Ramsay Test Motors and Controls

Question 1

What does the abbreviation 'FLA' mean on an electric motor nameplate?

Accepted Answer

Full Load Amperes

Answer

FLA stands for Full Load Amperes, indicating the current the motor draws when operating at rated voltage and rated horsepower output.

Question 2

What is the synchronous speed of a 4-pole AC induction motor connected to a 60 Hz power supply?

Accepted Answer

1800 RPM

Answer

Synchronous speed = (120 × frequency) / number of poles = (120 × 60) / 4 = 1800 RPM.

Question 3

A squirrel cage induction motor gets its name from the design of which component?

Accepted Answer

The rotor, which uses aluminum or copper bars short-circuited at both ends

Answer

The rotor of a squirrel cage motor consists of conductive bars (aluminum or copper) embedded in laminations and short-circuited at each end by end rings, resembling a squirrel cage.

Question 4

What is the primary purpose of the overload relay in a motor starter?

Accepted Answer

To protect the motor from damage caused by sustained overcurrent

Answer

Overload relays detect excessive current sustained over time and trip the starter to prevent motor winding damage from heat buildup.

Question 5

A three-phase motor that was running normally suddenly begins running at reduced speed under full load. What is the most likely cause?

Accepted Answer

One phase of the three-phase supply has been lost (single-phasing)

Answer

Loss of one phase (single-phasing) causes the motor to run on single-phase power, drastically reducing torque and speed while dramatically increasing current draw.

Ramsay Test Practice Test

Ramsay Test Practice Test

Ramsay Test Motors and Controls