Motors branch circuit devices and protection NEC 430
_____and_____ are the most common method's for establishing suitability for motor branch circuits.
Labeling , Listing
where in article 430 can you find the requirements for determining conductor ampacity and motor ratings?
430.6
when does the primary inrush of current occur in a transformer?
when it is energized
All OCPDS shall have a rating equal to or greater than the __________.
Available Fault Current
OCPDs must selectively coordinate for the _____ over currents possible for the application.
full range of
Overcurrent protection for motor circuits can be broken into two parts: motor and branch-circuit overload protection and motor branch circuit short circuit and ground protection. In which two NEC sections are these requirements found?
NEC article 430.32, 430.52
Section ___ ___ required fuses used for motor overload protection to be inserted in each ungrounded and grounded conductor if the supply system is a 3-wire, 3-phase AC with one conductor grounded. (corner grounded DELTA)
430.36
What two formulas are used to calculate the Primary and Secondary currents in a transformer over 1000v in a Unsupervised location?
Primary I= kVA x 1000/V x 1.73
Secondary I x 1.25
________ do not have series ratings.
Fuses
When a overcurrent occurs on a selectively coordinated system on the ______ OCPD opens to interrupt the overcurrent.
Nearest Line-side
According to the NEC, select the allowed uses for a magnetic motor starter
motor controller, Motor overload protection
where can you find the requirements for the disconnecting means of an adjustable-speed drive system?
430:128
Note 1 to table 450.3(A) permits an OCPD of the next higher ________ if the calculation does not correspond to an available OCPD size.
Commercially available size
What is the biggest disadvantage of a series rated system, when under certain Short circuit conditions ?
The Line-side OCPD must open to protect the load-side circuit breaker
Ground-fault protection of equipment is a protective system intended to provide protection for damaging ____ fault currents.
Line-to-Ground
A single-phasing condition subjects a 3-phase electric motors to the worst possible case of ______ ____.
Voltage Imbalance
The ampere rating of the disconnecting means is required to be at least _______of the sum of all currents at he rated-load condition determined in accordance with 440.12(b)(1)
115%
For transformers with a high-inrush applications where the overcurrent device is sized close to the full-load current, An _______ fuse may be preferred to prevent nuisance openings. ( 1000 volts, nominal, or less)
Time-delay
Adequate OCPD interrupting rating , by itself _____ensure that load-side electrical equipment will be provided with adequate short-circuit protection
Does not
Where is GFPE not allowed to be installed on transfer switches of essential electrical systems?
Load-Side
what equipment can be used to provide motor controller/overload protection,,
Adjustable speed drive, contactor with overload relay Electronic overload protection, soft-start motor controller
A controller serving more than one motor-compressor or a motor-compressor and other loads is required to have a continuous-duty full-load current rating and a locked-rotor current rating not less than the combined load as determined in accordance with ______?
440.12(b)
what formula would you use to calculate primary current of a transformer 1000 volts or less.
(kVA x 1000)/ 1000
Most often, the SCCR for fusible panelboard and switchboards is determined by the interrupting rating of the fuses in the equipment up to a maximum of _____.
200kA
According to the NEC, GFPE is required if the feeder disconnect is rated 1000 Amperes or more and is installed on a solidly grounded wye system of more than _______
150V to ground.