Previous Magnetism & Electromagnetic Induction Practice Test Next Open/Short/Ground Fault Theory Practice Test

BASIC NEC 2023

Motor Starting Methods & Motor Types Overview Practice Test

Free online motor starting methods and motor types practice test. 25 basic electrical questions on DOL starting, star-delta starters, VFDs, single-phase motor starting, and motor nameplate ratings. Good for electrician exam prep.

TOPICS COVERED

Basic Motor Categories Squirrel Cage Motor Wound Rotor Motor Synchronous Motor DOL Starting Definition DOL Starting Drawback

How this test works

Read each question carefully

Look for absolute words like always / never — they often distinguish the right answer.

Manage your time

You have 38 min for 25 questions. Skip tough ones and come back.

Progress is auto-saved

Your answers are saved locally — a page refresh won't lose your work.

Review your answers

After submitting you'll see every explanation and your NEC references.

The simplest way to start a motor is Direct-On-Line (DOL) — full voltage, all at once — but that draws a huge inrush current (6-8× full-load current). For larger motors or weak supplies, reduced-voltage starters (star-delta, autotransformer, soft starter) ease that stress, while a Variable Frequency Drive (VFD) goes further, controlling running speed too. Single-phase motors have their own problem: a single AC waveform doesn't create a rotating field, so they need help starting — through split-phase, capacitor-start, or shaded-pole designs.

25

Questions

38 min

Time

75%

Pass

Timer starts immediately. Progress is auto-saved.

Motor Starting Methods & Motor Types Overview Practice Test — Question List

Question 1: Electric motors can be broadly grouped into two main categories based on their power supply:

AC motors and DC motors
Fast motors and slow motors
Indoor motors and outdoor motors
Red motors and blue motors

Question 2: The most common type of AC industrial motor is the:

Squirrel cage induction motor
Wound rotor motor
Synchronous motor
Shaded-pole motor

Question 3: A wound rotor induction motor differs from a squirrel cage motor in that a wound rotor motor:

Has rotor windings connected to external resistance through slip rings, allowing adjustable starting torque and speed control
Has no rotor at all
Can only run on DC power
Never requires any maintenance

Question 4: A synchronous motor differs from an induction motor in that a synchronous motor:

Runs at exactly synchronous speed, locked to the supply frequency, rather than slightly slower
Cannot run on AC power at all
Always runs faster than the supply frequency allows
Has no relationship between its speed and the supply frequency

Question 5: Direct-On-Line (DOL) starting means a motor is started by:

Connecting it directly to full line voltage all at once
Gradually ramping voltage up over several minutes
Never applying any voltage to the motor
Only applying voltage to half of the motor windings

Question 6: The main drawback of Direct-On-Line (DOL) starting is that it:

Draws a very high inrush current, often 6 to 8 times the motor's full-load current
Draws less current than the motor's normal running current
Requires no wiring to the motor at all
Only works with DC motors, never AC motors

Question 7: Reduced-voltage starting methods are used mainly to:

Lower the starting current and mechanical stress on both the electrical system and the driven load
Permanently reduce the motor's horsepower rating
Increase the motor's inrush current even further
Convert the motor from AC to DC operation

Question 8: A star-delta (wye-delta) starter reduces starting current by first connecting the motor windings in:

Star (wye), then switching to delta once the motor is up to speed
Delta, then switching to star once the motor is up to speed
Neither star nor delta — it uses a completely different winding pattern
Star only, with no switching ever taking place

Question 9: An autotransformer starter reduces starting current by:

Using a tapped transformer to apply a reduced voltage to the motor during starting
Disconnecting the motor from the supply entirely
Doubling the applied voltage during starting
Converting the motor to DC operation temporarily

Question 10: A solid-state soft starter reduces motor starting stress by:

Using electronic components (like SCRs) to gradually ramp up the applied voltage
Applying full voltage instantly, just like DOL starting
Physically disconnecting the motor windings permanently
Only working with single-phase motors

Question 11: A Variable Frequency Drive (VFD) controls motor speed by:

Varying the frequency (and voltage) supplied to the motor
Physically adding gears between the motor and the load
Only switching the motor fully on or fully off
Changing the motor's wire gauge automatically

Question 12: Compared to a soft starter, a Variable Frequency Drive (VFD) offers the added ability to:

Continuously control the motor's running speed, not just smooth its starting
Run the motor on DC power exclusively
Eliminate the need for any motor protection
Work only with single-phase motors

Question 13: A basic single-phase induction motor has trouble starting on its own because:

A single AC waveform does not naturally create a rotating magnetic field
Single-phase motors cannot run on AC power at all
Single-phase motors have no rotor
Single-phase power does not actually exist

Question 14: A split-phase motor creates starting torque using a separate start winding that has:

Higher resistance than the main winding, creating a phase shift between the two windings' currents
Exactly the same resistance as the main winding
No electrical connection to the motor at all
A permanent magnet instead of copper windings

Question 15: A capacitor-start motor improves on a basic split-phase motor by:

Adding a capacitor in series with the start winding to create a stronger phase shift and more starting torque
Removing the start winding entirely
Adding a second rotor
Running exclusively on DC power

Question 16: A capacitor-start-capacitor-run motor differs from a simple capacitor-start motor in that it:

Keeps a capacitor in the circuit (often a different, smaller one) even after starting, improving running performance
Removes all capacitors immediately after starting
Uses no start winding whatsoever
Only functions on three-phase power

Question 17: A shaded-pole motor is a simple, low-cost, low-torque single-phase motor commonly used in:

Small fans and light-duty appliances
Large industrial conveyor systems
Heavy-duty crane hoists
High-voltage transmission equipment

Question 18: In a split-phase or capacitor-start motor, the centrifugal switch is used to:

Disconnect the start winding once the motor reaches roughly 75% of its running speed
Permanently disconnect the motor from all power
Connect the start winding only after the motor stops
Increase the supply voltage to the motor

Question 19: "Full Load Amps" (FLA) on a motor nameplate indicates:

The current the motor draws when operating at its rated full load
The current the motor draws only while completely off
The motor's physical weight in amperes
The motor's voltage rating

Question 20: A motor's "Service Factor" (SF), shown on its nameplate, indicates:

How much above its rated horsepower the motor can safely handle for short periods without overheating
The motor's exact operating voltage
The number of years the motor is warrantied for
The motor's physical mounting dimensions

Question 21: "Locked Rotor Amps" (LRA), often represented by a code letter on a motor nameplate, indicates:

The very high current the motor draws for an instant when first started, with the rotor not yet turning
The current the motor draws while completely disconnected from power
The motor's continuous running current at half load
The current rating of the motor's mounting bolts

Question 22: NEMA Design B is considered the "standard" motor design among the NEMA design letters (A, B, C, D) mainly because it offers:

A good balance of normal starting torque and normal starting current suitable for most general-purpose applications
The highest possible starting torque of all four designs, with no drawbacks
The ability to run exclusively on DC power
Zero starting current under any condition

Question 23: A motor labeled with a "NEMA Premium" efficiency rating indicates:

The motor meets a defined higher standard for energy efficiency compared to standard-efficiency motors
The motor is guaranteed to never fail
The motor can only run at half its rated speed
The motor requires no electrical connection at all

Question 24: A motor rated for "continuous duty" is designed to:

Run indefinitely at its rated load without exceeding safe temperature limits
Only run for a maximum of 30 seconds at a time
Never be started more than once in its lifetime
Only operate on backup generator power

Question 25: A large motor is being installed on a site with a weak utility supply that cannot tolerate a high inrush current. The best choice of starting method would most likely be:

A reduced-voltage method, such as a star-delta starter, autotransformer starter, or soft starter
Direct-On-Line (DOL) starting, since it is always the best choice
No starting method at all — simply never start the motor
Doubling the motor's nameplate voltage rating

EXAM CARD BASIC

Questions25

Time limit38 min

Pass score75%

Code editionNEC 2023

DifficultyIntermediate

Last reviewedJun 2026

Timer starts immediately. Progress is auto-saved.

Source: NEC 2026 (NFPA 70)