Basic Motor Controls-MC Article 430 - Motors, Motor Circuits, and Controllers

If the motor control circuit transformer is located in the controller enclosure, the transformer shall be connected to the _____ side of the control circuit disconnecting means.

Load

The motor controller shall have horsepower ratings at the application voltage not _____ the horsepower rating of the motor.

Lower than

Horsepower-rated attachment plugs, flanged surface inlets, receptacles, or cord connectors shall not be required for cord-and-plug-connected portable motors rated _____ hp or less.

1/3 hp

Conductors supplying several motors shall not be sized smaller than _____ percent of the full-load current rating of the highest rated motor, plus the sum of the full-load current ratings of all other motors in the group, plus the ampacity or other loads.

125

Each motor shall be provided with an individual controller.

true

Overcurrent protection for motor control circuits shall not exceed _____ percent if the conductor is based on Table 310.15(B)(17) and does not extend beyond the motor control equipment enclosure.

400

A motor disconnecting means can be a listed _____.

Any of these( molded case circuit breaker, motor-circuit switch rated in horsepower, molded case switch

The motor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the _____ current of the motor.

Starting

A branch-circuit overcurrent device can serve as the disconnecting means for a stationary motor of 1/8 hp or less.

True

An oil switch can be used as both the motor controller and disconnecting means on a circuit whose rating _____ or 100A.

does not exceed 1,000V

The motor disconnecting means for a motor shall _____ whether it is in the open (off) or closed (on) position.

plainly indicate

Motor control circuit conductors that extend beyond the motor control equipment enclosure shall have short-circuit and ground-fault protection sized not greater than _____ percent of value specified in Table 310.15(B)(16) for 60°C conductors.

300

For stationary motors of 2 hp or less and 300V or less on ac circuits, the controller can be an ac-rated only general-use snap switch where the motor full-load current rating is not more than _____ percent of the rating of the switch.

80

A switch or circuit breaker can be used as both the controller and disconnecting means if it _____.

All of these

A motor can be provided with combined overcurrent protection using a single protective device to provide branch-circuit _____ protection where the rating of the device provides the overload protection specified in 430.32.

All of these (short-circuit, ground-fault, motor overload

Unless overload protection is provided by other approved means, the minimum number of overload units required for a three-phase ac motor is _____.

Three

Motor controllers and terminals of control circuit devices shall be connected with copper conductors unless identified for use with a different conductor.

True

The disconnecting means for the controller and motor shall open all ungrounded supply conductors.

True

Overload devices are intended to protect motors, motor control apparatus, and motor branch-circuit conductors against _____.

excessive heating due to motor overloads and failure to start

A feeder supplying fixed motor load(s) shall have a protective device with a rating or setting _____ branch-circuit short-circuit and ground-fault protective device for any motor in the group, plus the sum of the full-load currents of the other motors of the group.

not greater than the largest rating or setting of the

Torque requirements for motor control circuit device terminals shall be a minimum of _____ lb-in. (unless otherwise identified) for screw-type pressure terminals used for 14 AWG and smaller copper conductors.

7

A motor controller shall open all conductors to the motor where not used as a disconnecting means.

False

The motor _____ currents listed in Tables 430.247 through 430.250 shall be used to determine the ampacity of motor circuit conductors and short-circuit and ground-fault protection devices.

full-load

Where more than one motor disconnecting means is provided in the same motor branch circuit, at least one of the disconnecting means shall be readily accessible.

True

Where the motor short-circuit and ground-fault protection devices determined by Table 430.52 do not correspond to the standard sizes or ratings, a higher rating that does not exceed the next higher standard ampere rating shall be permitted.

True

When an overload device sized in accordance with 430.32(A)(1) and (B)(1) is not sufficient to start the motor, higher size sensing elements shall be permitted if the trip current does not exceed _____ percent of the motor nameplate full-load current rating, when the motor is marked with a service factor of 1.12.

130

Feeder tap conductors supplying motor circuits, with an ampacity at least one-third that of the feeder, shall not exceed _____ ft in length.

25

The maximum rating or setting of an inverse time breaker used as the motor branch-circuit short-circuit and ground-fault protective device for a single-phase motor is _____ percent of the full-load current given in Table 430.248.

250

Branch-circuit conductors supplying a single continuous-duty motor shall have an ampacity not less than _____ rating.

125 percent of the motor's full-load current rating as determined by 430.6(A)(1)

Motor control circuit transformers, with a primary current rating of less than 2A, can have the primary protection device set at no more than _____ percent of the rated primary current rating.

500

The disconnecting means for a motor controller shall be designed so that it cannot _____ automatically.

Close

For general motor applications, the motor branch-circuit short-circuit and ground-fault protection device shall be sized based on the _____ values.

NEC Table

A separate overload device used to protect continuous-duty motors rated more than 1 hp shall be selected to trip at no more than _____ percent of the motor nameplate full-load current rating if marked with a service factor of 1.15 or greater.

125

The motor disconnecting means shall not be required to be in sight from the motor and the driven machinery location, provided _____.

All of these( the controller disconnecting means is lockable, in accordance with 110.25, locating the motor disconnecting means within sight of the motor is impractical, locating the motor disconnecting means within sight of the motor introduces additional or increased hazards to people or property

Motor control circuits shall be arranged so they will be disconnected from all sources of supply when the disconnecting means is in the open position.

True

A _____ shall be located in sight from the motor location and the driven machinery location.

disconnecting means

In determining the highest rated motor for purposes of 430.24, the highest rated motor shall be based on the rated full-load current as selected _____.

from Tables 430.247, 430.248, 430.249, and 430.250

If a motor disconnecting means is a motor-circuit switch, it shall be rated in _____.

horsepower

A _____ rated in amperes shall be permitted as a controller for all motors.

a and b (branch-circuit inverse time circuit breaker, molded case switch