EPS AND RES Flashcards
(142 cards)
1
Q
Batteries convert _____ energy into _____ energy
A
Chemical
Electrical
2
Q
When several cells are connected together this equals a ?
A
Battery
3
Q
The output of a battery depends on?
A
Material within
How they are connected
4
Q
Each battery cell is made of two different materials called?
A
Electrodes
5
Q
The battery electrodes are immersed in a conductive liquid called?
A
Electrolyte
6
Q
When cells are connected in series a higher _____ is achieved?
A
Voltage
7
Q
When cells are connected in parallel a higher ______ is acheived?
A
current
8
Q
Batteries are rated in ?
A
Voltage and Ampere-hours (Ah)
9
Q
Primary cell energy comes from?
A
Consuming electrodes (no re-charge)
10
Q
Secondary cells also called ____ ____ have no _________ and must be _______.
A
Storage cells
Energy at the beginning
Charged
11
Q
Large capacity rechargeable batteries are called?
A
Wet cells
12
Q
Recharging of secondary cells is done by ?
A
Passing current through in the opposite direction of discharge
13
Q
All batteries have _______?
A
Internal resistance
14
Q
Open circuit voltage is ?
A
No-load terminal voltage
15
Q
Charged battery chemical reaction
A
Lead Dioxide + Sulphuric Acid
16
Q
Discharged battery chemical reaction
A
Lead Sulphate + Lead Dioxide + Water
17
Q
The lead sulphate causes the internal resistance to increase during and when the battery is discharged, this is called?
A
Sulphation
18
Q
The amp hour spec provides a measurement of battery ?
A
Capacity or how much energy can be stored by the battery
19
Q
A dead battery voltage is considered to be ?
A
10.5V
20
Q
Another measurement of battery capacity is?
A
Reserve Capacity
21
Q
Reserve capacity is the number of ______ a battery @____C can supply a _____A load until it’s voltage drops to ______VPC
A
Minutes
20C
25A
1.75VPC
22
Q
The __________ spec provides a measurement of the starting power of a battery at -18C under a load for 30 seconds with the end voltage maintained at 1.20VPC.
A
Cold Cranking Amps
23
Q
Start batteries are manufactured with _____ plates which can convert chemical energy to electrical energy much _____ than deep cycle.
A
Softer
Faster
24
Q
Deep cycle batteries do not work well for ______ applications because they are constructed with _____ plates for lengthy discharge times.
A
Starting
Hard
25
Marine cranking amps is similiar to cold cranking amps bit is performed at a _______ instead of -18C
Warmer 0C
26
For any specific battery the MCA will be about ___% greater than the CCA.
20%
27
Separators are used between plates of lead acid batteries to prevent?
Short circuits
28
Ribs at the bottom of lead acid batteries are used to?
Catch shed material from the plates
29
List 3 types of lead acid batteries?
1. Flooded or Wet type
2. Gel cells
3. AGM (Absorbed glass mat) cells
30
Charging process
1. Run a current through the battery in the opposite direction, the chemical action is reversed
2. The plates go back to their original material and the electrolyte gets stronger
3. For a 12V battery, charging V is usually 14.2V to 14.5VDC
4. During charging, hydrogen gassing may occur through vents
31
To determine the level of charge in a battery we check the?
Specific gravity (SG) of the electrolyte
32
Specific gravity is the measure of?
The amount of acid contained in the water
33
Water has a SG of _____ and a _____ is the tool used to measure?
1.000
| Hydrometer
34
Fully charged battery SG and open circuit voltage?
1280 or 1.28 ... 12.7V open circuit
35
Fully discharged battery SG and open circuit voltage?
1150 (1.15) or less ... 11.9V open circuit
36
SG readings should be taken at ____ C
25C
37
When the temp falls we ____ our SG readings and when the temp rises we ____ our SG readings.
Decrease
| Increase
38
For each degree away from 25 we increase or decrease our SG reading by ____
0.7
39
High ambient temp battery operating specs
Reduced life and voltage
40
Low ambient temp battery operating specs?
Shelf life increases
41
The plates in a battery should always be covered with?
Electrolyte
42
When mixing electrolyte, always add ___ to the ____?
Acid to the water
43
Batteries should be cleaned with?
Baking soda and water
44
Nickel-Iron (Ni-Fe) Battery pros
Robust (virtually indestructible)
Long battery life (+30 years)
Used in mining operations
Environmentally benign
45
Nickel-Iron (Ni-Fe) Battery cons
Hard time keeping a charge
Bulky
Very expensive to make
Operates poorly in low temps
46
How to test a Nickel-iron battery?
Use a DC volt meter on cells while under load to determine state of charge (can not use hydrometer as the electrolyte density never changes)
47
Nickel-Cadmium Battery cons
Suffer from "memory effect"
| Cadmium is a disaster environmentally
48
Lithium-Ion Battery benefits
High energy density
Tiny memory effect
Low self discharge
Comes in many shapes and sizes including lightweight options
49
(Charging Terms) Initial
First charge after battery is filled with electrolyte
50
(Charging Terms) Normal
Restores battery after it has been used or sitting
51
(Charging Terms) Trickle
Maintains battery fully charged with no load connected
52
(Charging Terms) Float
Supplies charge to batteries and connected loads
53
(Charging Terms) Bulk
Restores battery after deep discharge (constant current)
54
(Charging Terms) Absorption
Ensures plates are de-sulphated after bulk (constant voltage)
55
(Charging Terms) Equalization
Elevated charge voltage to equalize cells and remove residual sulphation
56
Constant current
Outputs rated current allowing charge to build fast
Voltage increases as charge builds
Preferred method for nickel cadmium
57
Constant Voltage
Outputs preset voltage level to prevent over charging
Current decreases as charge builds
Used for "basic" charging of lead acid batteries
58
Stand alone AC PV systems include an?
Inverter
59
High quality inverters can give conversion efficiencies of ___ %
90
60
For a hybrid system what is the most common back-up?
Diesel or propane generator
61
Two mai types of grid connected PV systems?
Utility interface
| Utility Interactive
62
Utility Interface specs
Solar energy is stored in battery bank
Provides some or all of buildings electrical needs
Low batteries = building transfer to utility
63
Utility Interactive specs
No storage
| Excess energy fed to utility grid
64
What is Islanding?
The undesirable condition where a distributed generation power source such as a PV system, continues to transfer power to the utility grid during a utility outage.
65
Three factors that determine any PV modules power output?
1. Load impedance
2. Solar Irradiance
3. Cell Temperature
66
Meter bases
4-jaw: single phase
5-jaw: single phase but has 5th connection for neutral
7-jaw: 3 phase
67
Modern inverter two types?
Modified square wave
| Sine wave
68
What kind of modern inverter is seen on PV systems?
Modified square wave (cheaper than sine wave, not as efficient)
Notes: cause more harmonic distortion, sine wave inverters will cost 2 to 3 times as much but are superior
69
What is a Pyranometer?
is used to measure solar irradiance on a planar surface and is a sensor that is designed to measure the solar radiation flux density from a field of view of 180 degrees.
70
What is a Pyrheliometer?
an instrument used for direct measurement of solar irradiance
71
What three things should you check for when you first receive a new generator?
Intake sealed
Exhaust sealed
Coolant intact
72
For servicing a gen-set do not rely on the OFF button of the ATS, you should?
Remove the battery cable from the start battery (negative first)
73
Starting KVA for a motor =
Locked rotor KVA
74
"Stand by" power systems come in three forms?
Dual radial feeds
Batteries and UPS
Emergency Generators
75
Generators can be started then switched to critical loads using an?
Automatic transfer switch (ATS)
76
ATS typically take __ - __ seconds to bring "online"
8 to 15
77
Generator fuel options?
Propane - bad w/ extreme temps
Gasoline - faster start (8s) time but unstable
Diesel - most popular, slow start (12s)
78
Generator connections are typically?
Three phase, 60Hz and almost all incorporate a 4-wire grounded neutral
79
Generators should be installed?
As close as possible to main power supply
On vibration pads
Not in areas of abnormally high/low temps
With adequate fuel for outages and exercising
80
AVR =
Automatic Voltage Regulator
81
What 4 things must be the same for generators to parallel?
1. Terminal voltage
2. Frequency
3. Phase sequence
4. Phase displacement
82
Synchronized generators must have what type of protection?
Reverse Power Relays (RPR)
83
Generators should be run for at least ___ minutes/week and is preferred to do so under __% load
30mins
| 40% load, full if possible
84
What does exercising a generator accomplish? (6 things)
1. Booster charge to the batteries
2. Cleans carb sediment
3. Keeps all parts lubed
4. Brings engine up to operating temp
5. Removes any condensation from crankcase
6. Restores residual magnetism
85
During the exercising period of a gen, observe and record?
```
Oil pressure
Battery charging ammeter
Fuel level
Voltage and current levels
Frequency under load
Crank time
```
86
Transfer switches are ____ before _____
Break before make
87
The purpose of a transfer switch is to?
Switch the load from normal supply to emergency power either manually or automatically
88
What type of transfer switch would be used when a load could be affected by a slight bump in the line when transferring power?
Closed transition transfer switch (CTTS)
89
Typically a PV cell has an efficiency of?
20% or less (converted into electrical energy)
90
When paralleling generators if the lights are flashing out of sync what does this indicate and how is it rectified?
Wrong phase sequence
| Interchange 2 leads of incoming alternator or change direction of prime mover
91
When paralleling generators if the lights are flashing at the same time but very fast what does this indicate and how is it rectified?
```
Incorrect frequency (too low).
Changing the primer mover speed (DC motor excitation)
```
92
When paralleling generators if the lights stay on dim to bright what does this indicate and how is it rectified?
Phase displacement off.
| Tweak the excitation of the primer mover to change the position within the revolution.
93
When paralleling generators and they lights are fully on bright or dim what does this indicate and how is it rectified?
Voltage does not match.
| Adjust the field excitation of the alternator
94
Paralleled alternators share KW by varying the ______ and share KVARS by varying the _______?
Power of the prime mover
| Field excitation of the alternator
95
What is "hunting"
Surging or oscillating of power between 2 alternators
96
How can "hunting" be rectified?
1. "Damping" the governor
2. Heavy fly wheels
3. Amortisseur windings
97
The difference between a primary cell and a secondary cell is?
Secondary cell is rechargeable, primary is not
98
To determine the state of charge for a lead acid battery, could use a?
Voltmeter with a load connected to the battery
99
The no-load terminal voltage of a fully-charged, 6 cell lead acid battery would measure as?
13.2V
100
The internal resistance of a storage battery will _______ during charging?
Decrease
101
"Sulfation" is most likely caused by?
too low of water level
102
What type of genset is usually used with microhydro and wind power?
Asynchronous
103
Pressure x volume power lost at a PRV can be recovered by replacing the valves with a ?
Pump as a Turbine (PAT)
104
A _______ is essential for disconnecting the turbine in the event of loss of grid or phase (hydropower)
Intelligent relay
105
Advantages of hydro kinetic power?
1. More predictable output than wind power
2. No retaining structure
3. Discreet or invisible due to the turbine components near total immersion
106
Disadvantage of hydro kinetic power?
Winter operations problematic
107
3 Main types of hydro kinetic turbines?
1. Vertical axis
2. Horizontal axis
3. Oscillating-foil
108
5 types of renewable energy?
```
Sunlight
Wind
Hydro
Tides
Geothermal heat
```
109
A wind turbine is a rotating device used to convert?
Kinetic energy into electrical energy
110
2 types of wind turbines?
Horizontal axis
| Vertical axis
111
The electrical machine of a wind power source is basically a ?
SCIM
112
A doubly fed induction machine is basically a ?
WRIM
113
A doubly fed induction generator has very good?
Efficiency
114
What strategies are employed to extract maximum power from the wind?
Blade pitch control
Variable pulley drive
Doubly fed induction generator
115
The nacelle is equipped with two devices to keep account of its angular position?
A turn counter
| A limit detector
116
What is the purpose of an accumulator?
Store energy and be can used to supplement and regularize the flow rate of a pump
117
Wind power brake systems?
Rotor brake = hydraulic released, spring applied
| Yaw brake - hydraulic applied, spring released
118
What does an Anemometer do?
Wind speed monitor
119
What are the 2 purposes of a UPS?
1. An electrical apparatus that supplies emergency power to a load when the input power source or mains power fails.
2. Enhance the quality of regular power by providing surge suppression and filtering noise
120
Off-line UPS specs
UPS is in "stand by"
Inverter not in primary path to the load normally
Time delay in the switching operation (2-12msec)
Very inexpensive
121
On-line UPS specs
- Batteries always connected to inverter = no power transfer switch.
- Charger/converter larger
- Units larger and generate more heat
- Shorter lifespan for unit and batteries
122
What is the simplest and most economical UPS?
On line UPS with no bypass
123
Ferro-Resonant UPS specs
- Same as off-line but when AC fails a special detector circuit switches inverter on and opens transfer switch
- This transformer essentially holds energy long enough to cover transfer time = eliminates it
- Transformer filters output
- Limited to 15KVA
124
Line interactive UPS specs
- Power is normally taken from utility with more active filtering for better waveform output
- Similar to off-line but utility power fed through tap-changer
- Tolerates continuous under voltage brown outs and over voltage surges without consuming battery reserve
125
Rotary UPS specs
- Uses high inertia of flywheel provide short term power in event of power loss (15-40sec) until generator picks it up
126
Rotary UPS advantages?
- High current output
- Long lasting (30 + years)
- Provide PF correction
127
Rotary UPS disadvantages?
- Expensive and much larger
- Maintenance required and extensive
- Can not be hot swapped
128
All UPS provide protection from surges, spikes and noise using a ?
Metal Oxide Varistor (MOV)
129
Second line of defence for a UPS?
Static bypass switch
130
Good field practice is to ______ bypass the UPS first then _____ bypass
Internal
| External
131
Internal resistance of a battery increases due to?
Sulphation
132
What batteries are pressurized?
AGM and sealed lead acid
133
A fully charged lead acid battery has ___ V per cell and a hydrometer would measure ____ specific gravity and would freeze around ____ C
2.2V
1280
-60C
134
A lower depth of charge battery means the battery is ____ charged?
More
135
Which battery rating gives the best indication of how much energy it stores?
Amp-hours
136
After maintenance, the battery charger should be set to?
Equalization
137
The charging state where the battery is at a voltage where it will have the longest lifespan is?
Float/trickle
138
2 timed stages when normal power is restored?
1. Ensure NP is returned to stay
| 2. Engine cool down
139
When is the electrical brake solenoid on the transfer switch on?
Only during load transfer
140
Another device used for synchronizing alternators which uses a single needle indicator influenced from a coil connected to each alternator is called?
Synchroscope
141
What is home portable generators commonly referred to as?
Back up power
142
What is the difference between a "nonseparately derived system" and a "separately derived system"?
The neutral is disconnected by the transfer switch on a separately derived system and must be re grounded.
