Basic Principles of Motor Control - Unit
1 Test correctly answered
Who must be advised that a lockout/tagout procedure is going to be performed? - correct answer ✔✔All
affected employees
What has to be done before lockout/tagout procedures can be implemented? - correct answer
✔✔Identification of hazards to which workers can be exposed.
Which devices may be used to reverse the sequence of three-phase power lines? - correct answer
✔✔Cam switches can be used for that purpose, with the addition of overload protection. (cam switch
and dual contactors)
What is the name of the coil of wire around a soft iron core used to operate magnetic contactors and
relays? - correct answer ✔✔Solenoids are extensively used to operate contactors and control relays.
Placing a coil of wire around a soft iron core sets up a magnetic flux.
What are the two essential components of a magnetic motor starter? - correct answer ✔✔contactors
and overloads (??)
What is the name of the highest current that a device can interrupt at a rated voltage? - correct answer
✔✔The maximum short-circuits current that a breaker can interrupt safely is called the interrupting
capacity.
What components offer protection against a sustained low level of excessive current? - correct answer
✔✔Fuses (Circuit-breakers and fuses protect the motor from very high currents. Overload protection
devices are safeguards against prolonged, relatively high current levels.)
What phenomenon happens immediately after full voltage is applied to start a motor? - correct answer
✔✔Inrush current (When sizing the protection devices, it is important to note that all electric motors
suffer from a condition called inrush current. When starting the motor, there is a brief spike of current
that can be several times the steady-state current.)
1 Test correctly answered
Who must be advised that a lockout/tagout procedure is going to be performed? - correct answer ✔✔All
affected employees
What has to be done before lockout/tagout procedures can be implemented? - correct answer
✔✔Identification of hazards to which workers can be exposed.
Which devices may be used to reverse the sequence of three-phase power lines? - correct answer
✔✔Cam switches can be used for that purpose, with the addition of overload protection. (cam switch
and dual contactors)
What is the name of the coil of wire around a soft iron core used to operate magnetic contactors and
relays? - correct answer ✔✔Solenoids are extensively used to operate contactors and control relays.
Placing a coil of wire around a soft iron core sets up a magnetic flux.
What are the two essential components of a magnetic motor starter? - correct answer ✔✔contactors
and overloads (??)
What is the name of the highest current that a device can interrupt at a rated voltage? - correct answer
✔✔The maximum short-circuits current that a breaker can interrupt safely is called the interrupting
capacity.
What components offer protection against a sustained low level of excessive current? - correct answer
✔✔Fuses (Circuit-breakers and fuses protect the motor from very high currents. Overload protection
devices are safeguards against prolonged, relatively high current levels.)
What phenomenon happens immediately after full voltage is applied to start a motor? - correct answer
✔✔Inrush current (When sizing the protection devices, it is important to note that all electric motors
suffer from a condition called inrush current. When starting the motor, there is a brief spike of current
that can be several times the steady-state current.)
