Re: Starting Problem Of A Belt Conveyor
Is this a new installation and you trying to start for the first time or it is an older installation that you are experiencing a problem?
Has the fluid level in the fluid coupling been set correctly?
Assuming that the motor is 3 phase have you checked for single phasing and secure motor lead connections?
Does the conveyor start to move prior to the trip out?
I also moved your thread to a more appropriate forum. ■
Gary Blenkhorn
President - Bulk Handlng Technology Inc.
Email: garyblenkhorn@gmail.com
Linkedin Profile: http://www.linkedin.com/in/gary-blenkhorn-6286954b
Offering Conveyor Design Services, Conveyor Transfer Design Services and SolidWorks Design Services for equipment layouts.
Re: Starting Problem Of A Belt Conveyor
Is this a new installation and you trying to start for the first time or it is an older installation that you are experiencing a problem?
Has the fluid level in the fluid coupling been set correctly?
Assuming that the motor is 3 phase have you checked for single phasing and secure motor lead connections?
Does the conveyor start to move prior to the trip out?
I also moved your thread to a more appropriate forum. ■
Gary Blenkhorn
President - Bulk Handlng Technology Inc.
Email: garyblenkhorn@gmail.com
Linkedin Profile: http://www.linkedin.com/in/gary-blenkhorn-6286954b
Offering Conveyor Design Services, Conveyor Transfer Design Services and SolidWorks Design Services for equipment layouts.
Checks
Dear Mr. Sandipan Daw,
in addition to prevoius post:
--> Please be most careful at releasing the belt of it's residual tensions!!!
Then:
- You mention checking of all mechanical components, did you loosen the belt as if you would be changing a pulley and then lifted the belt around the pulleys & tried to rotate the pulleys?
- When starting the conveyor, did the drive pulley built up a belt tension (pulling out belt sag)?
- Is tension pulley position at tensioning device as per required setup?
- What changes have been made upon that conveyor in the last time?
- Does the drive pulley have any friction increasing lagging?
- Perhaps a far fetch: With that lift, do you have a low speed holdback somewhere and is rotational direction of drive correct (Phases correctly connected in junction box)?
My reasoning: If the drive pulley could rotate, it would do so perhaps even under a blocked belt if torque overcomes frictional resistance due to belt strain on pulley surface. However, that makes up a dangerous situation as a lot of force might be stored in a stretched belt. The checks for jammed / quenched belt and blocked pulleys should be very thorough, beware of releasing belt strain into drive train --> explosion of fluid cplg at overspeed.
Regards
R. ■
Checks
Dear Mr. Sandipan Daw,
in addition to prevoius post:
--> Please be most careful at releasing the belt of it's residual tensions!!!
Then:
- You mention checking of all mechanical components, did you loosen the belt as if you would be changing a pulley and then lifted the belt around the pulleys & tried to rotate the pulleys?
- When starting the conveyor, did the drive pulley built up a belt tension (pulling out belt sag)?
- Is tension pulley position at tensioning device as per required setup?
- What changes have been made upon that conveyor in the last time?
- Does the drive pulley have any friction increasing lagging?
- Perhaps a far fetch: With that lift, do you have a low speed holdback somewhere and is rotational direction of drive correct (Phases correctly connected in junction box)?
My reasoning: If the drive pulley could rotate, it would do so perhaps even under a blocked belt if torque overcomes frictional resistance due to belt strain on pulley surface. However, that makes up a dangerous situation as a lot of force might be stored in a stretched belt. The checks for jammed / quenched belt and blocked pulleys should be very thorough, beware of releasing belt strain into drive train --> explosion of fluid cplg at overspeed.
Regards
R. ■
Re: Starting Problem Of A Belt Conveyor
Originally Posted by sandipandaw
This could be more of electrical problem. Suggest you take trial only for motor.
Regards, ■
Re: Starting Problem Of A Belt Conveyor
Originally Posted by sandipandaw
This could be more of electrical problem. Suggest you take trial only for motor.
Regards, ■
Starting Problem Of The Motor.
Originally Posted by sganeshRegards,
Dear Sandipan,
Hope it is a cage motor. 650 amps indicate locked rotor-repeated trial will result in motor failure
The Problem may be Power Supply,Motor ,Gear box or the conveyor system.
I suggest the following checks,
1.This may be an LT motor (415 volts),please check the terminal voltages in all the three phase.If it is O.K,rotate the motor alone with hand.
If it is O.K,Start the motor alone,with out fluid coupling.It must run,with a nominal current of 10 to 15% of full load current in all the three phases, if not the motor
may be faulty.
2.Check the fluid coupling and gear box for freeness by hand rotation. If there is a built in hold back ensure it is working for correct direction.
If they are O.K,connect the motor, fluid coupling,gear box and run the system,after opening the
L.S coupling. The running current may be 10% more.
3.After thorough checking of the conveyor,for correct lay out, blocked chute,seized pulleys etc,the conveyor may be started.
It must run.
Rgds,
Narayanan Nalinakshan. ■
Starting Problem Of The Motor.
Originally Posted by sganeshRegards,
Dear Sandipan,
Hope it is a cage motor. 650 amps indicate locked rotor-repeated trial will result in motor failure
The Problem may be Power Supply,Motor ,Gear box or the conveyor system.
I suggest the following checks,
1.This may be an LT motor (415 volts),please check the terminal voltages in all the three phase.If it is O.K,rotate the motor alone with hand.
If it is O.K,Start the motor alone,with out fluid coupling.It must run,with a nominal current of 10 to 15% of full load current in all the three phases, if not the motor
may be faulty.
2.Check the fluid coupling and gear box for freeness by hand rotation. If there is a built in hold back ensure it is working for correct direction.
If they are O.K,connect the motor, fluid coupling,gear box and run the system,after opening the
L.S coupling. The running current may be 10% more.
3.After thorough checking of the conveyor,for correct lay out, blocked chute,seized pulleys etc,the conveyor may be started.
It must run.
Rgds,
Narayanan Nalinakshan. ■
Re: Starting Problem Of A Belt Conveyor
Originally Posted by Gary BlenkhornHas the fluid level in the fluid coupling been set correctly?
Assuming that the motor is 3 phase have you checked for single phasing and secure motor lead connections?
Does the conveyor start to move prior to the trip out?
I also moved your thread to a more appropriate forum.
This is a new installation, Fluid level is ok, it is a 3Ph motor. Conveyor does not start, however, forwrard movement of belt is possible manually rotating the output side of fluid coupling by 2/3 persons which further shows that belt is free to move. Thanks....... ■
Re: Starting Problem Of A Belt Conveyor
Originally Posted by Gary BlenkhornHas the fluid level in the fluid coupling been set correctly?
Assuming that the motor is 3 phase have you checked for single phasing and secure motor lead connections?
Does the conveyor start to move prior to the trip out?
I also moved your thread to a more appropriate forum.
This is a new installation, Fluid level is ok, it is a 3Ph motor. Conveyor does not start, however, forwrard movement of belt is possible manually rotating the output side of fluid coupling by 2/3 persons which further shows that belt is free to move. Thanks....... ■
Re: Starting Problem Of A Belt Conveyor
Dear sandipandaw,
From your thread, we know that you have a starting problem at empty condition with a new belt conveyor.
All components seem to be able to be turned manually, indicating that there is no jamming at very low speed.
In general, your problem can be originated in three levels:
-Design:
Check the design calculations again. (If possible give the design free in this thread)
-Execution:
Check whether the assumed design parameters are consistent with the executed installation parameters. (f.i. the power supply voltage)
- Technical:
A technical problem has to be investigated step by step, as Gary, Roland, sganesh and Narayanan Nalinakshan already suggested.
A logical way to do the research is starting the motor with all components after the motor disconnected and measure and monitor the starting currents in all 3 phases and reached rpms. Also observe how the starting goes.
Then connect the first component after the e-motor and start again.
Then connect the next component and restart again.
When the problem reoccurs, then the last connected part is causing the problem.
For the forum members it is a bit difficult to have an idea of what is going wrong without the complete information and no opportunity to evaluate the design, the real execution and the test results.
An installation, which is reported to be able to be moved by hand and still not able to be started is almost impossible to evaluate at a distance, without you being the eyes and ears for us.
Hope to have your feedback soon.
Have a nice day
Teus ■
Teus
Re: Starting Problem Of A Belt Conveyor
Dear sandipandaw,
From your thread, we know that you have a starting problem at empty condition with a new belt conveyor.
All components seem to be able to be turned manually, indicating that there is no jamming at very low speed.
In general, your problem can be originated in three levels:
-Design:
Check the design calculations again. (If possible give the design free in this thread)
-Execution:
Check whether the assumed design parameters are consistent with the executed installation parameters. (f.i. the power supply voltage)
- Technical:
A technical problem has to be investigated step by step, as Gary, Roland, sganesh and Narayanan Nalinakshan already suggested.
A logical way to do the research is starting the motor with all components after the motor disconnected and measure and monitor the starting currents in all 3 phases and reached rpms. Also observe how the starting goes.
Then connect the first component after the e-motor and start again.
Then connect the next component and restart again.
When the problem reoccurs, then the last connected part is causing the problem.
For the forum members it is a bit difficult to have an idea of what is going wrong without the complete information and no opportunity to evaluate the design, the real execution and the test results.
An installation, which is reported to be able to be moved by hand and still not able to be started is almost impossible to evaluate at a distance, without you being the eyes and ears for us.
Hope to have your feedback soon.
Have a nice day
Teus ■
Teus
Starting Problem Of Conveyor.
Dear Sandeep,
Few more Check,
1. Check the electrical parameters of the motor like resistance of all phases,continuity etc.
2. How long is the cable from the motor starting panel. If it is too long,the voltage drop may be too much while starting the motor,
and the motor at low terminal voltage will not be able to pull up.If the voltage drop is too much,you may have to go for extra run of cable.
Rgds,
Narayanan Nalinakshan.
From your thread, we know that you have a starting problem at empty condition with a new belt conveyor.
All components seem to be able to be turned manually, indicating that there is no jamming at very low speed.
In general, your problem can be originated in three levels:
-Design:
Check the design calculations again. (If possible give the design free in this thread)
-Execution:
Check whether the assumed design parameters are consistent with the executed installation parameters. (f.i. the power supply voltage)
- Technical:
A technical problem has to be investigated step by step, as Gary, Roland, sganesh and Narayanan Nalinakshan already suggested.
A logical way to do the research is starting the motor with all components after the motor disconnected and measure and monitor the starting currents in all 3 phases and reached rpms. Also observe how the starting goes.
Then connect the first component after the e-motor and start again.
Then connect the next component and restart again.
When the problem reoccurs, then the last connected part is causing the problem.
For the forum members it is a bit difficult to have an idea of what is going wrong without the complete information and no opportunity to evaluate the design, the real execution and the test results.
An installation, which is reported to be able to be moved by hand and still not able to be started is almost impossible to evaluate at a distance, without you being the eyes and ears for us.
Hope to have your feedback soon.
Have a nice day
Teus[/QUOTE] ■
Starting Problem Of Conveyor.
Dear Sandeep,
Few more Check,
1. Check the electrical parameters of the motor like resistance of all phases,continuity etc.
2. How long is the cable from the motor starting panel. If it is too long,the voltage drop may be too much while starting the motor,
and the motor at low terminal voltage will not be able to pull up.If the voltage drop is too much,you may have to go for extra run of cable.
Rgds,
Narayanan Nalinakshan.
From your thread, we know that you have a starting problem at empty condition with a new belt conveyor.
All components seem to be able to be turned manually, indicating that there is no jamming at very low speed.
In general, your problem can be originated in three levels:
-Design:
Check the design calculations again. (If possible give the design free in this thread)
-Execution:
Check whether the assumed design parameters are consistent with the executed installation parameters. (f.i. the power supply voltage)
- Technical:
A technical problem has to be investigated step by step, as Gary, Roland, sganesh and Narayanan Nalinakshan already suggested.
A logical way to do the research is starting the motor with all components after the motor disconnected and measure and monitor the starting currents in all 3 phases and reached rpms. Also observe how the starting goes.
Then connect the first component after the e-motor and start again.
Then connect the next component and restart again.
When the problem reoccurs, then the last connected part is causing the problem.
For the forum members it is a bit difficult to have an idea of what is going wrong without the complete information and no opportunity to evaluate the design, the real execution and the test results.
An installation, which is reported to be able to be moved by hand and still not able to be started is almost impossible to evaluate at a distance, without you being the eyes and ears for us.
Hope to have your feedback soon.
Have a nice day
Teus[/QUOTE] ■
Re: Starting Problem Of A Belt Conveyor
Dear sandipandaw,
Another thought:
While starting, the motor is drawing high current in the range of 650amps and getting tripped.
Assuming a low voltage (400 V) squirrel cage motor of 90 kw, the full load current would be around 160 Amps.
The starting current at direct on line would be approx. 8* 160 = 1280 A
You are withdrawing 650 amps from the grid.
That means that the delivered torque during starting is approx. 650/1280 = 50% of the full load torque of the motor.
If you have chosen an e-motor of the wrong rotor class, with a very low saddle torque, you might be getting close to a point where the initial starting friction cannot be overcome by the reduced e-motor torque.
Check the drive curves.
Success
Teus ■
Teus
Re: Starting Problem Of A Belt Conveyor
Dear sandipandaw,
Another thought:
While starting, the motor is drawing high current in the range of 650amps and getting tripped.
Assuming a low voltage (400 V) squirrel cage motor of 90 kw, the full load current would be around 160 Amps.
The starting current at direct on line would be approx. 8* 160 = 1280 A
You are withdrawing 650 amps from the grid.
That means that the delivered torque during starting is approx. 650/1280 = 50% of the full load torque of the motor.
If you have chosen an e-motor of the wrong rotor class, with a very low saddle torque, you might be getting close to a point where the initial starting friction cannot be overcome by the reduced e-motor torque.
Check the drive curves.
Success
Teus ■
Teus
Drive Away
Originally Posted by sandipandawDear Ssandipan,
if low speed coupling is disconnected, the moveability of output side of fcplg is still not eveything. Did you turn the drive pulley after lifting the belt, but take care as said.
However #1: in support of Teus and others, have an in-depth look at the motor. There, pls. check the drive curves and if possible have them validated with your motor on suppliers indications, else get a replacement with correct & certified saddle torque.
However #2: You speak of being 650 Amp being high current, but see Teus' answer, it isn't! Check your e-supply / grid amperage.
Regards
R. ■
Drive Away
Originally Posted by sandipandawDear Ssandipan,
if low speed coupling is disconnected, the moveability of output side of fcplg is still not eveything. Did you turn the drive pulley after lifting the belt, but take care as said.
However #1: in support of Teus and others, have an in-depth look at the motor. There, pls. check the drive curves and if possible have them validated with your motor on suppliers indications, else get a replacement with correct & certified saddle torque.
However #2: You speak of being 650 Amp being high current, but see Teus' answer, it isn't! Check your e-supply / grid amperage.
Regards
R. ■
Re: Starting Problem Of A Belt Conveyor
Thanks to all. As advised, i'll check the T-S curve of motor and fluid coupling and super impose them to find out if the problem lies there. Meanwhile the calculation along with belt profile is attached for your ref.
Regards
Sandipan
Originally Posted by Teus TuinenburgAnother thought:
Assuming a low voltage (400 V) squirrel cage motor of 90 kw, the full load current would be around 160 Amps.
The starting current at direct on line would be approx. 8* 160 = 1280 A
You are withdrawing 650 amps from the grid.
That means that the delivered torque during starting is approx. 650/1280 = 50% of the full load torque of the motor.
If you have chosen an e-motor of the wrong rotor class, with a very low saddle torque, you might be getting close to a point where the initial starting friction cannot be overcome by the reduced e-motor torque.
Check the drive curves.
Success
Teus
■
Re: Starting Problem Of A Belt Conveyor
Thanks to all. As advised, i'll check the T-S curve of motor and fluid coupling and super impose them to find out if the problem lies there. Meanwhile the calculation along with belt profile is attached for your ref.
Regards
Sandipan
Originally Posted by Teus TuinenburgAnother thought:
Assuming a low voltage (400 V) squirrel cage motor of 90 kw, the full load current would be around 160 Amps.
The starting current at direct on line would be approx. 8* 160 = 1280 A
You are withdrawing 650 amps from the grid.
That means that the delivered torque during starting is approx. 650/1280 = 50% of the full load torque of the motor.
If you have chosen an e-motor of the wrong rotor class, with a very low saddle torque, you might be getting close to a point where the initial starting friction cannot be overcome by the reduced e-motor torque.
Check the drive curves.
Success
Teus
■
Going On
Dear Sandipan Daw,
without recalculating the design: Judging from belt tension difference at drive pulley, the choice of motor size seems rather sound. But then: There's no inertia values given in those tables. Then, for commissioning & everything is new and with that amount of pulleys & Dm 152(!) rollers --> new bearings & a new = stiff belt: There will be a breakaway torque requirement rather larger than that calculated for steady operational running or starting.
Pls. specify: Inrush amperage for start of motor must be ~ Teus' value. Saddle torque amperage will approximately be in the region you mentioned. Grid must deliver both, and amp-out relay switch handle esp. the second for the required length of time.
Which leads me to the fl. cplg. Pls. specify: When starting the setup, did you observe a tensioning up of the belt in the upper strand, as the pulley moved just as far as pulling out of belt sag allowed? And, didn't the fluid cplg turn HOT from getting all that power all to itself? The fl cplg is not mentioned in the table, this is irritating. However if designed after motor size it should be a robust size. Hopefully with a melting plug and a duly designed receptacle underneath & protection cover all around.
After all due checking for jamming, blocked pulley bearings and so on, you'll have to discuss with your designers, conclude & fix with them a warranty - keeping startup solution reconsidering pretension, fill of cplg, startup sequence, ... --> others... in order to overcome the initial breakaway resistance.
I do sincerely not hope the system was changed after design stage.
Again:
Pls. be most careful when disconnecting the drive unit from drive pulley, as the backstop is integrated into gearbox. The belt must be duly untensioned and clamped.
Pls. be careful with builtup of tension against the holdback which might fail and the freed forces might over-accelerate the fl-cplg until explosion.
Regards
R. ■
Going On
Dear Sandipan Daw,
without recalculating the design: Judging from belt tension difference at drive pulley, the choice of motor size seems rather sound. But then: There's no inertia values given in those tables. Then, for commissioning & everything is new and with that amount of pulleys & Dm 152(!) rollers --> new bearings & a new = stiff belt: There will be a breakaway torque requirement rather larger than that calculated for steady operational running or starting.
Pls. specify: Inrush amperage for start of motor must be ~ Teus' value. Saddle torque amperage will approximately be in the region you mentioned. Grid must deliver both, and amp-out relay switch handle esp. the second for the required length of time.
Which leads me to the fl. cplg. Pls. specify: When starting the setup, did you observe a tensioning up of the belt in the upper strand, as the pulley moved just as far as pulling out of belt sag allowed? And, didn't the fluid cplg turn HOT from getting all that power all to itself? The fl cplg is not mentioned in the table, this is irritating. However if designed after motor size it should be a robust size. Hopefully with a melting plug and a duly designed receptacle underneath & protection cover all around.
After all due checking for jamming, blocked pulley bearings and so on, you'll have to discuss with your designers, conclude & fix with them a warranty - keeping startup solution reconsidering pretension, fill of cplg, startup sequence, ... --> others... in order to overcome the initial breakaway resistance.
I do sincerely not hope the system was changed after design stage.
Again:
Pls. be most careful when disconnecting the drive unit from drive pulley, as the backstop is integrated into gearbox. The belt must be duly untensioned and clamped.
Pls. be careful with builtup of tension against the holdback which might fail and the freed forces might over-accelerate the fl-cplg until explosion.
Regards
R. ■
Down Under?
Dear Mr. Sandipan Daw,
i certainly do not hope the monsoon season interrupted all communications, and also that you could advance the issue you required support. However, how about some feedback? It is good to feed those who answer back, don't you agree?
Regards
R. ■
Down Under?
Dear Mr. Sandipan Daw,
i certainly do not hope the monsoon season interrupted all communications, and also that you could advance the issue you required support. However, how about some feedback? It is good to feed those who answer back, don't you agree?
Regards
R. ■
Re: Starting Problem Of A Belt Conveyor
Hello,
Conveyor can fail to start by various reasons. Some are as below:
i) Belt tension not adequate to transmit starting torque, resulting in belt slip, and zero speed switch trips the motor. If it has gravity take-up then counterweight not adequate. If winch take-up, winch take-up setting is inadequate.
ii) You have mentioned fixed tripper. If it has concave radius, belt will lift up during starting if concave radius is not adequate. The belt lift-up may reduce the tension at head pulley, resulting in belt slip and motor gets tripped as above.
iii) Belt sway switch tripping the motor.
iv) Tripping setting too sensitive.
v) Inadequate / faulty motor.
vi) Fluid coupling under filling or over filling. Under filling will make starting time too long to be allowed by time sensor. Over filling results into too harsh starting and overload sensor action.
vii) Look at the take-up behaviour, concave zone behaviour, whether gear box actual ratio is as per its name plate, wrong / malfunction of electrical sensors and safety features, etc.
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 ■
Re: Starting Problem Of A Belt Conveyor
Hello,
Conveyor can fail to start by various reasons. Some are as below:
i) Belt tension not adequate to transmit starting torque, resulting in belt slip, and zero speed switch trips the motor. If it has gravity take-up then counterweight not adequate. If winch take-up, winch take-up setting is inadequate.
ii) You have mentioned fixed tripper. If it has concave radius, belt will lift up during starting if concave radius is not adequate. The belt lift-up may reduce the tension at head pulley, resulting in belt slip and motor gets tripped as above.
iii) Belt sway switch tripping the motor.
iv) Tripping setting too sensitive.
v) Inadequate / faulty motor.
vi) Fluid coupling under filling or over filling. Under filling will make starting time too long to be allowed by time sensor. Over filling results into too harsh starting and overload sensor action.
vii) Look at the take-up behaviour, concave zone behaviour, whether gear box actual ratio is as per its name plate, wrong / malfunction of electrical sensors and safety features, etc.
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 ■
Starting Problem of a Belt Conveyor
We have a belt conveyor length is approx 420M & lift 20M with fixed tripper of 200TPH carrying sinter. Consumed power calculated is 65KW,motor selected is 90KW with fluid coupling at high speed side. To our surprise, the belt at empty condition is not starting. While starting, the motor is drawing high current in the range of 650amps and getting tripped. All alignment and jamming has been checked for all mechanical components. Further,the motor is rotating with fluid coupling and gearbox input/output shafts when the low speed coupling is decoupled from pulley. Can anybody give any possible reason and the solution. ■