Re: Location Of Speed Sensor
There is no advantage to having it on one pulley vs another. We put them on the pulley closest to the PLC inputs for the shortest wire run. In our case it is typically on the snub closest to the drive or on the first bend of the gravity take-up.
On short conveyors with only 2 pulleys it is of course on the tail pulley. ■
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: Location Of Speed Sensor
Originally posted by Gary Blenkhorn
We put them on the pulley closest to the PLC inputs for the shortest wire run.
Sounds sensible, particularly on long machines. ■
Re: Location Of Speed Sensor
Dear Mr. Ganesh,
The zero speed switch is meant to stop the drive motor in case of any belt snap. In case of non functioning of ZSS, the head pulley will keep on rotating and loose belt will get folded and lead to any mishap.
As per me, the first pulley ot sense the looseness of the belt will be the Snub pulley at Drive end. Hence, I would prefer it at Drive Snub Pulley, from the reliability point of view.
Others may have different opinions on this matter, particularly since it is a dirty place.
In longer conveyor i.e. > 1Km or so, why can't we have ZSS at 2 or 3 non drive pulleys?
Regards
P. Rekhawar ■
Speed Sensor Or Zero Speed Switch
Dear Mr.Gary & Mr.Designer,
The wire laying and wire cost will be one time investment.
This cost may be much less compared to consequential loss if any thing happens if the speed sensor is not fixed at the ideal place.
Dear Mr.Rekhawar,
Agreed. But Zero speed switch will also stop the belt if the belt slips or drive pulley struggles to rotate. Snapping and stopping the motor is much at later and unwanted stage.
To keep my question simpler, let us assume that the imagined conveyor is 300 metres long from Head pulley to tail pulley (and having single drive fixed with head pulley as mentioned at the starting of the thread.) ■
Re: Location Of Speed Sensor
I think the Tail bend pulley is the ideal place.
I posted this question to know the opinions of experts. ■
Re: Location Of Speed Sensor
Dear Experts,
What are the advantages of a speed sensor, particularly if the conveyor has gravity take up?
Regards, ■
Re: Location Of Speed Sensor
A speed sensor can be used to monitor slippage in the system or can also be used as a zero speed switch.
We don't use a speed sensors per say. We have a proxy switch pick up a rotating target on a non drive pulley that is sensed for 50% of the rotation. This signal is an input to the PLC so that the PLC knows what "normal' is as far as revolution per minute based on counting pulses per minute. Pulse on + pulse off = 1 revolution. We then set a threshold limit that shuts down the conveyor when that threshold is breached. We also use this method as a zero speed shutdown. ■
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: Location Of Speed Sensor
Surely that is a speed sensor, it senses the speed using a digital principle ■
Re: Location Of Speed Sensor
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Yes you are correct designer. But it would not be marketed as a "speed sensor".
There are speed sensors that are marketed just for that purpose only.
As in the Seimens Sitrans WS100 pictured here.
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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: Location Of Speed Sensor
G'day,
I would put it on any non-drive pulley as it will tell you if the belt is not running. If it is fitted to the drive pulley, then it will only trigger if the drive coupling has failed.
The drive pulley will also fail to indicate a slipping belt. ■
Re: Location Of Speed Sensor
Looks suspiciously like a "Whirligig" to me
http://www.go4b.co.uk/uk/documents/whirligigUK.pdf ■
Belt Slip Detector
Reading the comments so far, the speed sensor being referred to appears to be a belt slip detector. Most of the conveyors I have had anything to work on, have been one on the driven pulley/s in the form of a speed encoder or proximity & multi tag target ring set to set the belt speed and acceleration and de-accellaration rate of change during starting, running & stopping. The encoder or proximity sensor has a further corresponding sensor/s to detect speed differentials away from the main drive pulley/s, and is usually situated at the tail pulley. There are other places where other sensors can be located so the digital (or analog) data can be logged to achieve a stability throughout the entire length of the conveyor. This is the reason that most PLC programs run with a minimum of 11 rungs in the PLC program and on particularly long belt systems, 13 or 14 rungs may be required.
Hope this helps. ■
Re: Location Of Speed Sensor
We don't use a speed sensors per say. We have a proxy switch pick up a rotating target on a non drive pulley that is sensed for 50% of the rotation. This signal is an input to the PLC so that the PLC knows what "normal' is as far as revolution per minute based on counting pulses per minute. Pulse on + pulse off = 1 revolution. We then set a threshold limit that shuts down the conveyor when that threshold is breached. We also use this method as a zero speed shutdown.
Thank you all.
Request to go through the first post on this thread. To detect the slippage in the system, what should be the best pulley ? Of course we cannot fix it in drive and take up pulley. Among the remaining other pulleys, I thought tail bend pulley is the best option.
Regards, ■
Re: Location Of Speed Sensor
Request to go through the first post on this thread. To detect the slippage in the system, what should be the best pulley ? Of course we cannot fix it in drive and take up pulley. Among the remaining other pulleys, I thought tail bend pulley is the best option.
Regards,
To detect slip, the best pulley is the tail pulley. Of course, if you are using a shaft mounted speed sensor, you will have to make sure that the tail pulley has a live shaft. ■
Re: Location Of Speed Sensor
We always put them in the tail pulley. But there is no difference choosing other pulley, but, as a standard, we always try tu use the same place. ■
Belt Speed Sensor.
We don't use a speed sensors per say. We have a proxy switch pick up a rotating target on a non drive pulley that is sensed for 50% of the rotation. This signal is an input to the PLC so that the PLC knows what "normal' is as far as revolution per minute based on counting pulses per minute. Pulse on + pulse off = 1 revolution. We then set a threshold limit that shuts down the conveyor when that threshold is breached. We also use this method as a zero speed shutdown.
Normally A proxy switch, which picks up signal from the rotating target on the non drive pulley is ussed as ZSS,which switch of the motor if it does not attain the rated speed in predetermined time(this time depends on the mass to be accelarated,5to 8 secs),while starting.The switch also switch off the motor when the speed drops due to any reason like chute jamming,belt snapping,or belt slip on the drive pulley on account of poor lagging, rain etc.For all these purpose the ideal position of ZSS is on the snub pulley immediately after the drive pulley.In case of more than one drive pulley the ZSS should be fitted on all drive snubs.
Rgds,
NarayananNalinakshan ■
Re: Location Of Speed Sensor
You need a full angle of wrap of at least 180 degrees to ensure the speed sensor records accurately therefore if it is not the take up it needs to be the tail pulley. If it is the tail pulley you need to make sure that there is sufficient take up tension at all times that the sensor does not detect slip for reasons of lack of take up tension
Cheers
Colin Benjamin
Gulf Conveyor Systems Pty Ltd
Conveyorsystemstechnology.com ■
Location of speed sensor
Dear all,
Imagine a conveyor with vertical take up with following pulleys.
Drive pulley - 1 ( This will be head pulley is also in my case).
Drive snub pulley - 1
Head bend pulley - 1
Take up pulley - 1
Tail bend pulley - 1
Tail pulley - 1
Where do you suggest to fix the speed sensor & why ?
( of course not in drive pulley and take up pulleys)
Kindly post your opinion. ■