313

Each motor used in a continuous-duty application and rated more than ___ hp shall be protected against overload.

1

Size the overloads for a motor with the following nameplate information:230 Volt - single phase 3 HP 14 Amps

16.1

Size the overloads for a motor with the following nameplate information:230 Volt - single phase 3 HP 14 Amps 40°C temperature rise

17.5

The service factor is nameplate information that is provided by the manufacturer and indicates that the motor can be overloaded to this percentage for a short period of time. For example, where a 7.5 hp motor normally draws 17 amps and has a service factor of 1.20, this means that it can pull approximately ___ amps for a short period of time without damage to the motor.

20.4

Determine the minimum size overload protection required for a 480-volt, 3-phase, 15 hp, continuous duty motor given the following information.* Design B * temperature rise - 50ºC* service factor - 1.12 * actual nameplate rating - 18 amps

20.7 amps

Size the overloads for a motor with the following nameplate information:230 Volt - 3-phase 71/2 HP 19 Amps

21.85

A NEMA Type ___ enclosure provides a degree of protection against windblown dust. Refer to NEC® Table 110.28.

3

Size the overloads for a motor with the following nameplate information:480 Volt - 3-phase 5 HP 4 Amps 50°C temperature rise Select one:

4.6

Size the overloads for a motor with the following nameplate information:480 Volt - 3-phase 5 HP 4 Amps 40°C temperature rise

5

A motor has the following nameplate information: 208 V 3-phase 15 HP 42 AmpsThe initial overloads were not sufficient to run the motor. What is the new rating of the overloads?

54.6

A motor has the following nameplate information: 208V 3-phase 15 HP 42 Amps 1.10 SFThe initial overloads were not sufficient to run the motor. What is the new rating of the overloads?

54.6

A motor has the following nameplate information:208V 3ph 15 HP 42 Amps 1.15 Service FactorThe initial overloads were not sufficient to run the motor. What is the new rating of the overloads?

58.8

A 480-volt motor circuit can be protected with a safety switch that is rated at ___ volts.

600

"Heaters" are installed in motor starters to protect ___.I. the motor against overloadII. the branch circuit conductors against overloadIII. the motor against short circuits and ground faults

I & II only

A 3Ø safety switch that is rated at 250 volts can be used as the disconnecting means for a ___ motor.I. 240-volt, 1Ø II. 277-volt, 1Ø III. 480-volt, 3Ø

I only

A 3Ø safety switch that is rated at 600 volts can be used as the disconnecting means for a ___-volt, 3Ø motor.I. 208 II. 240 III. 480

I or II or III

Circuit conductors (14 AWG) are installed between a 3-pole, 40-A circuit breaker in a panel and a motor. The circuit breaker protects the conductors against ___.I. overload II. short circuit III. ground fault

II & III only

A(n) ___ is an assembly of one or more enclosed sections having a common power bus and principally containing motor control units.

MCC

I or II or III

Refer to Figure 232.101. ___ could be used as a disconnecting means for a 2 horsepower, 240-volt, single-phase motor.

Neither I nor II

Refer to Figure 232.103. ___ could be used as a disconnecting means for a 5 horsepower, 240-volt, single-phase motor.

Either I or II

Refer to Figure 232.104. ___ could be used as a disconnecting means for a 2 horsepower, 240-volt, single-phase motor.

Y only

Refer to the Plan View of the electrical and equipment rooms below. A circuit breaker in Panel HA feeds the starter and the motor in the equipment room. There is a full-height wall between the two rooms. Which of the safety switches must be installed to satisfy the minimum requirements of the NEC®?

1

Refer to the motor nameplate shown in Figure 230.108. A NEMA starter will be used for this motor. The fewest number of heaters that can be installed in the starter per the NEC® is ___. The motor circuit is supplied from a 2-pole breaker in a 120/240-volt, 3Ø, 4-W panel.

1

Refer to the motor nameplate shown in Figure 230.115. A NEMA starter will be used for this motor. The fewest number of heaters that can be installed in the starter per the NEC® is ___. The motor circuit is supplied from a 1-pole breaker in a 120/240-volt, 3Ø, 4-W panel.

3

Refer to the nameplate and information shown in Figure 230.131. The fewest number of heaters required in a starter is ___.

The overcurrent protection for an MCC may be located ahead of or within the MCC.

True

II only

When a switch is used for the disconnecting means for a 1-phase motor operating at 240 volts, the switch can be of the ___ type.

Can a double-pole, single-throw (toggle) switch rated for 250 volts AC only and 20 amps be used as a disconnect for a 1.5 HP, 230-volt, single-phase motor that is stationary?Note: the NEC® considers a toggle switch to be a general-use snap switch. See the definition in Article 100.

Yes

All motor circuits require ___ protection. overload short-circuit ground-fault

all of these

When current transformer-type overload relays are used, overload current in the motor branch circuit conductors causes ___ in the current to the overload relay.

an increase

A 3-pole, 250-volt safety switch can be used as the disconnecting means for ___ motor circuit. a 2-wire, 120-volt, 1-phase a 2-wire, 208-volt, 1-phase a 3-wire, 208-volt, 3-phase a 3-wire, 240-volt, 3-phase

any of these

Inherent motor protection devices are built into the motor and are reset ___.

automatically

Motor controllers must be marked with ___.I. maximum rated voltage II. maximum hp or current rating

both I & II

A combination starter is a ___.I. disconnect switch II. motor starter

both I and II

A heater coil is a sensing device used to monitor the heat ___. -generated by excessive motor branch circuit current -created through ambient temperature rise

both a and b

A combination starter is a ___.

disconnect switch & motor starter

The motor overload unit for a single-phase motor fed from an ungrounded 2-wire, single-phase AC source will be placed in ___ conductor.

either

A 3Ø safety switch that is rated at ___ volts can be used as the disconnecting means for a 208-volt, 1Ø motor.I. 240 II. 600

either I or II

An individual disconnecting means shall be provided for each controller and shall disconnect the controller. The disconnecting means shall be located ___ the controller location.

in sight from

If an overload in a motor branch circuit persists for a long enough period of time, it can cause damage to the ___.

insulation on the motor windings & conductors supplying the motor

A motor will draw ___ than its rated nameplate current when heavily loaded.

more

Inherent motor protection devices are built into the ___ and are reset automatically.

motor

Inherent motor protection devices are built into the ___ and are reset ___.

motor, automatically

Circuit conductors (14 AWG) are installed between a 3-pole, 40-A circuit breaker in a panel and a motor starter. These conductors are also installed between the starter and the motor. When "heaters" (motor overload protectors) are installed in the motor starter, these protect the ___ against overload.

motors

When a horsepower-rated motor is to operate at a specified voltage, overload sizing is based on ___.

nameplate amps with consideration given to service factor

A branch circuit for a motor originates from a breaker in a panelboard. The circuit runs from the panel, to a motor starter, and finally to the motor. The panel and the starter are located in a room and are "within sight" of each other. The motor is located outside. A safety switch (or other type of disconnect) is ___.

required outside and (within sight of the motor)

When selecting overload protection for a motor, the motor's nameplate rating for ___ affect the selection.

service factor & temperature rise

Before resetting an overload relay on a starter, ___.

the cause of the overload must be found and corrected

To size motor overloads for a DC motor, the amperage found on ___ is used.

the motor nameplate