Think about the % of fill level in a fluid coupling, the lower the level the more slippage you would have. Slippage decreases the speed of the conveyor thus increasing the material load on the conveyor (assuming a constant feed rate) which in turn increases the amperage of the motor. ■

Agreed.

When all the oil is drained, there will be no torque transmittal at all

Agreed.

Due to the lower oil level, the torque transmission is lower and therefore the conveyor speed reduces.

Agreed.

The conveyor filling will increase, due to the lower conveyor speed.

This statement is not logical.

If the torque transmission from the e-motor reduces and the e-motor rpm stays (almost) constant, the amperage of the e-motor should decrease with the lower torque transmission, caused by the lower oil level.

If a lower oil level leads to a higher amperage, then with no oil at all (completely empty and zero torque transmission) the e-motor consumes the highest current at zero torque as it was stalled.

Remark: A low oil level induces high oil temperatures until a melting fuse drains all the oil to save the installation and unload the e-motor. ■

Teus

I would agree with you if you are at the max torque capacity of the FC when the load on the conveyor increases. But as the conveyor load increases the motor load will increase to the limiting torque of the FC. If the designer designed the system so that it is running at the max torque capacity at normal operating conditions then I would be looking for a new designer.

All the best.

Gary ■

Gary,

Thanks’ for the additional information.

I understand that the FC is transmitting the required torque by the increased slip.

A long as the drive system (e-motor and FC) can deliver the required higher torque for the conveyor, at cost of higher slip (and temperature) the system will operate.

As soon as the oil level becomes too low, the melting fuse should act before damage is done.

Balancing the drive torque curves with the required torque curves until equilibrium, should mr. Ganesh make clear how it works.

The questions of Roland actually belong to the information that should have come with the original thread. ■

Hello,

As explained by Mr. Gary Blenkhorn, the lesser fluid level causes the more slip in fluid coupling which in turn will result into relatively slower speed of conveyor and consequently will result into higher value of material load kg/m and hence more resisting force / torque / amperage.

Please find attached herewith induction motors characteristics graph as an addition to above information. As can be seen more torque by motor also results into more current (both increase simultaneously in the operational speed range of motor).

It is presumed that the question refers to conveyor operational situation wherein oil level decrease is not excessive, conveyor speed reduction is also small value, and thereby zero speed switch (belt monitor switch) has not intervened to trip the conveyor (as per tolerance setting in zero speed switch).

Ishwar G. Mulani

Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 2012.

Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’

Advisor / Consultant for Bulk Material Handling

System & Issues.

Pune, India. Tel.: 0091 (0)20 25871916

Email: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com

Attachments

induction motor characteristic graphs_1 page (PDF)

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