Motor Controls Pt1

69 cards   |   Total Attempts: 182
  

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What are the 2 main functions a motor controller preforms.
To disconnect the electrical power and protect a motor from an overload condition.
Common examples of fractional horsepower motors are...?
Exaust fans, garbage disposals, blower motors, small pumps, small drill presses.
What material is used for the surface of motor contacts and why?
Silver Cadmium has good conductivity and a long contact life
Normal motor operation consists of what 3 stages?
Resting, starting and operating under load.
What happens when a contact is opened under load?
An arcing occurs.
What is a magnetic motor starter?
An electromechanical device that provides a means of starting and stopping a motor.
Why is a magnetic motor starter not required to be located in close proximity to the machine operator?
Because pilot devices allow the starter to be located where it poses no danger to the operator.
List 4 examples of processes controlled by magnetic motor starters...
Conveyor systems, pumping operations, packaging systems, paint booths and chemical mixing.
Why is it preferable to use a control voltage that is derived from the motor voltage?
Because both control and motor voltage will become de-energized when the motor controller disconnect is opened.  
List 8 common control voltages...
24, 48, 120, 220, 208, 277, 480, 600
Addtion to main motor contacts other contacts are known as what?
Auxiliary contacts and electrical interlocks
Configurations available for auxiliary contacts are what?
N/O, N/C and combinations of both.
The word "normally" means?
It refers to the condition of the contact in a "power off" or "de-energized" state.
What is the difference between a contactor and a motor starter?
A motor starter has overload relays.
What is the main function of an overload relay?
To protect the motor winding from excessive heat caused by overload currents.