Amazon Maintenance Technician Motor Controls & Variable Frequency Drives 2

Question 1

Which VFD parameter must be set to match the motor's rated speed specification?

Accepted Answer

Base (rated) frequency

Answer

Motor FLA setting

Answer

Motor horsepower rating

Answer

Input line voltage

Question 2

What VFD protection feature prevents damage caused by a high DC bus voltage condition?

Accepted Answer

Overvoltage (OV) protection

Answer

Overcurrent (OC) protection

Answer

Ground fault protection

Answer

Phase loss protection

Question 3

Why is an input line reactor commonly installed on a VFD?

Accepted Answer

To reduce harmonic distortion and protect the VFD from line transients

Answer

To step up voltage to the VFD input

Answer

To provide power factor correction at the motor

Answer

To filter high-frequency noise from the VFD output

Question 4

When performing lockout/tagout (LOTO) on a motor control center, what is the correct first step?

Accepted Answer

Identify all energy sources associated with the equipment

Answer

Apply lockout devices to all energy sources

Answer

Test to verify equipment is de-energized

Answer

Notify all affected employees

Question 5

How does a soft starter differ from a Variable Frequency Drive?

Accepted Answer

A soft starter only controls acceleration and deceleration, not running speed

Answer

A soft starter provides continuous speed control during normal operation

Answer

A soft starter uses DC power instead of AC

Answer

A soft starter does not require any programming

Question 6

What does the 'torque boost' parameter in a VFD accomplish?

Accepted Answer

Provides additional voltage at low frequencies to improve low-speed starting torque

Answer

Increases the maximum operating frequency of the motor

Answer

Reduces the motor acceleration ramp time

Answer

Extends the deceleration time to protect the mechanical system

Question 7

A motor rated 460V/3Ph/60Hz running from a VFD at 30 Hz will operate at approximately what percentage of its nameplate speed?

Accepted Answer

50%

Answer

25%

Answer

75%

Answer

100%