26211 Motor Control

A motor overload relay consists of a current-sensing unit and a mechanism activated by the sensing unit that ____.

• dissipates excess current

• opens the motor circuit

• trips an alarm

• decreases motor speed

If low-voltage and high-voltage cables must be placed in parallel runs, they should be separated by at least 6" (150 mm) in order to protect the low-voltage conductors from ____.

• noise

• corrosion

• heat

• vibration

On magnetic contactors, which contacts are said to be normally open (NO)?

• All contacts that are functioning correctly

• Those that are together when the relay is de-energized

• Those that are apart when the relay is de-energized

• All contacts that are not functioning correctly

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-5

Lighting contactors are rated for ____.

• high horsepower loads

• low inrush currents and high voltages

• low inrush currents and low voltages

• high inrush currents

Low-voltage remote control switching relays use ____.

• a split coil
• no coil

• a single coi

• four coils

Tags

NGSS.HS-PS2-5

NGSS.HS-PS3-3

Which of the following can provide motor overload protection but have the disadvantage of being nonrenewable?

• Dual-element or time-delay fuses

• Circuit breakers

• Solenoids

• Overload relays

An electromagnetic device that can be used to multiply the switching function of a pilot device is a ____.

• switch

• timer

• thermistor

• control relay

The two classifications of overload relays are thermal and ____.

• magnetic

• shading

• eutectic

• bimetallic

When making connections to reverse the rotation of a motor, ____. connect lines L1, L2, and L3 to the motor terminals T1, T2, and T3, respectively

• L1 is connected to motor terminal T3, and L3 is connected to motor terminal T1

• L1 is connected to motor terminal T2, and L3 is connected to motor terminal T1

• L1 is connected to motor terminal T2, and L3 is connected to motor terminal T3

• L1 is connected to motor terminal T3, and L2 is connected to motor terminal T1

Tags

NGSS.HS-PS2-5

Mechanically held relays and contactors are often used because ____.

• they have fewer coils than electrically held devices

• they have more coils than electrically held devices

• they are quieter than electrically held devices

• they are more reliable than electrically held devices