Types and Characteristics of Load Torque

Classification of load torques :

1.Active Load torques

2.Passice Load torques

Active Load Torques:

Load torques which have the potential to drive the motor under equilibrium conditions are called active load torques.

Load torques usually retain sign when the drive rotation is changed.

Active Load Torques

Passive Torque:

Load torques which always oppose the motion and change their sign on the reversal of motion are called passive load torques.

Torque due to friction cutting – Passive torque.

Components of load torques:

1.Friction Torque (TF)

The friction torque (TF) is the equivalent value of various friction torques referred to the motor shaft.

2.Windage Torque (Tw)

When a motor runs, the wind generates a torque opposing the motion . This is known as the winding torque.

3.Torque required to do useful mechanical work ( Tm)

Nature of the torque depands of type of load.

It may be constant and indeoendent of speed, Some function of speed, may be time invariant or time variant.

The nature of the torque may change with the change in the loads mode of operation.

Characteristics of different types of load:

In electric drives the driving equipment is an electric motor.

Selection of particular type of motor driving a m/c is the matching of speed-torque charal of the driven unit and that of the motor.

· Different types of loads exhibit different speed torque charal.

· Most of the industrial loads can be classified into the following 4 general categories:

1. Constant torque type load.

2. Torque proportional to speed (generator type load)

3. Torque proportional to square of the speed (fan type load)

4. Torque inversely proportional to speed (const power type load)

1.Constant Torque Characteristic :

image

The speed – torque characteristic of this type of load is given by T=K.

Working motor have each mechanical nature of work like shaping , cutting, grinding or sharing, require constant torque irrespective of speed. Similarly cranes during the hoisting.

Similarly cranes during the hoisting and conveyors handling constant weight of material / unit, time also exhibit this type of characteristics.

Torque proportional to speed:

image

Separately excuted dc generators connected to a constant resistance load, eddy current brakes and calendaring m/cs have a speed torque characteristics m/cs have a speed – torque characteristics given by T= Kw.

Torque propositional to square of the speed :

image

Load Torque Square of speed

Example : Fans , Rotary pumps , compressors , ship propellers. The speed – torque characteristics of this type of load is given by

Torque inversely propositional to speed:

image

· In such types of loads , torque is inversely proportional to speed or load power remains constant.

· Eq: Lathes, boring m/cs, milling m/cs , steel mill colier and electric traction load.

· This type of characteristics is given by

· Most of the load require extra effort at the time of starting to overcome static friction. In power application it is known as brake away torque and load control engineers call it “stiction” . Because of slition , the speed torque characteristics of the load is modified near to zero speed.

6 comments:

  1. I was reading some of your content on this website and I conceive this internet site is really informative ! Keep on putting up. digital torque wrenches

    ReplyDelete
  2. Cool stuff you have got and you keep update all of us. best instagram followers app free

    ReplyDelete
  3. Keep in mind that torque wrenches may round or crack cheaply made sockets, so be sure to use a high quality socket set to avoid any issue. More info at torquewrenchguide.com

    ReplyDelete
  4. Nonetheless, this exactness can undoubtedly be lost if the wrench isn't reset to zero preceding stockpiling. Bar wrenches don't have this chance of losing their precision, however are less exact right out of the crate. https://torquewrenchguide.com/reviews/neiko-torque-wrenches/

    ReplyDelete
  5. Nice post! This is a very nice blog that I will definitively come back to more times this year! Thanks for informative post. link: Digital Torque Wrenches

    ReplyDelete
  6. Thank you so much for such an wonderful blog. I’m really thankful to you for this informative article.Camel Safari In Jaisalmer Lovely blog

    ReplyDelete