Synchronous Motor Working Principle & Also Purpose Of A Synchronous Motor.
An Electromechanical Device That Transfers Energy From The Electrical To The Mechanical Domain Is An Electrical Motor. We Have Divided The Motors Into Single-phase And Three-phase Categories Based On The Kind Of Input. Synchronous And Induction Motors Are More Frequently Employed Among Three-phase Motors.
An Electrical Field Is Created When Three Phase Electric Conductors Are Arranged In Specific Geometrical Locations (At Specific Angles To One Another).
At This Point, The Speed At Which The Spinning Magnetic Field Rotates Is Referred To As Its Synchronous Speed. When An Electromagnet Is Placed In A Rotating Magnetic Field, It Becomes Magnetically Locked Into The Field And Rotates At The Same Speed As The Spinning Magnetic Field.
The Reason Synchronous Motors Are Named Such Is That Its Rotor Rotates At The Same Speed As The Magnetic Field. Because It Only Has One Speed—synchronous Speed—and No Intermediate Speed—that Is, It Is Synchronized With The Supply Frequency—it Can Be Thought Of As A Fixed Speed Motor.
The Source Of Synchronous Speed Is:-
Synchronous Motor Construction:
Its Structure Is Essentially The Same As That Of A Three-phase Induction Motor, With The Exception Of The Rotor Receiving A Direct Current Supply—the Rationale For Which Is Provided Later. Let's Now Go Over This Motor Type's Fundamental Construction.
The Following Are The Primary Characteristics Of Synchronous Motors:
• They Are Not Self-starting By Nature. Before They Are Synchronized, They Need An External Method To Accelerate To Nearly Synchronous Speed.
• Because Their Operating Speed Is Synchronized With The Supply Frequency, They Perform As Constant Speed Motors Under Constant Supply Frequency Conditions, Regardless Of The Load.
• The Ability To Function At Any Power Factor Is One Of This Motor's Special Features.
Synchronous Motor Operation Principle:
A Synchronous Motor Receives Two Electrical Inputs, Making It A Twice Stimulated Machine. The Rotor Has A Dc Supply, While The Stator Winding, Which Is Made Up Of Three Phase Windings, Is Supplied With A Three Phase Supply. 3 Phase Spinning Magnetic Flux Is Produced By The 3 Phase Stator Winding That Is Carrying 3 Phase Currents.
An Ongoing Flux Is Also Produced By The Rotor That Holds The Dc Supply. The Above Relation Shows That, Assuming A Frequency Of 50 Hz, The Three-phase Rotating Flux Rotates At A Rate Of Roughly 3000 Revolutions Per Minute Or 50 Revolutions Per Second.
The Rotor And Stator Poles May Be Polarized N-n Or S-S At One Moment, Producing A Repulsive Force On The Rotor, And N-S Providing An Attractive Force The Very Next Instant.
However, The Rotor's Inertia Prevents It From Rotating In Either Direction In Response To An Attracting Or Repulsive Force, Forcing It To Remain In A Standstill. It Is Therefore Not Self-starting.
In Order To Overcome This Inertia, The Rotor Is First Given A Mechanical Input That Causes It To Rotate In The Same Direction As The Magnetic Field, Approaching Synchronous Speed. After A While, The Synchronous Motor Turns In Time With The Frequency Due To Magnetic Locking.
Starting Techniques For Synchronous Motors:
• Motors That Are Synchronous Are Mechanically Related To One Another. It Might Be A Dc Shunt Motor Or A Three Phase Induction Motor. Initially, Dc Excitation Is Not Provided. After Rotation At A Speed Extremely Near To Its Synchronous Speed, Dc Excitation Is Applied.
The External Motor's Supply Is Turned Off When Magnetic Locking Occurs After A Certain Amount Of Time.
• Damper Winding: An Extra Winding Is Positioned In The Rotor Pole Face If The Synchronous Motor Is Of The Salient Pole Type. An Induced EMF Is Produced In The Rotor At Its Initial Standstill, When The Relative Speed Between The Damper Winding And The Rotating Air Gap Flux Is Large, Resulting In The Necessary Starting Torque.
Both Torque And Emf Decrease As Speed Gets Closer To Synchronous Speed, And Torque Also Decreases To Zero When Magnetic Locking Occurs.
As A Result, In This Instance, Synchronous Is First Operated As An Induction Motor With An Extra Winding Before Being Finally Synchronized With The Frequency.
Use Of Synchronous Motors:
Synchronous Motors Are Used To Increase Power Factor When There Is No Load Attached To Their Shaft. Because Of Its Ability To Function At Any Power Factor, It Is Utilized In Power Systems When Static Capacitors Are Too Expensive.
• Synchronous Motors Are Used In Situations Requiring Great Power And A Lower Operating Speed (Around 500 Rpm).
The Equivalent Induction Motor Is Very Expensive, Large, And Heavy For Power Requirements Ranging From 35 Kw To 2500 Kw. Therefore, It Is Preferable To Use These Motors.
For Example, Rolling Mills, Compressors, And Reciprocating Pumps.
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