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Metal Detector Problem

05/24/2016 7:10 AM

Sir,

I am working in the food company. i have got the metal detector installed on the filling lines.The problem is that there are two setting in that one is senstivity & the second is product angle. but the problem is that instrument is sensing the false signal always. due to this its not working properly. its happening in all the four machines i have got. my question is that can there is chances of harmonics present in the power supply. can any one help.

Thanks & Regards

Ashutosh Goyal

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#1

Re: Metal Detector problem

05/24/2016 7:14 AM

What did the manufacturer say when you called them? What does the manual say about it?

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#2

Re: Metal Detector problem

05/24/2016 8:00 AM

<...Sir...> presupposes that all readers of this forum are male; this is not the case.

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#3

Re: Metal Detector problem

05/24/2016 8:55 AM

Just a thought, are the metal detectors vibrating when the filling lines are operating? If so, find a way to stabilize them.

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#4

Re: Metal Detector Problem

05/24/2016 9:52 AM

It is possible the root of your problem lies in your power supplies but it is far, far more likely the problem lies elsewhere. I say this because a power supply rarely fails in the intermittent fashion you imply. Usually when a power supply fails it continues to fail.

I chose the term "imply" because it is not clear how all four detectors are used when they generate each false alarm. Are all four triggering at the same time while testing the same product or different products? You give us no information on what if anything correlates with these false trips. To me this lack of correlation information implies that you do not see any correlation with these trips. These false alarms are random events. Random events imply a noise or interference related problem. Solving a noise related problem is difficult when one has the unit in front of them with all schematics and test instruments available. It is impossible to solve on an open forum. Particularly when one has to assume information.

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#9
In reply to #4

Re: Metal Detector Problem

05/24/2016 11:53 PM

THe false signal is totally random. even there is no product in the conveyer the false alarm is still coming. & automatically is comes to down level in 5 min or 5 hrs . not depending of anything. from outside we have tries all things like noise vibration earthing ,neutral earthing voltage, glanding of shielded cables but all in vain no solution for the problem.

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#11
In reply to #9

Re: Metal Detector Problem

05/25/2016 6:49 AM

Does the false signal come when the conveyor is turned off? Have you tested that to see? This simple test would narrow the possible causes significantly.

Perhaps you should stop just doing things to try to make it work and start doing things that help you figure out the cause of the problem. otherwise it will continue to seem like an impossible problem to fix.

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#14
In reply to #9

Re: Metal Detector Problem

05/25/2016 9:17 AM

Solar Eagle may have your answer in his post with all the good answer marks. You need to put gold screen all surrounding the detector and see if that helps, then try just shielding everything around the detector, but allow its line of sight to the product conveyor. Or maybe your detector is so sensitive, it is picking up very minute fragments of metal than you cannot see.

If the conveyor belt moving when the false signals show up? Suppose everything is static in the building, does it still happen? Is there a Faraday shield up around the detector, so that side electromagnetic signal is not picked up? Solar flares?

Maybe you have invented a ghost detector, maybe we can all start "believing" in contact with the "other side". This is certainly a mysterious problem. Have you tried taking away the offending detector and installing other detector, or other type of detector?

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#5

Re: Metal Detector Problem

05/24/2016 11:09 AM
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#8
In reply to #5

Re: Metal Detector Problem

05/24/2016 3:52 PM

Hmmm....let me see. Salt, meat, including ham. I see a metal canned ham being detected in your future.

Did these detectors work previously, did something change (as in a repair) that put metal parts on the line? What is the frequency (1/time) of the alarms? Does it have to do with conveyor belt trip frequency? Maybe they put a failed belt back together using steel clips instead of the original.

Seriously though, perhaps you should remove these metal detectors (one at a time if you must), and run your own calibrations, sensitivities, and power supply checks. They make temperature loggers you can use to understand what is passing by on the line. They also make voltage loggers for the power supply stability check (although this is not your problem, AFAICT).

I believe you have electromagnetic resonance with some food products, or something connected (like packaging, etc.) with this food. What if you move the metal detectors closer to the food passing by and decrease the sensitivity? Same false alarms? Now try moving them further back with increased sensitivity...result?

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#6

Re: Metal Detector Problem

05/24/2016 1:02 PM

my question is that can there is chances of harmonics present in the power supply.

possible....

Don't know what the design is...

Do you have it isolated from any vibration from the conveyor?

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#7

Re: Metal Detector Problem

05/24/2016 3:48 PM

It's more likely the devices are not fit for the application or have been installed incorrectly (perhaps picking up the metal parts in the conveyor).

Go back and have a careful look at the manual and any online application notes for the product, it could be something quite simple or it could be that the detector is not correct for your application or product and you need something else.

If the devices are sensitive to supply fluctuations or harmonics this should be indicated in the manual.

If still in doubt try the manufacturer.

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#10

Re: Metal Detector Problem

05/25/2016 5:12 AM

Does the detector always work when you deliberately put metal in the product? Can you turn down the sensitivity?

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#12
In reply to #10

Re: Metal Detector Problem

05/25/2016 7:48 AM

No, signal strength is always random in all the four machines even if i am not passing any product & even the conveyor is on idle position the metal detector catch the false signal at that time aswell .

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#13

Re: Metal Detector Problem

05/25/2016 8:59 AM

First I would agree with previous posters that you should contact either your sales representative or seller to discuss this issue (assuming these are new units). If they are being relocated from elsewhere, your local representative should still provide technical information in order to maintain/start a good relationship with your company and possibly rack up future sales.

With that said, did you provide a dedicated power circuit to the units or tap into an existing line? We found by experience that nuisance trips are quite possible and seemingly random in nature (with and without product present) if the power is from a circuit with other loads. These other loads can cause enough of a spike in the circuit when turning on and off that the detector fault trips for a second or two. Isolating to a dedicated power supply corrected this issue (and yes, the vendor provided troubleshooting assistance although this requirement was clearly stated in the instructions).

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#15
In reply to #13

Re: Metal Detector Problem

05/25/2016 9:40 AM

I agree, and add that user may have to introduce further electromagnetic shielding, since I suspect the working principle of the detector is inductive.

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#16
In reply to #15

Re: Metal Detector Problem

05/25/2016 11:07 AM

Inductance is only one part of how a metal detector works. Adding magnetic shielding may cause a constant detection of metal or complete insensitivity to metal in the food.

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#17
In reply to #16

Re: Metal Detector Problem

05/25/2016 11:17 AM

Isn't there some directionality to the induction loops? I understood these devices to work by changes in the magnetic susceptibility in the area subtended by the most intense part of the field radiated.

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#18

Re: Metal Detector Problem

05/25/2016 3:41 PM

What exactly is the metal detector you are using (brand, model and part number)?

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#19
In reply to #18

Re: Metal Detector Problem

05/25/2016 3:43 PM

Details!? You must be joking.

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#20
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Re: Metal Detector Problem

05/25/2016 4:20 PM

Whole thing sounds bad enough to be a complete abortion in the waste container outside.

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#21
In reply to #18

Re: Metal Detector Problem

05/26/2016 4:00 AM

Make- S+ S Model-Rapid Compact 100 type-Unicon. Can i believe now that the problem lies on my power supply means harmonics distortion. if so then what is the remedy for this.

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#22
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Re: Metal Detector Problem

05/26/2016 4:42 AM

Please, contact the manufacturer.

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#23
In reply to #21

Re: Metal Detector Problem

05/26/2016 4:54 AM

Dedicated supply with mains filter as kbp1958 said at post 13.

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#24
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Re: Metal Detector Problem

05/26/2016 8:42 AM

Contact the OEM, Original Equipment Manufacturer! You have a worthless power supply on a worthless machine. If they will not remedy the problem, throw the power supply in the garbage, and put in a large car battery to power this worthless metal detector, and a large battery charger. Charge the battery at night, if the food line is off at night.

I can send you a consult bill if you like, otherwise learn to dial a telephone.

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#25

Re: Metal Detector Problem

06/09/2016 7:48 AM

It sounds to me as though ALL the detectors have been installed in places totally unsuitable for them (assuming no other problems like bad power supplies or the like.....)

A picture would help maybe?

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