Pls 220 Flashcards
the full load current, or full load amp rating of any electric motor is the ______________________ it can safely draw from the line
max amt of current
where to find FLC rating on a motor
name plate
what table in the CEC is used to determine motors FLC
table 45
how to find minimum code conductor ampacity and from what code rule
- multiply FLC by 125%
-CEC 28-106
What table to find trade size conductors
T 1,2,3,4……
what code rule to find temperature limitations for conductors
CEC 4-006
Can trade size conductors be smaller then CEC calculated conductor ampacity
NO
Every electric motor and its branch cct require a ______________ means and some sort of __________ protection
-diconnecting
-overcurrent
What are type P fuses
non time delay
what are type D fuses
time delay
what are the 3 types of overcurrent devices
-type P fuses (non time delay)
type D (time delay)
-cct breakers
Why do motors create a surge when the electric motor starts
-large inrush current needed to start the electric motor
What code rule and table is used to size overcurrent devices
-CEC 28-200
-Table 29
What are standard trade sizes for saftey switches
30,60,100,200,400,600A
In non-fused switches the ampere rating of the load determines the _____________ size
disconnect switches
In fused diconnects, the ampere rating of the chosen fuse determines the ___________________ size
disconnect switch
What are bonding conductors used for
bond to ground the non-current carrying metal parts of the electric motors branch cct
What section of the CEC indicates about bonding and what table
section 10
- 10-616 1)
-Table 16
does the bonding conductor need to be larger then the supply conductor
no
What CEC section is used for overloads
26-306
A motor drawing more current than its FLC is ______________
overloaded
What happens if a motor is overloaded
-motor overheats
-burn out motor windings
What is the purpose of the overload device
-shut down the motor before its windings are destroyed
overload devices operate on a _______________ baisis
time-lags
what must seperate over load devices do
monitor and respond to motors current (proportional to winding temp) to shut down the motor
the bigger the over load the _____________ the overloaf device _________
-quicker
-opens
What are the types of overload devices
-bimetallic
-solder
-electronic
The max current rating of a seperate overload device is dependent on what 2 things
-Full load cuurent
-service factor
without a service factor must have overload protection calculated based on what code rules
115% of FLC (28-306)
140% of FLC (28-710) for hermetic motors using O/L relays
Describe the operating principals of a thermal overcurrent protecting device
-current sensitive material’
-in series with the motor
-heats ip and heat sensor trips
What are the advantages of electronic overloads compared to fixed thermal overloads
-can be dialed to specific trip setting
What name is assigned to the device which protects an electric motor burning out?
-overload
What is the service factor percentage multiplier for a SF of 1.15 or greater
125%
What is the service factor percentage multiplier for a SF of less than 1.15
115%
What is the service factor percentage multiplier for a hermetic motor proteccted by a overload relay
140%
For Schools/hotels/hospitals what code section do you go to
Section 8
What do hydroelectric dams use
a resivoir
How do large power utility wind terbines work
-use generators that produce AC b/c easier to connect the output to the transmission line.
What type of current do smaller wind terbines use
DC
what do wind terbine breaks do
-prevents wind terbine from rotating if the wind speeds are too great
What must be opened to completley de-energize the panelboards branch cct compartment
-utility diconnect switch
-diconnect switch
-BOTH!!!!!!!
whats the most common way of producing electricity from the sun
photovoltaic cells
light is made of particles called ________________
photons
examples of renewable energy sources
-solar
-wind
-hydro power
-geothermal
2 methods used for hydropower electrical generation? advatage and disadvantage of each
- resivoir: D, alters body of water. a, allows water to be held for later power generation
- gates: A, can increase/decrease water flow. D, excess water from run off
what is the puirpose of the gearbox and break in wind terbine
prevents wind terbine from rotating if winds are too high
what is the purpose of a silicon solar cell
produces potential difference
What is a solar cell
-individual source of energy
what is a solar module
-a panel that has many cells connected together to increase the output voltage and current capacity
what is the solar array
many solar modules connected together to increase the voltage and current capacity
what type of battery technology is used for most renewable energy storage systems?
lead-acid
What function does the charge controller serve in a battery storage system?
-prevents batteries from being damaged from over charging
-done by limiting current and voltage of battery
what are stand alone solar systems
-not connected to the power grid or use a back-up generator must have enough capacity to supply max exited load
the amount of power required to be supplied by the stand alone solar system deoends on what
electrical load connected to the system
for solar systems what is the total watt-hours/day multiplied by to compensate for all the systems innefficiencies
multiply by 1.25
The size of a battery bank for solar _____________ the more times its completley discharged
decreases
What is an AC module
-A complete emviromentally protected assembly of interconnected solar cells
-generates AC power from sunlight
What is an array
-assembly of photovolataic modules with a support structure and foundation,tracking and other things required to form a power-producing unit
What is a bipolar system
-a solar photovolataic system with 2 monopole photovoltaic source or output ccts has an opposite polarity to a common refrence point or centre tap
What is a charge controller
-equipment controlling DC voltage or current or both
-charges a battery or other storage device
whats an interactive system
-a power production system that operates in //
-can deliver power to another system such as a supply authority system
whats an inverter-combination inverter/power conditioning unit
-used to invert DC into AC at a fixed voltage and frequency in a stand-alone system or following wave form in a utility interactive system
whats a power conditioning unit
-used to change voltage level or waveform or alternating or regulate a power sources output
what is a utility-interactive inverter
-used in // with an electric utility and uses prevailing line voltage frequency on the utility line as control preamiter
-ensuring that the renewable energy systems output is fully synchronised with the utility power
what is a monopole
-an array or portion of an array with 2 source cct conductors
-one + and one -
what is a nacelle
-the body,shell, and casing covering the gearbox, generator, blade hub and other parts mounted on the top of a tower structer of a propeller-type wind terbine and electronically connected to the rest of the wind terbine generator electrical system after instillation
what is a photovoltaic combiner
-an assembly of buses and connections that may have over current devices,control apparatuses, switches or others connected to a photovolatic source cct or outputs of other combiners to create an output at higher current or voltage or both
what is a photovoltaic module
-a complete, enviromentally protected asssembly of interconnected solar cells
what is a photovoltaic output cct
-cct conductors between the photovoltaic source ccts and the power conditioning unit or DC utilization equipment
what is a point of common coupling
-point where the supply authoritys system is connected to the power producers facilities or conductors
what is rated power on a small wind turbine
-max power output at a wind speed of 11m/s or less
what is renewable energy
-energy from resources that are naturally replenished
-like sun,wind,water
what is a solar cell
-the basic photovoltaic device that generates electricity when exposed to light
what is a solar photovoltaic system
-all the comonents and subsystems that convert solar energy into electrical energy sutible for connection to a utlization load
what is a stand-alone system
-system that supplies power independantly of a supply authorys network
what is a supply conductor
-conductor used to connect the system to its electrical point of delivery
what is a tower for wind terbines
-a pole or other structure that supports a wind turbine
what is a wind-large wind system
-system that has 1 or more wind turbines
-rated power output exceeds 100kW
what is a small wind system
-system that has one or more wind turbines with a rated output up to and including 100kW
what is a wind turbine
-mechanical equipment that converts wind kinetic energy into electrical energy
what is the wind turbine generator
-all electrical equipment and ccts within the wind turbine structure to the point of coupling to the load or grid
what code section do you find renewable energy
section 64
the sum of the current ratings of overcurrent devices in ccts supplying power to a busbar or conductor can exceed bus bar or current rating by a max of ____________% in non residential. what code rule for non residential to find this
120%
-64-112(4c)
in residential the supplying power to a busbar or conductor can exceed busbar conductor rating to a max of _______________%
125%
what is corrosion
an electrochemical reaction where metals oxidize
when do metals corrode
-when they are in the presence of an oxidizing agent
what is the most common oxidising agent
oxygen
an atom ____________ an electrical charge when it contains the same number of electrons and protons
does not have
when an atom loses one or more electrons it becomes __________
positibve because has more positibe protons
oxidisation occurs when an atom _____________ one or more electrons
loses
What 2 things are needed for corrosion to occur
- oxidising agent
2.reducing agent
the more _____________ the reduction potential, the less likely the element is to oxidize
positive
the more _______ the reduction potential, the more likely the element will oxidise
negative
what are 2 types of corrosion
1.standard corrosion, in a single type of material
2. galvanic corrosion, caused by joining 2 dissimilar metals together
for standard corosion what does the small potential difference cause
-allow current to flow from a more negative area to a more positive area in the piece of iron
what is commonly used to protect steel
zinc, done by applying a thin coating of zinc over the steel
what happens when zinc corrodes
-creates a protective coating of zinc oxide which prevents water molecules from reaching the zinc and iron in the steel.
what is steel with zinc coating called
galvinized steel
when does galvinized corrosioon occur
-when 2 dissimilar metals are connected in the presence of an electrolyte like water
-the metal with the lower reduction potential oxidizes, giving up its electrons to the other material with the higher reduction potential
What enchances corrosion
-electrolytes
-acids
-temperatures
an ______________ in temperature causes an increase in corrosion
increase
corrosion rate doubles for every ___________ in temperature
10 degrees celcius increase
What is corrosion
electrochemical reaction where metals oxidize
what are the terms oxidization and reaction occurs
-oxidization- happens when an atom loses one or more electrons rusts with water and oxygen
-reduction- happens when electrons positive charge is reduced
What happens if steel bolts are used to hold 2 peices of copper together? what is the name for this corrosion
-Galivanic corrosion
-2 dissimilar metals are connected in the presence of an electrolyte
whats the electrochemical reaction when iron rusts?
-when are an atom loses 1 or more electron chemical that recieves electrons is being reduced, loss of electrons cause corrosion
What is galvanized steel
-steel with zinc coating
What are 3 things that accelerate the corrosion process?
-higher temp
-acids
-electrolytes
-lower PH level water (more acidic)
Cathodic protection is a method that _________________ the corrosion of metals
prevents
What are the 2 parts to a cathodic protection system
-anode
-cathode
what is an anode
-the peice of metal that loses electrons
What is a cathode
-the piece of metal that recieves the electrons
what is the galvanic cathodic protection
-uses sacraficial anodes
-no power supply
What is impressed currrent cathodic protection
-uses DC power supply
-uses anodes
An anodes usuable life is determined by what
-anodes mass and material
-size od structor being protected
-conditions (moisture,salt, acidic levels, temperature)
Larger anodes take _______________ to corrode and have a _____________ lifespan
-longer
-longer
an anodes chemical material determines how much _________________ is supplied to the protected structure
current
the more current an anode supplies the ______________________ it takes to currode
faster
An anodes life span ______________________ if more of them share the responsibility of protecting the structute
increases
Advantages of galvinized cathodic protection
-no need for power supply
-less cost
-little or no matience other then periodic replacement
disadvantages of galvinized cathodic protection
-low current output
-hard to test
-shorter anode life
-no power switch
-might not protect structure if grounded with copper conductors
impressed current cathodic protection is used where _________________ current is required to protect a structure
more
most impressed current anodes have a _______________ lifespan when compared to sacraficial anodes.
longer
Where is an impressed current system usually installed
-poorly coated, very large or bare metal structures
What to impressed current systems use
-DC power supply
For an impressed current system the _____________ output of the supply is connected to the structure and the _______________ output is connected to the anodes
-negatove
-positive
what does a recifier do in an impressed current system and how does it work.
-pulls electrons from anode and pushes them into the cathode
-structure still loses electrons but cant corrode because there are alwasys electrons flowing to the structure
an anode in an impressed current system ________________ the structure and eliminates any potential differences inside the metal
polirizes
___________ current is required when the anodes are closer to the object but more are required to light the object
less
Anodes for galvinized cathodic protection for a land bases structure are usually made from what and why
-magnesium
-allows higher current to protect structure
impressed current anodes are dicided into 2 categories
- conventional anodes
2.precious metal anodes
what are the 2 types of conventional anodes
- graphite
2.high silicon cast iron
precious metal anodes are what material
- platnium
- mixed metal oxide
What does the consumption rate determine on anodes
- how much mass is lost at the anode per uear based on the amount of current needed to protect the structure
The max current density is the ___________________________ that sould be supplied by the anoded based on its surface area
max current
Aditional ___________ is placed berween the canister and the ground to reduce resistance on impressed current systems
coke breeze
What are magnesium anodes used for and what are their attributes
- galvanic cathodic protection
-installed in a sack filled with gypsum/bentonite backfill
-backfill retains moisture
-provides a constant enviroment for the anode
__________________ are where one or more anodes are installed. What are the 3 configurations
- Ground beds
1. remote
2.descreet
3. linear anodes
When are remote anodes used
-protect a large area and only used with impressed current cathodic protection
-100-500+ ft deep
- 8-75amps
disadvantage of remote anodes
- anodes very deep in ground
-expensive to drill to install
what is a descreet ground bed
-anodes installed 5-10 feet from the structure that is being protected
-5 to 10 feet below grade
-10-30 feet from centre to centre
-used for galvanic or impressed current vathodic protection
-more common for smaller structures
what is linear anode systems
-uses one continuous anode thats located within 4 ft of the structure
-common in pipelines
-provides the most even protection
-requires the lowest power output
-easy to install
3 main factors that accelerate the normal rate of corrosion
- electrolytes strenght
- acidic content
- ambient temp
Drier soil has higher resistance then wet. theirfore it requires ____________ voltage to produce the same amt of current
more
What formula to use to calculate the expected life of an anode
Weight x utilization factor divided by output x utlization factor
the utlization factor is commonly ______________
80%
consumption rate is rated in _____________
pound/amp year
does mixed metal oxide or high silicon cast iron anodes last longer
mixed metal oxide
Testing cathodic protection is carried out _____________
monthly
____________ are used with the meter probes and only use one hand to reduce the chance of electrical shock
clips
What are the causes for no output voltage from the rectifier
-Rectifier fuse is broken
-switch is off
-cct breaker at the panel is off/tripped
-transformer on rectifier cct is defective
on a rectifier where is the built in ammeter located
-front of the rectifer
NACE considers a structure to be protected from corrosion when it has a minimum of ______________ “instant off” reading or a ______________ from its “native” voltage
-850mV
-100mV
The analog meter installed on the cathodic protection rectifier are reading 0 amps and 25-volts DC.
a) is the strucutre protected
b) what would be a reason for the ammeter to read 0 amps
a) no because no current
b) factory installed ammeter is faulty or DC output conductor is disconnected
Impressed current cathodic protection systems require a _____________ to convert AC to DC
rectifier
What code rule do you go to for cathodic protection
section 80
what does the national building code of canada provide
-minimum requirements during a buildings construction phase
Conductors for emergency lighting and fire alarm systems installed in a “high building” are required to have ________________
- a fire rating of one hour
what CEC code is used for emergency lighting
46
NBCC requires that all public exists must have light fixures that has a minimum of _____________ lux
50
2 main types of emergency lighting systems
-self contained- emergency lighting systems is installed on the same enclosures on batteries
-remote lamps and batteries- use remote lamps and batteries
batteries used for emergency lighting are rated by _______________
wattage caoacity- max amt of power the battery can supply for th emin NBCC 30 miniute requirement
formula to find lumens
lux x area
