kind of number that is bad
0 volts = satisfactory
140
When inspecting alternator components, what items MUST be discharged?
residual batteries, capacitors, and windings
141
What are the five contaminants that can affect the insulation material of your windings?
1. Dirt
2. Salt
3. Grease
4. Oil film
5. Moisture should not be allowed to accumulate on the windings
142
When do you record the reading in a 30/60 time resistance test?
Record the 60-second reading
143
What is a speed sensitive device used to regulate the engine speed from idle to maximum rated full-load speed?
electronic governor
144
Define Isochronus or Zero Droop
allows the engine to remain at constant speed, regardless of load charges, for a single or paralleled unit.
145
Define Droop
change in speed with a change in load
146
When replacing a control unit, what adjustments must be made?
intial adjustments and final adjustments
147
What is the special inspection item when dealing with the governor actuator?
linkage for freedom of movement
148
What is the special inspection item when dealing with the voltage regulator?
vibration isolation dampers
Inspect for cleanliness
149
When replacing an MPU, how many turns must you back it off once it has touched the top of the flywheel tooth?
one
150
What repositions the fuel rack accordingly?
actuator
151
What are the input and output connections on the control unit?
Magnetic Pickup
DC battery
152
What is the first thing you do if there is a malfunction of the generator?
move the start switch to the "STOP" position
153
If all else fails, one could cut off the air supply. How is this done?
clipboard, rags, in the air intake. anything but your hand
154
If load increases, what will happen to your voltage being created at the MPU? Would a higher or lower output voltage be given to the governor actuator in order to regulate the speed?
actuator voltage remains at a higher level
155
What do each of the indicator lamps on the ATS cabinet door represent in regards to what is happening within the ATS?
tells you how the load is connected
tells you what's connected (Emergency or Commercial)
156
What is the brain component of the ATS?
Power Sentry Control
157
Why do we need to test our indicator lamps on our control panel of the generator?
incase there is a fault and the indicator lamps go on.
If there is a fault the indicator lamps will go on
158
What switch is used to initiate a test on the ATS?
RUN/STOP/REMOTE SWITCH
159
What does the with-load test switch test?
it test all functions, but will also include a load transfer
160
2 wire/ 3 wire… what’s the difference?
2 wire - water
3 wire - air
161
What makes or breaks current flow in your ATS?
contact assemblies
162
What five conditions is there, that would start the transfer of power in the ATS?
1. Over voltage
2. Under voltage
3. Over speed
4. Under speed
5. Complete power loss
163
What position should the S1 Motor Disconnect Switch be in after manual operation?
"Automatic" position
164
What do you look for with the values given to indicate whether or not to use a three phase formula or a single phase formula?
Amperage (3 amperage values for a 3 phase; 1 for a single phase)
