Deck 23: Selsyn Units

Question 1

In a three-phase motor installation, what are three specific facts that must be determined for each of the three branch circuits constituting the load of the installation?

Answer 1

The three specific facts that must be determined for each of the three branch circuits constituting the load of the installation are:
• The size of the conductors for each three-phase, three-wire branch circuit
• The fuse size to be used for short-circuit protection
• The size of the thermal overload units to be used for running protection

Question 2

Wire types and sizes are selected by the ambient temperatures of the place of installation and the economics of the total installation, such as the minimum size of conduits, cost of the wire sizes, and labor cost for installing the various selections.

Answer 2

True

Question 3

The NEC® guides an electrician through the main components of the calculation, thus providing all the information that is necessary for a motor installation.

Answer 3

False

Question 4

List two of the many facets to the correct installation of a motor.

Question 5

The branch-circuit, short-circuit protection of a wound-rotor induction motor is required by Table 430.52 of the Code not to exceed 150% of the ____________________ running current of the motor.

Question 6

When the conductors of a feeder supply two or more motors, the required wire size is determined using Code rules.

Question 7

NEC® Article 430.52 Exception 1 states that if the values for branch-circuit protective devices as determined using the percentages in Table 430.52 do not correspond to the standard device sizes or ratings, then the nearest smaller size rating or setting should be used.

Question 8

The work of the modern electrician requires a knowledge of National Electrical Code® requirements that govern three-phase motor installations and the ability to apply these requirements to installations.

Question 9

The term ____________________ is synonymous with ampere capacity.

Question 10

NEC 430.32(E) states that the secondary circuits of wound-rotor induction motors, including the conductors, controllers, and resistors, shall be considered as protected against overload by the motor running overcurrent protection in the ____________________ circuits.