It would appear that something is impeding the return side of the belt. Have you checked the following?

• The tail pulley is free to rotate and no material buildup on the pulley or lying on the belt.
• all other pulleys on return side are free to rotate.
• The belt is not rubbing on the conveyor frame any where along the return side.
• the belt has been trained properly.
• inspect all splices for damage or separation.

If the obvious has been checked out and nothing found. I would strongly consider having a professional person review your system and troubleshoot the problem. ■

Dear Mr.Ankit,

In addition to Mr.Gary's advice, I would suggest to check the take-up mechanism. Is it freely moving ? What is the recommended counter weight & and what is the present weight ? Please post your observations and how the problem is rectified. That will be a learning for me.

Regards, ■

Dear Mr Ankit,

The problem is almost certainly the belt turnovers. I have experienced this problem before and unless they are maintained particularly the alignment through the turnover they create additional frictional restraint during start-up so this is where I would be focussed

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Originally Posted by Ankit Pandey

Hello everyone.

Our company has a 14km (8.7mi) long overland conveyor for transporting coal from the mines for our thermal power plant. Details of the belt are:

Length- 14km(8.7mi), width- 1800mm(70.87in),

drive- 3 motors (+1 standby) in 2 drive pulleys at head and 1 motor (+1 standby) at tail,

Max speed- 5.6m/s (18.3ft/s), max feed rate- 4500tph

Speed variation- using separate VFDs for each motor

Carrying side trough- 45°, Return side trough- 15°

Takeup- horizontal pulley with vertical counter weight

Two belt turning stations

The belt was running smoothly for a year but has suddenly started to sag on the return side when starting. The sag is so severe that the belt begins to fall at vertical section of belt turning station at head. We've tried adding more counter weight which seemed to solve the problem for 2 weeks but the problem is back again.

Please help me in solving the problem. Thanks in advance.

NOTE: 1. The belt regains its tension once it is stopped.

2. We used to run the belt at 4.0m/s. The max speed was not yet achieved.

Typical Overland Belt Conveyor

(courtesy Overland Conveyor Co., USA)

Originally Posted by Gary Blenkhorn

It would appear that something is impeding the return side of the belt. Have you checked the following?

• The tail pulley is free to rotate and no material buildup on the pulley or lying on the belt.
• all other pulleys on return side are free to rotate.
• The belt is not rubbing on the conveyor frame any where along the return side.
• the belt has been trained properly.
• inspect all splices for damage or separation.

If the obvious has been checked out and nothing found. I would strongly consider having a professional person review your system and troubleshoot the problem.

Originally Posted by sganesh

Dear Mr.Ankit,

In addition to Mr.Gary's advice, I would suggest to check the take-up mechanism. Is it freely moving ? What is the recommended counter weight & and what is the present weight ? Please post your observations and how the problem is rectified. That will be a learning for me.

Regards,

Originally Posted by Ankit Pandey

Dear Gary, thank you for your valuable feedback. The situation of belt rubbing with the frame may be our problem as there are few such places where the belt rubs. Rest all points are OK.

Originally Posted by Ankit Pandey

Dear Mr. Ganesh, we have visually checked the movement of take up weight during startup and found that it moved freely.

I am not sure about the recommended counter weight but the current weight is now 71 metric tonnes (was 64 tonnes before the problem occurred).

Give me few weeks to post the observations.

Thanks and regards.

Originally Posted by Colin Benjamin

Dear Mr Ankit,

The problem is almost certainly the belt turnovers. I have experienced this problem before and unless they are maintained particularly the alignment through the turnover they create additional frictional restraint during start-up so this is where I would be focussed

Cheers

Colin Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com

Originally Posted by Roland Heilmann

Hello Mr. Ankit,

on the notion of "suddenly" I'd propose to find out, what was done at that point in time at the conveyor, have there been any maintenance works carrried out or electrical re control overhaul activities?

What about co-ordination of head to tail drive control? Is there a time lapse in start-up sequence?

If the head drives can pull out a significant length of belt, this has to come from somewhere. What is the (change in) behaviour of the take-up counterweight?

What about elongation of the belt?

Regards

R.

Originally Posted by Ankit Pandey

Mr. Gary, your suggestion that the belt rubbing on return side being the problem may be correct as there are few places where the belt rubs with the frame. We would see to it immediately.

Other points were checked and have been found OK.

Thanks for your advice.

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

As much as I despise overland conveyors, and open top gondola unit trains for coal and iron ore

and their net <50% efficiency-

Adding to the excellent points from my friends on the forum:

When was the last time any stretched belt was cut out of the belts in both flights????????????????????????????

Are you using Hot vulcanized splices or mechanical splices???

When was the last time the rails on the counter weights were examined??? Any dirt accumulation binding the vertical weight cage/saddle??

When was the last time the counterweight cables were oiled??? Counter weigth pullies greased?????????????????????

Are you sure your not overloading the belt and the belt is stretching as a result?????????????????

Are you using a Dutchman at the splices??? ■

Dear Me.Leon Zaharis,

For such a long conveyor, I assume that this conveyor must be steel cord belt only and cannot be fabric belt. In that case, is mechanical splice done on steel cord belts ?

I have not heard, mechanical splices of steel cord belt. Please enlighten me. Also what is the meaning of using Dutchman at the splices ?

Thanks a lot in advance and many regards, ■

As Joe mentions, there are far too many Owners and Contractors prepared, anxious even, to discard the review and then run around looking for cheap and cheerful remedies on forums such as this. It is a sign of the times.

On the one hand it provides amusement and on the other hand it might provide modification work for someone. Most of the blame for this is down to the Main Contractor who recognises a plump incompetent Client. My last 3 assignments involved a large French oil & gas contractor who was painfully ignorant about solids handling and mining. These projects also involved equally ignorant Owners who were happy to lavish funds on a Contractor who advised them he was playing safe while both parties knew they both hadn't got a clue what they were about. Eventually those parties admitted this to me but that didn't stop them throwing their shareholders brass around like the proverbial armless Scotsman.

Larry has mention earlier involvement on this job, probably recognised the pitfalls and has the remedy. However if they didn't comply last time they certainly won't comply next time round, especially if the upper management is breathing down their necks and the remedy isn't going to be cheap. Not if you have to take the arterial conveyor out of service......should have gone to Scania Vabis?

All the Owner sould do is read the review and act on it. Asking for free remedies to an expensive problem will not be going anywhere, especially when it is of one's own volition (I nearly said making). If the Owner knows his onions he can recognise the discrepancies and comply with the review findings.

This horse has certainly bolted and even if it is caught and stabled up the animal (28km of expensive belt) is prematurely destined for the knacker's yard. Still fauna-logically: let sleeping dogs lie. ■

Originally Posted by Joseph A. Dos Santos

I have seen it far too often where a design audit is bought and paid for, the audit report points out real issues, and the company that purchases the audit completely ignores the audit report.

You have got it right Joe. I personnally have have audited many conveyors and given the client an expensive report due to botched installations and / or badly maintained and operated systems. Each time I was thanked for such an honest appraisal of the issues found but as always, primarily from the 'Bean Counters' and the senior management 'Saving Face', decided that few, if any of the recommendations be implemented. Senior management were found to have moved on shortly thereafter leaving the mess and grossly non-viable maintenance and repairs to the new management. Unfortunately, the 'Bean Counters' just seem to hang around corrupting the financial systems and unfortunately, they hold too much sway and power within the company.

Generally speaking, the 'Bean Counters' should shoulder the failures due to their non-mechanically ineptness and only look at the cheapest options which, I think most of us know and understand, that if you buy and use 'Crap' equipment and components, you just throw money down the 'Proverbial Gurgler'.

I hope the starter of this thread reads the comments and appreciate's the realities that we are not the final solutions content for their misfortunes but just we give our knowledge freely. I hope the thread starter gains the courage to look at the commercial realities of the disaster he has inherited and works hard to correctly apply a list of basic remedies in the right direction until the system is workable as required. He has to have the fortitude to do what is needed and as Roland Heilmann says, the senior management have to take the necessary actions without 'Shooting the Messenger'.

Rg

Les ■

Mr. Pandey,

As you know I have questioned the idea of winging it in the field, especially in the case of such a significant installation. You say that you are working with NHI (I assume this is your supplier) and you have not made any significant modifications, only the increase of the belt tension, which solved the problem. Increasing belt tension to eliminate a slack belt condition is a significant change, especially since, according to your account, it operated properly in the beginning with the original tension setting. Was this increase in belt tension at the recommendation of NHI after their analysis? What were the analysis and findings that led to the tension increase?

Joe Dos Santos ■

Originally Posted by Ankit Pandey

Here are the things i have to say...

First, i never thought that the descriptions of the system make it so obvious that it can be specifically pointed out. I agree i have been stupid in doing so. I just wanted to know whether this problem was observed some place else or not and if observed then what was its solution. It was for my own knowledge.

Let me be clear that, in no way, i am questioning the work of CDI or NHI. As far as Mr. Nordell knowing me, i am way down at the bottom of the pyramid to be known or heard by anyone except a dozen or so.

I would like to correct Mr. John Gateley on his comment that the NHI have walked off the scene. The NHI personnel have been with us throughout the problem thinking out a solution along with us.

As to what steps did we carry out as solution. Nothing else, after we had added the counterweight the belt is running OK and we are able to feed ALL of our units without compromising in the power generation.

Let me learn about the drive synchro before I post something here. There are still several gaps which need to be filled.

Thanks for all the replies.

Ankit

===============================================

I have personal experience with about a dozen OLC installations, which have degenerated in performance, in a similar fashion to your 14 km from long term use. We are looking at one now. Often the problem has a combination of sources, which the original designers did not foresee and use guess work techniques to correct. ■

Hello,

Earlier respondents have already given good information. I draw attention to the following points which will help the respondents to give their opinion better:

1) How old is the conveying system that is since how many years it is in operation ?

2) As you said, system is designed for 5.6 mps, but up till now you were operating at 4 mps. Has your problem started after exceeding the 4 mps speed or it is occurring while running at 4 mps only ?

3) Location of gravity take-up from head end that is take-up distance from head end.

4) Have you made any replacement or adjustment (setting) in the drive system starting characteristics ?

5) As you say, the problem occurs during starting. Does this imply that conveyor is running properly during steady running and stopping ?

6) If conveyor is running properly during steady and stopping phase, then it will imply something is not proper during starting.

7) Whether this problem started after replacing the rollers and whether the problem started after changing complete idler sets.

8) Is there any sudden change in power consumption during steady state operation of the conveyor and also the individual motors ?

9) Whether this problem is occurring while operating the conveyor at capacity, same as before.

Regards,

Ishwar G. Mulani

Author of Book: Engineering Science And Application Design For Belt Conveyors (new print November, 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 ■

Hello,

I missed two useful points in my earlier post. Please also clarify following two points:

10) Whether the belt excessive sag occurs near head end or tail end or at both the places.

11) Your drive system may have range for choosing the starting time. If it is so, then try to increase starting time by 20%, 30% etc. for few trials and see results. In general, increasing the starting time moderates the forces during starting phase and therefore should be harmless. However take consent from the conveyor designer / supplier and VVVFD supplier prior to doing this. Needless to say that you will be acting at your own responsibilities.

Regards,

Ishwar G. Mulani

Author of Book: Engineering Science And Application Design For Belt Conveyors (new print November, 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 ■

Dear Mr.Ankit,



I believe Mr. Roland Heilmann has a correct scenario to find what has happened to cause this issue to manifest itself which is usually not a quick happening, unless some change in operation or a maintenance maintenance change has been undertaken.

I have always taught my servicemen and others to look at the basics and what occurred prior to the issue being created.

(a) Follow your 'paper trail' back for the previous couple of months prior to the failure and assess all work and operational changes, (HOWEVER SMALL), and go back to the last real known correct running operation.

(b) This issue appears to be a lack of correct logical paper work and monitoring systems and digital data program monitoring applications(Apps), eg:SAPS, MIMS etc. as the issue would not have arisen.

(c) Remember the 'Adage', "When ever any change in One(1) parameter of a belt conveyor is changed, you MUST reassess the whole conveyor parameters to be completely confident that the changes leave the conveyor in a 'Fit For Purpose' operation."

PARAMETER LEGEND = (i) Design (ii) Mechanical componentry (iii) Selection Data Criteria (iv) Quality overall of each of the preceding [(i) to (iii)] (v) Climatic conditions

NOTE:- Adding a 11% more counterweight was not a solution and one I definitely would NOT have undertaken as I have seen many instances where this has caused more issues than I would care to talk about here on the forum.

If you cannot find the true causation, then you must consult a competent conveyor professional.

Please keep the Forum informed of the results and also the rectifications undertaken to get a reliable operating belt. ■

Dear Mr.Ankit,

Please check with electrical or instrumentation engineers also, whoever responsible to maintain VVFD and PLC of the drives of this conveyor.

Were the Master and Slave drives interchanged, prior to this problem?

Was any shutdown jobs carried out by thhose engineers ?. If yes, what were the jobs done by them?

Were the motor RPMs or torque parameters ( if any ) of the drives altered ? Was the time delay while starting , between the drives altered ?

If critical parameters changed, there could be change in the running behaviour of conveyor. Kindly check & post your findings.

Regards,

S.Ganesh ■

Originally Posted by Ankit Pandey

.....I would like to correct Mr. John Gateley on his comment that the NHI have walked off the scene. The NHI personnel have been with us throughout the problem thinking out a solution along with us.

As to what steps did we carry out as solution. Nothing else, after we had added the counterweight the belt is running OK and we are able to feed ALL of our units without compromising in the power generation.

Let me learn about the drive synchro before I post something here. There are still several gaps which need to be filled.

Thanks for all the replies.

Ankit

Consider Eur Ing John Gateley C Eng duly corrected. Further I would point out that if NHI were thinking about a solution 'along with us' then either NHI or your misbegotten colleagues put excessive tension into the belt. Who precisely was it?

When you say the belt is running OK I don't believe it and neither will most respondents hereabouts. Learning about the drive control is rather late in the day, as Mohandes has already broached, and anyway wasn't that what other large parties were supposed to do earlier?

This thread is shifting around like the sands of the desert and if nobody is going to come clean it needs to be put to bed.

Merry Christmas. ■

Originally Posted by sganesh

Dear Mr. Leon Zaharis,

For such a long conveyor, I assume that this conveyor must be steel cord belt only and cannot be fabric belt. In that case, is mechanical splice done on steel cord belts ?

I have not heard, mechanical splices of steel cord belt. Please enlighten me. Also what is the meaning of using Dutchman at the splices ?

Thanks a lot in advance and many regards,

======================================================================

A steel cord belt needs to be hot vulcanised due to its construction.

On a fabric woven belt the dutchman at a mechanical splice allows the

belt to pass over the head pulleys/snubber pulleys/tail pulleys with out

putting excess stress on ends of the mechanical splices

A right angle triangle of belt is cut away from the four corners of the two ends of the belt

to be spliced and the mechanical splice is cut into the belt to connect both ends

of the splice together. ■

Originally Posted by Ankit Pandey

I've posted three replies but none of them is showing up on the thread but is getting posted as can be seen by the multi quote.

This thread is now on page 4 and all of your other posts are on pages 1 & 2 - you can select page numbers at the top right and bottom right side of any page. If you are experiencing problems not seeing your posts on the other pages please let us know.

Gary Blenkhorn

Forum Moderator ■

Dear Mr. Ankit

Greetings...

Hope this is for Reliance Sasan Unit. Correct me if I am wrong.

Would like to know

1. Who is the belt manufacturer.

2. What is the belt modulus as per calculation given by conveyor designer.

3. Is anybody witnessed the internal test values of modulus of elasticity, percentage elongation at suppliers fecilities. If not I suggest you to carryout belt elongation test once again through a competent testing authority.

Thanks

Manoj kumar

Originally Posted by Ankit Pandey

Hello everyone.

Our company has a 14km (8.7mi) long overland conveyor for transporting coal from the mines for our thermal power plant. Details of the belt are:

Length- 14km(8.7mi), width- 1800mm(70.87in),

drive- 3 motors (+1 standby) in 2 drive pulleys at head and 1 motor (+1 standby) at tail,

Max speed- 5.6m/s (18.3ft/s), max feed rate- 4500tph

Speed variation- using separate VFDs for each motor

Carrying side trough- 45°, Return side trough- 15°

Takeup- horizontal pulley with vertical counter weight

Two belt turning stations

The belt was running smoothly for a year but has suddenly started to sag on the return side when starting. The sag is so severe that the belt begins to fall at vertical section of belt turning station at head. We've tried adding more counter weight which seemed to solve the problem for 2 weeks but the problem is back again.

Please help me in solving the problem. Thanks in advance.

NOTE: 1. The belt regains its tension once it is stopped.

2. We used to run the belt at 4.0m/s. The max speed was not yet achieved.

Typical Overland Belt Conveyor

(courtesy Overland Conveyor Co., USA)

■

Dear Ankit,

would you please explain how 3 motors synchronize? ■

Originally Posted by pappu

Dear Mr. Ankit

Greetings...

Hope this is for Reliance Sasan Unit. Correct me if I am wrong.

Would like to know

1. Who is the belt manufacturer.

2. What is the belt modulus as per calculation given by conveyor designer.

3. Is anybody witnessed the internal test values of modulus of elasticity, percentage elongation at suppliers fecilities. If not I suggest you to carryout belt elongation test once again through a competent testing authority.

Thanks

Manoj kumar

=============================================================================

Not an elastic modulus problem.

Conveyor Dynamics, Inc. (CDI) was a Reliance design auditor for the system. We have a good idea of the problem and its solution. The solution is not trivial. If you wish you can contact us for assistance:

Mr. Lawrence Nordell or Mr. Andrew Jennings.

phone: USA 360-671-2200 8-5 M-F

Nordell Cell 360-201-1237 24/7 ■

I am amazed that on an overland conveyor of this significance that professional (paid) help has not been sought. The idea of reactively, blindly adding counterweight is absurd. The system was not designed for your new configuration. It must be restored to its original designed as this worked properly until "the incident". Drive control seems especially suspect. In any case you need professional help. As a first try you should seek that help from the supplier of the overland conveyor.

Joe Dos Santos ■

Originally Posted by Joseph A. Dos Santos

I am amazed that on an overland conveyor of this significance that professional (paid) help has not been sought. The idea of reactively, blindly adding counterweight is absurd. The system was not designed for your new configuration. It must be restored to its original designed as this worked properly until "the incident". Drive control seems especially suspect. In any case you need professional help. As a first try you should seek that help from the supplier of the overland conveyor.

Joe Dos Santos

===========================

Joe,

Reliance Energy (RE) awarded the contract to NHI, a large Chinese turnkey supplier. NHI hired Overland Conveyor Company (OCC) as their design consultant. As previously stated, RE hired CDI as their design auditor. CDI completed our design audit some time before the system fabrication was started. We did offer to participate in the commissioning phase, and did some post-audit support, but not commissioning.

The conveyor is equipped with a LRR rubber bottom cover.

I do agree with your perception on how a resolution to the problem is proceeding. A very large and complex system, with many features, to toy with. Looks like some in client's employ are fishing for a solution they do not understand. I do not know the author of this thread or his capability to go much beyond the present discussion points.



n ■

Roland,

Very well said. This system is far too important and too expensive to be wining it in the field.

Joe Dos Santos ■

Sorry for the typo. The word is "winging" not "wining", which means trying ill advised solutions in the field with the hope that it will work but having no actual basis to believe it.

Joe Dos Santos ■

Whatever the obvious reason for the development of excessive return side slack surely the better modification would have been to remove the turnover in the first place rather than to overload the counterweight.

I reckon that's what Graham would do too. There is little justification for turning a belt over unless you intend to make use of the top cover in the returning direction....or what?

"There's clearly a giant unbridged trench between the supplier / consultants / auditors and the op. & maint. staff of the system."

This is heavy engineering so nothing new there. ■

Originally Posted by Roland Heilmann

@ whoever takes interest

I most strongly recommend the estimated thread starter to follow the advice of Mr. Dos Santos.

Sorry to say, but the information given show a development not to be expected on a professional level. There's clearly a giant unabridged trench between the supplier / consultants / auditors and the op. & maint. staff of the system. This needs i.m.o. the immediate attention of the resp. management.

Even if for some (?) reason plain names are given here some conclusions spring to the eye & i'd dare to speak some out:

a) It is clearly to be understood from the words of the responsible design auditor, that the readjustment / restoration to normal operational conditions of the conveyor needs professional support on this very same level (design / design auditing).

b) A sufficient training and educational programme for all staff involved with op. and maint. of the conveyor system is urgently !!! required.

c) There's NO WAY that professional advice from this forum should be taken as sole remedy and base to major interventions into running systems without sufficient professional understanding of the system by the persons dealing with the system.

d) There seems to be a major cultural difference between the parties involved, where for the sake of the overall good (functioning / operation / professional confidence, ...) there should be a safe common ground at least for open and objective technical communication.

e) I fear to conclude that after one year no professional support is regularly available to the "end - user", the more that the system seems not yet to be running at final stage parameters.

f) A malfunction report w/o mentioning the call for warranty support sent out could lead to the conclusion that the system underwent changes / operation which were / was out of specified limits (hence the question about what was changed before the malfunction occurred).

I would consider (at least very seriously so) to take the system out of operation until the basics were sorted out and the faults straightened.

What do others think about this?

Regards

R.

Well Done.

I believe Roland has stated the facts that we should aspire to emulate. One thing I am bewildered at in all the responses previously posted is covered in Roland's item (e) That the system does not appear to have been commissioned covering the full range of operational 'Fit For Purpose' full criteria of parameters of speed and load factors and all other sundry operating scenarios. It is not normally left to the Client to complete the commissioning schedule.

No confirmation of the final commissioning has been posted as having been completed.

Les Dunn ■

Originally Posted by nordell

===========================

... NHI hired Overland Conveyor Company (OCC) as their design consultant. As previously stated, RE hired CDI as their design auditor. CDI completed our design audit some time before the system fabrication was started.

I have said before that I would not buy a nail from NHI and I still wouldn't. It all sounds like NHI cut corners with the design after the audit. After realising that they were in the manure they appear to have walked off the job and left the Owner to finish it. If the Owner had insufficient knowledge to control the job in the the first place he had as much chance as snowball in hell of correcting the Chinese puzzle he lumbered himself with. But he tried and, in the process, really messed up.

Now Mr Thread Starter, it seems like you are new on the job since Larry Nordell didn't know you first time round. In that case you are strongly recommended here and in other replies to restore the belt to its original state. I further recommend that you then take internal issue with your colleagues to find out why the counterweight was increased and then look for discrepancies between what you should have bought and what was actually bought.

Do this while future employers are looking at your CV. Your present employer is prepared to engage a cheap nasty outfit to build his plant so he is hardly likely to shower his engineers with rewards. We get this situation quite regularly on this forum and no doubt the situation will outlive many of us.

For technical finale I would like to reiterate Mohandes request for some explanation of the drive synchronisations. After all it does seem a most plausible issue. ■

I have seen it far too often where a design audit is bought and paid for, the audit report points out real issues, and the company that purchases the audit completely ignores the audit report. ■

Originally Posted by johngateley

Consider Eur Ing John Gateley C Eng duly corrected. Further I would point out that if NHI were thinking about a solution 'along with us' then either NHI or your misbegotten colleagues put excessive tension into the belt. Who precisely was it?

When you say the belt is running OK I don't believe it and neither will most respondents hereabouts. Learning about the drive control is rather late in the day, as Mohandes has already broached, and anyway wasn't that what other large parties were supposed to do earlier?

This thread is shifting around like the sands of the desert and if nobody is going to come clean it needs to be put to bed.

Merry Christmas.

I agree with Sir. John!

I think I have in-depth information about this particular OLC and problems associated with it which keep on recurring. All credit goes to NHI and hoax behind their so called expertise in Bulk Material Handling.

Leaving such a costly infrastructure (which directly affects thousands of MW of Generation of Power plant) dependent on "HIT-AND-TRY" is not acceptable. if even the designer (NHI) is unable to recognize the root cause then it raises a big question mark on their expertise and exhibits lack of expertise.

To further enlighten NHI quality & standards right from Designing, Civil, Mechanical, Electrical, Instrumentation, Erection, Commissioning, Equipment quality, O&M etc... you name the area/phase and debatable loop holes are uncountable.

Once again, I request Senior Admin to Clean it or please put it to bed. ■

Have you considered the start up time is off. If the Start up time of the system is too fast if could be adding extra slack to the belt and creating a wave.

Try to measure the start up time until it reaches full speed . The belt ran okay in the beginning but perhaps the start up time has changed ■

Hello,

Earlier respondents have mentioned checking for many items, probable causes and suggestions. I add to check for following:

1) Such thing can happen if the belt has stretched (increased in length) and thereby take-up effective stroke has become inadequate. See that take-up is not reaching dead end during conveyor start-up.

2) See that drive start-up motion is occurring gradually and reaching full speed as per design time, without exceeding peak torque limitation. If this is not so, then it can result into belt lift-up / shift at curves and excessive released length of the belt. Your conveyor photograph shows vertical and horizontal curves, and possibly these will be large in numbers considering 14 km conveyor length. The drive pulley speed-up should appear consistent without unusual symptom. Also see that someone has not tempered inadvertently with the drive operational logic control unit’s setting during maintenance or these items have become unhealthy. These could be items of scoop coupling or VVFD drive. The take-up movement during start-up should not be jerky. Whether its behaviour is same as before the present problem.

Ishwar 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 ■

If the conveyor is with horizontal curvatures, take up tension is kept minimum to avoid belt sway at gallery curvatures. To avoid belt damage due to sagging and subsequent rubbing, it is advisable to lower 90 degree turning pulley sets. ■