final Flashcards
(29 cards)
Most power distribution system supply what type of current, and how much of the world is currently using this type of system.
AC
over 90%
voltage drop calculations
2KIL/A
1.73KIL/A
k=12.9 for copper
effective, peak, average, and RMS voltages
RMS = nominal (120 240 480 etc) peak = RMS X 1.414 average = .636 X PEAK RMS = Effective
When studying inductors and capacitor we know current flow is opposed by its _____ value that is expressed in ohms
Reactance
What is Lens law and how does it interact with EMF and CEMF on inductors?
EMF = electromotive force
CEMF = counter electromotive force
magnetic field opposes changes in voltage
EMF and CMF are 90 degrees out of phase
Know how to change inductance and capacitance into reactive values.
Inductive reactance= XL = 2 x 𝛱 x f x L (L in Henrys, f is frequency Hz, 6.28 for 2 x 𝛱)
Capacitive Reactance = XC = 1 / (2 x 𝛱 x f x C)
(C in Farads, f is frequency Hz, 6.28 for 2 x 𝛱)
Calculate 3 inductors in series/parallel, and 3 capacitors in series/parallel
inductors: work exactly like resistors
capacitors: work opposite of resistors
What is an atom and what are the different parts of it?
Atom = smallest piece and element can be broken into without changing its properites.
Electrons
neutrons
protons
DC batteries when placed in series, what is additive, in parallel, what is additive?
In series voltages add. In parallel voltage is constant so the capacity (amperage or amp/hours add
What’s the difference between a primary battery cell and a secondary cell?
Secondary can be recharged primary cannot
What is the difference between the electron flow theory and the conventional flow theory?
electron flow theory flows negative to positive
Define Volt, Ampere, Watt, and Ohm
Volt = electromotive force the push
Ampere = 1 coulomb (6.28X1018) electrons per second
Ohm = the resistance or opposition to flow also use for reactance
Watt = power the work that can be done.
Earth is a poor conductor, which makes it have a high_______. We need to consider this when we are doing our grounding and bonding.
resistance
When designers of equipment systems dedicated specific cable type connector type and topology to be used for wiring systems
Structured, application dependent
which of the following standards is the basis for the administration of telecommunication infrastructure in commercial buildings
TIA / EIA 606A
it is recommend that utp and stp backbone cables are limited to no more than
295 ft
which of the following is not one of the varieties of inside cable recognized by the NEC?
Commercial Cable
Which of the following may not be used within the stud walls of an office building?
CMX
For a given cable as frequency decreases the NEXT in Db
increase
For a given cable as frequency decreases attenuation
decrease
ANSI TIAA 569 standard says no conduit shall be longer than
30 meters
Minimum of ____ inches of headroom above a cable tray?
12 inches
Administrative label color for horizontal cables
BLUE
Class IV administration addresses infrastructure with multiple sizes.
true
