journeyman test notes
the rotating conductor LOOP is colled a ...
"ROTOR" or "Armature "
wireway splices and taps [376.56]
....shall not fill more than 75% of the wiring space at any cross section.
sizing wireway
...are common used where access to the conductors within the raceway is required to make terminations, splices, or taps to several devices in a single location.
"SLIP or COLLECTOR rings and carbon brushes
...are used to connect the output voltage from the generator to an external circuit.
in alternative current always opposes the change in current flow
1- CEMF,or BACK-EMF : counter electromotive force 2- EDDY Currents: 3- conductor shape
IMPORTANT: stranded conductors [310.106(C)]
8AWG and largest shall be straded when installed in a raceway.
Universal motor
A MOTOR THAT RUNS ON DIRECT OR ALTERNATING CURRENT. used for vacuum cleaner, electric drill,mixer, and light household appliance. the problem with commtator is that as the motor operates, motor part rub against each other and wear out.
definition metal wireway [376.2]
A sheet metal raceway with hinged or removable covers for housing and protecting electric conductors and cable , and in which conductors are placed after the raceway has been installed.
Series wound DC motor
A type of dc motor in which the armature (rotor) and field circuits are connected in a series arrangement, have poor speed regulation, and slow down considerably when a load is applied.
Shunt-wound dc motor
A type of dc motor in which the field coils are connected in parallel with the armature(ROTOR) and have relatively high resistance, is its ability to maintain constant speed under load.
flexible cord article
ARTICLE 400 table 400.5 and 405 (B)
in fixture wire article
ARTICLE 402 table 402.3 to 402.5
310.15,(B)(3)(a)
Adjustment for MORE THAN 3 current carrying conductors in conduit/RACEWAY.
NEC specifies the continuity of the neutral conductor of a multiwire branch circuit
CAN'T be dependent upon any wiring device [300.13(B)]
where conductors of different size are mixed together in a raceway
CHAPTER 9 CONTAINS information necessary to calculate the required raceway size
ANNEX C
Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the SAME SIZE
Equipment 100A and less[110.14(C)(1)(a)(3)]
Equipment terminals rate 100A or less and PRESSURE CONNECTOR TERMINAL#14 AWG through 1AWG , shall have the conductor sized to the 60C° temp rating in table 310.15(B)(16)
Exception 100A or less
If the terminating on equipment rated 75C° can be size column 75C° table 310.15(B)(16)
letter on conductor insulation [table 310.104 (A)]
No H = 60C° insulation rating H. = 75C° insulation rating HH. = 90C° insulation rating N. = nylon outer cover R. = thermoset insulation T. =thermoplastic insulation U. = underground W. = Wet or damp location X. = Cross linked polyethylene insulation -2- = 90C° insulation rating (RHW-2/USE-2)
SYNCHRONOUS MOTOR (AC MOTOR)
Operates at a constant speed up to full load The rotor speed is equal to the speed of the rotating magnetic field of the stator; there is no slip. Often used where the exact speed of a motor must be maintained Example: Timing such as time keeping, (clocks)
Fast-Acting Fuses
Regular and fast-acting fuses blow instantaneously--they protect lighting, electronic and other household circuits. Equipment on these circuits is sensitive to current surges.
Slow-Blow Fuses
Slow blow (time delay) fuses have built-in time delay features that prevent them from blowing during intermittent current surges (large motors, air conditioners and dryers). Time delay fuses blow under constant or repeated current overload conditions.
where multiple conductors of the SAME size are installed together in a raceway, the max number of conductors permitted can be determinate
TABLES in ANNEX C
310.15(B)(3)(c)
Temperature adjustment in conduit in sun on roof
determinating size overcurrent 800A or less 240.4 (B)
after correction ambient temperatures 310.15(B)(2)(a) after conductor bundling adjustment 310.15(B)(3)(a) or BOTH NEXT RATING BREAKER SISE<370A=400A breaker>
determinating size overcurrent 800A or over 240.4 (B)
after correction ambient temperatures 310.15(B)(2)(a) after conductor bundling adjustment 310.15(B)(3)(a) or BOTH . shall have a rating of not less than the rating of the overcurrent device . ,<1260A= 1200A size breaker>
EDDY Currents:
all independent currents that are produced as result of the expanding and collapsing magnetic field drim an alternative current.
INDUCTIVE REACTANCE (CEMF)
alternative current flow in a conductor is limited by the conductor's resistance and self-induced Volatage(CEMF), these acts to oppose the change in current glowing in the conductor. and these property is colled "INDUCTIVE REACTANCE ".
inductors and Capacitors
are energy stores Devices in ALTERNATING CURRENT and DIRECT CURRENT CIRCUIT.
conductors smaller than #14 are permitted
class 1 remote control circuits[725.43] fixtures wire[402.6] motor control circuits [table 430.72(B)]
when the conductor are installed in a raceway
conductor fill is limited to the above percentages.
note( 1) to chapter 9 tables
conductors at the same size and insulation, raceway can be using Annex C
CHAPTER 9
contains information necessary to calculate size raceway with DIFFERENT SIZES CONDUCTORS
chater 9, table 4
dimension and percent area for fill all raceway .
note (8) Chapter9 tables
dimensions for bare conductors are listed in chater 9,table 8
210.4(B)
each multiwire branch circuit MUST HAVE A means to simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates.
wireway conductors limited fill [376.23(A)]
fill limited to 20% conductor fill
wound rotor motor
http://ecmweb.com/content/wound-rotor-motors-high-torque-and-adjustable-speed. ...Are used only in special applications because of their complexity. these kind of motor only operate on 3 phase alternative current power.the rotor winding are connected in a WYE configuration and the point of the WYE ARE BROUGHT out through slip to an external controller.
note (4) to chapter 9 tables raceway not exceeding 24" in length
if NOT exceed 24" in length it's permitted to be fill to 60 %.
APPARENT POWER (VA)
if you measure voltage and current in an INDUCTIVE AND CAPACITIVE circuit, and multiply them together, the product is the...
EFFICIENCY( EFF )
in the transfer of energy. there are power losses (waste) in the conductor, the power supply, and the load itself . it is ALWAYS 1 OR LESS. EFF= output watt/ input watt.
TRUE POWER (W)
is the ENERGY CONSUMED, and is expressed...
compact stranding
is the result of a manufacturing process where a standard conductor is compressed to the extent that voids between strands este eliminated.
CHAPTER 9 TABLE 1 NOTE (2)
jamming [interferencia] : when 3 conductors are pulled into the raceway, they will occasionally flatten out.
CHAPTER 9 TABLE 1
list the max percent of the cross sectional area of permitted dor the installation of conductors and cables.
[314.16] and table 314.16(A)
metal box volume Box fill
marking on hermetic refrigerant motor compressors and Equipment [440.4(B)]
muiltimotor equipment shall be have visible nameplate with the MIN conductor ampacity and the MAX rating of the branch circuit /short circuit /and ground fault protective device. min=30 A [conductor sizing=10AWG] max = 50 A [overcurrent device= 50A]
Note (5) Chapter 9 tables
multiconductor cables and fiber cables AREN'T included in chapter9, use the actual dimensions from the manufacturer for raceway sizing .
note (9) chapter 9 tables
multiwire conductor and optical fiber are treated as a single conductor for raceway sizing.
raceway [300.17]
must be large enough to avoid damaging the insulation when the conductors are pulled into the raceway
IMPORTANT
nec chapter9 table 5 to 8
Article 240
overvurrent device
CHAPTER 9 TABLE 1 NOTE(1)
percent fill is based on common conditions where the length of the conductor and the number of raceway bends within reasonable limits.
min size conductors
residencial and commercial, and industrial locations #14AWG
240.6 (A)
size overcurrent device (BREAKERS)
Conductors OVER 100A and largest 1AWG[110.14(C)(1)(b)(1)]
sized 75C° column table310.15(B)(16)
termimal rate 90C° [110.15(C)(2)]
the 90C° ampacity column of the table 310.15(B)(16) can be used for separately installed connector if ten conductor and terminals are rated at least 90C° .
table 310.104(A)
the difference in the insulation thickness between RHH ANN THE REST kind of conductor
376.21
the max size conductor permitted in a raceway in a wireway SHALL NOT BE larger than that for which the wireway is designer.
Squirrel Cage Induction Motor (AC MOTOR )
the most common type of alternating current motor, which HAS NO PHYSICAL Connection between its rotating members (THE ROTOR) ,and the stationary member surrounding it (stator)
Note(2) to Chapter 9 tables
the percentage listed in table 1 apply only to complete raceway systems and aren't intended to apply to sections of raceways used to protect wiring from physical damage.
NEC Requirements 430.32(A)(1)
to protect the motors against excessive heat from an overload , standard overload protection devices to be sized at 115 to 225 % of the motor FLA rating 1. motors with a marked service factor of 1.15 and UP= 125% NP. 2.motor with marked temperature rise 40C° and DOWN=125%NP. 3 All other motors =115% NP.
CONDUCTORS expressed AWG OR KCMIL [110.6]
typically form 18 up to 4/0 AWG, LARGEST THAN 4/0 are expressed Kcmil.
Note (6) chapter 9 _ different size conductors
use Table 4, 5, 5A when sizing raceway for conductors of different sizes.
Table 314.16(A)
volume Allowance required per conductors.
UNIT POWER FACTOR
when an alternative current circuit supplies power to A PURE RESITIVE LOAD , such as incandescent lightning. heater element(range, heater lamp etc), the circuit voltage and current are in phase with each other.
Note (3) to chapter 9 tables
when equipment grounding or bonding conductors are installed, the actual area of the conductor Shall be used when calculating raceway fill
conductor shape
when the conductor is coiled into the adjacent loops(winding) the expanding and collapsing FLUX lines of alternating current flowing through the conductor loops interact and add together to create a strong overall magnetic field.
Note(4) Chapter 9 tables
when the raceway DOESN'T exceed 24" in length, it's permitted to be filled to 60% of its total cross sectional area in concordance with TABLE 4 CHAPTER 9.
motor locked Rotor Current (LRC)
which Is about six times the running current value,and causes the motor winding to overheat to the point that will be destroyed if the current isn't quickly stopped.
strand conductor
wire with several bare wire composition in the same conductor, it can vary among 7 to 36 bare stranded.
reversing the rotation of a direct Current motor
you must reverse either the stator or the armature magnetic field.