Basic of Motor Control

What is definition of motor control?This is familiar question from electrical person around the world.Motor control is common practice for machine application and industry operation.

Basically motor control definition is to STOP and START the electric motor.Technology and innovation of motor control is always developed to parallel with current application needed.

Motor control have a two basic methods.There is MANUAL control and MAGNETIC control.I describe detail about manual and magnetic control circuit diagram and basic operation.

Motor control definition

1) Manual Motor Control

When first motor were introduced for application,the common control is only basic manual stop and start circuit diagram.

It only have a main switch for stop start operation and fuse for motor protection.This method have disadvantage and not safe to used because as shown circuit diagram below :-

1) Motor operation always done by manually by operator.It not practical and can defected by human error.

2) Not safety when switch the bigger size of electric motor due to high in rush current and must more physical effort to switched.

3) It can be dangerous and can cause accidents due to sudden restarting of motors after power supply restoration.

2) Magnetic Motor Control

This method is common application now due to flexibility,easy to handling and more safety device to protected motor for damage.It used two important component that we call CONTACTOR and RELAY.

With this magnetic component,we can energized a main contact only with small power.It gave more desire to control of machine or equipment.We can control with various operation depend on our application such as stopping,starting,rotation and speed variation.Circuit diagram for magnetic control as shown below :-


3) Advantage of Magnetic Control

1) Provide safety to the user when operated the motor and reduce risk to accidental contact with live conductor or exposed to power arc and flash.

2) No need additional skills to operated the system because it user-friendly.

3) Can reduce breakdown,wear of component and more life span of motor due to we can control a high in rush current and peak.

4) We can design the control with interlocking system for various operation of multi motor drive and can running in automatic sequence for safety purpose.

5) Can integrated with new technology of controlling device such as PLC,DSC,VFD and many more.It make more efficient and easy to operated.


  1. sinnadurai says

    Instead of using line to neutral voltage rated operating coil,what are the advantages of using line to line voltage rated operating coil with a transformer. What is the advantage of dc or ac ELV(24 or 50V)for operating coil(control circuit)/>

    • Hi Sinnadurai,

      Advantage using line to line voltage from transformer.
      1) This is we called ” Insulation power supply”.The advantage is,it safe for electric shock and the voltage is constant and quite clean from noise.It can prolong our contactor coil.

      Advantage for AC and DC supply

      AC Supply
      1) Model for AC supply is available in market,so the price is cheap and easy to get.
      2) Application for Bigger size machine

      DC Supply
      1) It safe from electric shock cause use 24 VDC.
      2) It clean from Noise issue
      3) Easy to combine the control with electronic equipment and PLC module
      4) Size is small and compact.Can design the panel without messy issue.

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