Science Engineering Electrical Engineering
Comprehensive Guide to Naval Ship Electric Motors and
Controllers
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Terms in this set (456)
What does Chapter 302 cover? Description and non-specific operating instructions for motors and controllers
other than those used for electric propulsion.
Where can you find instructions for electric propulsion NSTM Chapter 235, Electric Propulsion Installations.
installations?
What chapter provides maintenance and care instructions NSTM Chapter 300, Electric Plant-General.
for motors and controllers?
What should you refer to for specific information about a Applicable Allowance Parts List (APL) and manufacturer-provided information
particular motor or controller? such as identification plate data, connection diagrams, and technical manuals.
What safety precautions should be observed when Always observe safety precautions to avoid injury and equipment damage; refer
working with electrical equipment? to NSTM Chapter 300 for electrical safety precautions.
What is a critical safety consideration when using Ensure the grounding conductor is connected correctly to prevent electric shock.
portable tools or equipment?
What types of electric motors are provided on combatant Navy Service A motors for essential auxiliaries (heavy-duty, high-impact-shock-
ships? resistant) and Navy Service C motors for non-essential auxiliaries (commercial
marine type).
What is the duty cycle rating for motors installed in ships? Motors are rated for continuous, intermittent varying, or short time duty as required
by the driven auxiliaries.
,What voltage variation can motors installed in ships Motors are designed to operate at ± 10% variation in voltage indicated on the
tolerate? nameplate.
What frequency variation can AC motors tolerate? AC motors are designed to operate at ± 5% variation in frequency indicated on the
nameplate.
What type of motors are primarily used on naval ships? Polyphase induction motors.
How do polyphase induction motors generate A rotating magnetic field induced by currents in the primary winding induces
mechanical force? voltages and currents in the secondary winding, turning the rotor.
What is synchronous speed in relation to induction The speed of rotation of the rotating magnetic field, calculated as 120 times the
motors? frequency of the power supply (Hz) divided by the number of poles in the primary
winding.
What is slip in the context of induction motors? The difference between synchronous speed and rotor speed.
What are the synchronous speeds for 60 Hz motors with 2 poles: 3600 rpm; 4 poles: 1800 rpm; 6 poles: 1200 rpm; 8 poles: 900 rpm.
different pole counts?
What is the normal full load speed for a 2-pole motor? 3450 rpm.
What is the normal full load speed for a 4-pole motor? 1740 rpm.
What is the normal full load speed for a 6-pole motor? 1160 rpm.
What is the normal full load speed for an 8-pole motor? 870 rpm.
What type of motors are typically used on non- Commercial marine type motors.
combatant ships?
What happens if a motor operates outside its specified There may be a loss in performance or a decrease in the motor's lifespan.
voltage or frequency limits?
What is the primary winding in a polyphase induction The power supply.
motor usually connected to?
What does the secondary winding in a polyphase An electrical connection to the power supply.
induction motor lack?
What is the significance of the nameplate on a motor? It provides important information such as voltage, frequency, and duty cycle
ratings.
What are the synchronous speeds for 2-pole motors? 3600 rpm
What is the construction feature of squirrel cage induction They have a rotor winding made of longitudinal bars in slots, short-circuited by
motors? rings at the ends.
, How does the rotor winding in a squirrel cage induction It is energized by induction produced from the slip frequency.
motor operate?
What additional considerations are needed for squirrel They require a speed control system with a constant frequency to voltage ratio.
cage induction motors used in variable speed systems?
What happens to a 440-volt 60-Hz motor at 50% It operates at 50% speed (220v, 30 Hz).
frequency and voltage?
What type of motor is required for a speed control system A special design, variable voltage, high slip, high heat dissipation squirrel cage
using variable voltage at constant frequency? induction motor.
What are the characteristics of the wound-rotor induction It has individually insulated coils and uses external resistors for speed and current
motor? adjustments.
How can the line current (IL) for three-phase motors be IL = [746 (hp)]/[1.73(EL)(pf)(eff)]
calculated?
What is the formula to calculate kVA input for three- kVA input = [1.73 (IL) (EL)]/1000
phase motors?
What is the formula for torque in relation to horsepower Torque (ft/lb) = [5250 (hp)]/rpm
and rpm?
What types of DC motors are mentioned in the notes? Shunt, series, compound, or stabilized shunt motors.
What is the significance of the slip frequency in squirrel It is the frequency that induces current in the rotor winding.
cage induction motors?
What is the relationship between torque and horsepower hp = [2π(rpm)(torque)]/33000.
for motors?
What are the two methods of connecting one primary Two ways of connecting for two synchronous speeds in the ratio of 2 to 1.
winding in multiple-speed squirrel cage induction
motors?
What is the total number of synchronous speeds for two Four synchronous speeds.
primary windings with two speeds in the ratio of 2 to 1?
What happens to the motor current in a variable voltage The motor draws high current throughout the speed range.
control system?
What is the peak current and heat dissipation requirement It occurs at approximately two-thirds rated speed and load.
for a variable voltage control system?
What is the approximate full load speed for normal-slip The speeds are approximate and may vary for motors of special design.
motors according to the table?
What is the purpose of external resistors in wound-rotor To adjust motor speed, starting current, and other characteristics.
induction motors?
Comprehensive Guide to Naval Ship Electric Motors and
Controllers
Leave the first rating
Save
Students also studied
ASVAB- Electrical Series circuits Jeppesen Powerplant Ch. 8 Section ... Unit 2 p
58 terms 11 terms 15 terms 27 terms
fitzyboy04 Preview Rylinhandley Preview Demetrius_Carty2 Preview rea
Terms in this set (456)
What does Chapter 302 cover? Description and non-specific operating instructions for motors and controllers
other than those used for electric propulsion.
Where can you find instructions for electric propulsion NSTM Chapter 235, Electric Propulsion Installations.
installations?
What chapter provides maintenance and care instructions NSTM Chapter 300, Electric Plant-General.
for motors and controllers?
What should you refer to for specific information about a Applicable Allowance Parts List (APL) and manufacturer-provided information
particular motor or controller? such as identification plate data, connection diagrams, and technical manuals.
What safety precautions should be observed when Always observe safety precautions to avoid injury and equipment damage; refer
working with electrical equipment? to NSTM Chapter 300 for electrical safety precautions.
What is a critical safety consideration when using Ensure the grounding conductor is connected correctly to prevent electric shock.
portable tools or equipment?
What types of electric motors are provided on combatant Navy Service A motors for essential auxiliaries (heavy-duty, high-impact-shock-
ships? resistant) and Navy Service C motors for non-essential auxiliaries (commercial
marine type).
What is the duty cycle rating for motors installed in ships? Motors are rated for continuous, intermittent varying, or short time duty as required
by the driven auxiliaries.
,What voltage variation can motors installed in ships Motors are designed to operate at ± 10% variation in voltage indicated on the
tolerate? nameplate.
What frequency variation can AC motors tolerate? AC motors are designed to operate at ± 5% variation in frequency indicated on the
nameplate.
What type of motors are primarily used on naval ships? Polyphase induction motors.
How do polyphase induction motors generate A rotating magnetic field induced by currents in the primary winding induces
mechanical force? voltages and currents in the secondary winding, turning the rotor.
What is synchronous speed in relation to induction The speed of rotation of the rotating magnetic field, calculated as 120 times the
motors? frequency of the power supply (Hz) divided by the number of poles in the primary
winding.
What is slip in the context of induction motors? The difference between synchronous speed and rotor speed.
What are the synchronous speeds for 60 Hz motors with 2 poles: 3600 rpm; 4 poles: 1800 rpm; 6 poles: 1200 rpm; 8 poles: 900 rpm.
different pole counts?
What is the normal full load speed for a 2-pole motor? 3450 rpm.
What is the normal full load speed for a 4-pole motor? 1740 rpm.
What is the normal full load speed for a 6-pole motor? 1160 rpm.
What is the normal full load speed for an 8-pole motor? 870 rpm.
What type of motors are typically used on non- Commercial marine type motors.
combatant ships?
What happens if a motor operates outside its specified There may be a loss in performance or a decrease in the motor's lifespan.
voltage or frequency limits?
What is the primary winding in a polyphase induction The power supply.
motor usually connected to?
What does the secondary winding in a polyphase An electrical connection to the power supply.
induction motor lack?
What is the significance of the nameplate on a motor? It provides important information such as voltage, frequency, and duty cycle
ratings.
What are the synchronous speeds for 2-pole motors? 3600 rpm
What is the construction feature of squirrel cage induction They have a rotor winding made of longitudinal bars in slots, short-circuited by
motors? rings at the ends.
, How does the rotor winding in a squirrel cage induction It is energized by induction produced from the slip frequency.
motor operate?
What additional considerations are needed for squirrel They require a speed control system with a constant frequency to voltage ratio.
cage induction motors used in variable speed systems?
What happens to a 440-volt 60-Hz motor at 50% It operates at 50% speed (220v, 30 Hz).
frequency and voltage?
What type of motor is required for a speed control system A special design, variable voltage, high slip, high heat dissipation squirrel cage
using variable voltage at constant frequency? induction motor.
What are the characteristics of the wound-rotor induction It has individually insulated coils and uses external resistors for speed and current
motor? adjustments.
How can the line current (IL) for three-phase motors be IL = [746 (hp)]/[1.73(EL)(pf)(eff)]
calculated?
What is the formula to calculate kVA input for three- kVA input = [1.73 (IL) (EL)]/1000
phase motors?
What is the formula for torque in relation to horsepower Torque (ft/lb) = [5250 (hp)]/rpm
and rpm?
What types of DC motors are mentioned in the notes? Shunt, series, compound, or stabilized shunt motors.
What is the significance of the slip frequency in squirrel It is the frequency that induces current in the rotor winding.
cage induction motors?
What is the relationship between torque and horsepower hp = [2π(rpm)(torque)]/33000.
for motors?
What are the two methods of connecting one primary Two ways of connecting for two synchronous speeds in the ratio of 2 to 1.
winding in multiple-speed squirrel cage induction
motors?
What is the total number of synchronous speeds for two Four synchronous speeds.
primary windings with two speeds in the ratio of 2 to 1?
What happens to the motor current in a variable voltage The motor draws high current throughout the speed range.
control system?
What is the peak current and heat dissipation requirement It occurs at approximately two-thirds rated speed and load.
for a variable voltage control system?
What is the approximate full load speed for normal-slip The speeds are approximate and may vary for motors of special design.
motors according to the table?
What is the purpose of external resistors in wound-rotor To adjust motor speed, starting current, and other characteristics.
induction motors?
