Reverse engineering on this scale can be confusing.

What happened to belt speed?

If the belt wasn't slit or worn down to the carcass there would be no need to ask. Just look at the stamps on the return side which are supposed to be embossed on the edge at certain intervals which I have forgotten. ■

I am not an expert, though:

If you can advise the desired outcome, it may assist the forum providing responses.

Assuming for whatever reason(s) you are unable to verify the physical installation, other options may include:

1.Site maintenance [or whoever looks after the infrastructure] records.

2.If the infrastructure is managed by a subcontractor, consider corresponding with them.

3.Maybe it is possible to have a / the belt supplier / someone suitable to inspect the installation, and advise with [some] certainty.

Though to answer your question, I propose yes, either:

1. Complete an assessment as required [based on profile etc], or:

2. An estimate could be made, subject to various assumptions, and based on the installed power, assuming you know some other fundamental properties, including: installation conditions [to select: safety factor, and friction coefficient u unitless], profile [angle of wrap 0 rad], and belt: speed (m/s), and width (m).

Though you must confirm: such an estimate is suitably accurate for your current question, and the validity of the assumptions.

For a single drive conveyor [though it is possible to complete corresponding calculations for other arrangements]:

1. P = Te*S.

2. Rearranging 1:

Te=P/S.

3. T1-T2=Te

4. Rearranging 3:

T1=Te+T2

5. T1/T2 = exp(u0).

6. Rearranging 5, and substituting 4:

T2=Te/(exp(u0)-1)

7. Rearranging 3, and substituting both: 2, and 6:

T1=(P/S)*[(1/(exp(u0)-1)) +1]

Then though applying a safety factor, and knowing the belt width, you could select a belt rating.

You could refine this model if you knew the active [mechanical] power [from site i.e. MPR / PCS / SCADA etc] in lieu of installed power.

Various assumptions that were made to create this model, including:

1.The original designer, or subsequent operator etc has not selected a larger motor / belt rating for rationalisation [or depending on the application, just to hold the material without excessive sag etc] etc.

2.The original designer used the same friction coefficient as you select.

3.Starting / stopping cases etc do not govern the selection, though again subject to various assumptions, you could complete a similar assessment.

Regards,

Lyle ■

Originally Posted by sganesh

Dear Mr.John,

Designing of Motor KW includes the belt speed also, I beleive.

Normal procedure for embossing the belt specification & batch number is at every 10 meters.

Regards,

Whether you believe it or not, there is absolutely no relationship between motor power and belt speed in the text you presented.

But since the stamps are at 10 metre intervals, thanks for that, you can read the required information on any belt, unless the pulley centres are less than about 4 metres. ■

Hello,

As said by earlier respondents, motor kW (actually consumed kW at drive pulley/s) alone is not adequate to decide conveyor resistance force (or tractive pull). One also needs the conveyor speed because the applicable equation has this parameter.

Consumed kW = (Resistance force R in Newton) x (Speed mps) ÷ 1000

Therefore (Resistance force R in Newton) = (Consumed kW) x (1000) ÷ (Speed mps)

Now resistance ‘R’ can enable to decide belt tension T1 but it will vary case to case depending upon: A) One pulley drive, B) Multiple pulleys drives, C) Wrap angles, 4) Friction coefficient between belt and pulley/s, 5) Type of take-up, etc.

Furthermore, the starting tension T1s will be influenced by: 1) DOL starting 2) Gradual starting (type of fluid coupling or VVFD setting).

As can be seen, practically meaningful T1 and T1s are result of many parameters, where kW is one among many. So, kW alone is not adequate to decide T1 and T1s and thereby we cannot decide belt rating, because minimum belt rating is nothing but these tension values multiplied by applicable safety factors.

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 ■

You are now trying to move the goalposts as usual. However the rules of Association Football cover such eventualities because the posts have only been altered once since the Founders sat down in the Freemasons' Tavern in Great Queen Street, where the FA was formed on October 26, 1863, and wrote it all down for the world to see how the game should be played properly.

Motor starting torque is quite irrelevant in your context. Belt safety factor covers the issue.

Let's face it: it doesn't call for a rocket scientist to look for the stamp and read it. ■

Dear Ganesh,

I think that an electric motor, when starting DOL, always peaks at 6 to 7 I-nominal or even higher.

Then, I assume that the starting period of a fully loaded conveyor takes more than a few seconds.

During the starting period, the slip frequency of the e-motor is high, causing a low powerfactor.

This means that the power in kW, delivered during the start-up is very low in combination with the not fully developed rpm.

Using the delivered kW for your calculation is wrong.

As John already indicated, you ignored Newton’s laws, (Force = mass*acceleration and Action=Reaction).

Calculate the equilibrium of the driving torque and the load torque + the acceleration torque as a function of the e-motor rpm and time.

Success ■

For the estimate assessment that I proposed earlier, the power would be the installed motor power, or if you wanted to refine the model the running / "consumed" active power; though all of the assumptions, including in particular assumption 3, are still relevant.

Also there should have been a fourth assumption, viz: the installed countermass reflects the theoretical requirements, and hence it has not been increased for "rationalisation" [or "fault fixing" etc].

I note that if you know the installed countermass / take up arrangement, you could substitute this (T2) into the assessment, in lieu of the theoretical result.

If the inspection type options are not practical, maybe you can find someone locally to assist you with a theoretical assessment.

Regards,

Lyle ■

Dear Sir,

Approximate method generally followed during estimation stage is follows:-

Let P=Motor kW

V=Belt speed

Te=Effective tension

T1= Tight side tension

T1s= Starting tight side tension

T2= Slack side tension

BW= Belt width in metres

Te≈ P x 1000/ (1.1 x V); Normally most of the clients/consultants in india (NTPC, Desein, TCE, Mahagenco, TNEB, Evonik, Mecon,BHEL, APGENCO) asks for a minimum margin of 10% over shaft power for calculating the motor kW. Thats why we are dividing by 1.1.

T1= Te x 1.38 (for 210 degree angle of wrap, the wrap factor as per CEMA is 0.38)

T2= T1-Te

T1s= x Te+T2; (consider = 1.5 for traction type fluid coupling and 1.2 for scoop type fluid coupling)

Minimum belt rating required= T1s (in kN)/ {BW (in metres) x 0.8}; Normally most of the clients in india specify in their contract that "Normal working tension at design capacity is less than 80% of maximum allowable working tension"; That is why we considered 0.8

Select the belt rating based on the above result.

Link for a belt catalogue:

http://www.mrftyres.com/downloads/conveyorbelting.pdf

PLEASE NOTE THAT ABOVE METHOD IS A SHORT CUT TO OBTAIN THE BELT RATING USUALLY USED TO ESTIMATE THE BELT RATING DURING THE TENDERING STAGE WHERE DATA AVAILABLE IS LIMITED. However I have used this many times (only for N-N belts) and found the method to be good enough. ■

What is point of replying when respondents refuse to read the question in the first place......I should ask myself!

The motto for these forums often seems to be: "Ask a silly question and then argue with the answers." But it is fun. ■