202/302 Principles Flashcards
What is the force of gravity on earth?
9.81 Newtons
What is the symbol for temperature coefficient of resistance?
a (Alpha)
What is a conductor in terms of atoms?
Lots of free electrons in outer shell
What is an insulator in terms of atoms?
Few free electrons in outer shell
What is the multiplier and symbol for Pico?
p 10(-12)
What is the multiplier and symbol for Nano?
n 10(-9)
What is the multiplier and symbol for Micro?
u/p shape 10(-6)
What is the multiplier and symbol for Milli?
m 10(-3)
What is the multiplier and symbol for Kilo?
k 10(3)
What is the multiplier and symbol for Mega?
M 10(6)
What is the multiplier and symbol for Giga?
G 10(9)
What is the multiplier and symbol for Tera?
T 10(12)
What is resistance measured in?
Ohms
What are the dimension symbol and unit for luminous intensity?
Iv. Candela
What are the 8 multipliers?
Tera. Giga. Mega. Kilo. Milli. Micro. Nano. Pico
What is the symbol for luminous intensity?
cD
What is the formula for average power?
Average power = Work done ÷ Time (P=WD/T)
What is the formula for work done?
Work done = Force x Distance (W=FD)
What is the formula for kinetic energy?
Kinetic energy = 1/2 x Mass x Velocity(2)
(1/2MV(2)
What is the formula for potential energy?
Potential energy = Mass x Acceleration x height (PE=mah)
What is the formula for force?
Force = Mass x Acceleration (F=ma)
What is the formula for voltage?
Voltage = Current x Resistance (V=IR)
What is the formula for power?
Power = Current x Voltage (P=IV)
What is ohms law?
Resistance = voltage ÷ current
What is the formula for voltage drop?
(Mv/A/M) x Ib x L ÷ 1000
How do you find the total resistance in a circuit?
Add up the value of all resistors
Where in the On-Site Guide is Ca?
Table F1
Where in the On-Site Guide is In?
Table B6
Where in the On-Suite Guide is Cg?
Table F3
Where in the On-Suite Guide is Cf?
Appx F
Where in the On-Suite Guide is cable size and voltage drop?
Table F6
Where in the On-Suite Guide is Ci?
Table F2
What are the 3 types of conduit?
Metal. PVC. Flexible
What is the formula for Iz?
In ÷ (Ca x Cf x Cg x Ci)
What is the formula for Phi?
Phi = Beta x Area
What does magnetic current flowing away appear as?
A cross
What does magnetic current flowing towards appear as?
A point
What magnetic field is represented as a point?
Anticlockwise magnetic field
What magnetic field is represented as a cross?
Clockwise magnetic field
What is the formula for flux density?
Flux density = Current x Length
(Beta = IL)
What is the formula for magnetic force?
Magnetic force = Magnetic flux x Current x Length
What is magnetism?
The result of a movement of electrons
What is flux density measured in?
Tesla
What is the symbol for flux density?
B (Beta)
Which hand is used to determine the magnetic direction of a motor?
Left
Which hand is used to determine the magnetic direction of a generator?
Right
What is the difference between motors and generators?
Motors require electricity to spin. Generators spin to generate electricity
What does the thumb point to in a generator and motor?
Direction of motion
What does the 1st finger point to in a generator and motor?
Polarity of field
What does the 2nd finger point to in a generator and motor?
Polarity convectional current
What is the formula for parallel resistance?
R1(x-1) + R2 (x-1) + R3 (x-1) = RT RT (x-1)
What is the formula for series resistance?
R1 + R2 + R3 = RT
Why do we use a.c for distribution and transmission?
It reduces heat loss, energy loss and cost
At what voltage is electricity generated at?
20 - 27kV
What voltage is electricity transmitted at the grid system?
400kV or 275kV
What is the value of RMS?
0.707
What is the value of average?
0.363
How is a magnetic field created in a generator?
A D.C supply is added
What rotates the rotor in a generator?
The prime mover
How much energy never reaches the consumer due to heat?
8%
What are two negatives about pylons?
They are ugly, they use lots of land
What are 2 positives about pylons?
They are cheaper than installing cables, They do not require insulators
What is the maximum super grid voltage?
400kV
How many volts are considered extra low?
0 - 50 volts
What is the formula for working out transformer ratios?
VP÷VS NP÷NS IS÷IP
What does an AFDD protect against?
Fire
What does an AFDD stand for?
Arc fault detection device
What does SPD stand for?
Surge protection device
What does an SPD protect against?
Over Voltage
Why would someone choose to install a ring circuit?
To reduce voltage drop, to reduce losses on the final accessory
Which phase supplies are installed in newer homes?
3-phase
How much are the 3 phases out of each other?
120⁰
What’s positive about using 3-phase?
requires x2 the number of wires for x3 the power
How much is the voltage between each phase?
1.37 (Square root of 3?
What are the 4 types of isolation and switching?
Switching for mechanical maintenance,
Emergency switch off,
Functional switching,
Firefighters switch