hello

is it possible with proximity sensor to adjust delay to switching?

regard

No.

Proximity sensor switch is only ON-OFF type. User need to use timer to proxy out put for delay application.

hamed12580

hello

is it possible with proximity sensor to adjust delay to switching?

regard

 Hello hamed,

Accessories Pulse Extender

Hello Hamed,

hamed12580

hello

is it possible with proximity sensor to adjust delay to switching?

regard

My interest in this question is in "why" you asked this question. If we knew that, the answers may look a bit different.

Some random tips -
Inductive sensors are not created equal. The sensor differ between various manufacturers. Some sensors are manufactured using an older technique. For this case the type material being detected, supplied voltage and distance of sensor to the target is critical.

Detecting Aluminium may give a variant result with the sensor distance at the distance specified for Steel.

The counter balance: Sensors built from new techniques, can interfere with each other. Some send out radio frequencies that influences another sensor that is mounted close by.

Knowing the specification of the sensor and knowing how it behaves in the field, is important where repeatable and quick acting results are needed.

BR

hello

I asked this question because i saw an AC PROXIMITY SENSOR which is used in traditional power and command circuit ( i mean without plc) to detect rotation of a conveyor shaft ,this sensor acts as a NC switch in command circuit,i mean it is connected with other element like stop button and 95-96 thermal relay in series to contactors coil ,when the shaft isnt rotating it will stop the previous motor,i wondered how this sensor doesnt make contactor to on-off when shaft rotating,i thought maybe it has delay in switching

regards

Hello.

hamed12580

hello

I asked this question because i saw an AC PROXIMITY SENSOR which is used in traditional power and command circuit ( i mean without plc) to detect rotation of a conveyor shaft ,this sensor acts as a NC switch in command circuit,i mean it is connected with other element like stop button and 95-96 thermal relay in series to contactors coil ,when the shaft isnt rotating it will stop the previous motor,i wondered how this sensor doesnt make contactor to on-off when shaft rotating,i thought maybe it has delay in switching

regards

It sounds like a clever design you are describing. Do you have a  electrical drawing of this & are you able to share it?

There are contactors that has bolt-on timers. But I am sure you would have seen it, if that was the case. There are sensors in the field that has built-in timers - but again it would be clear to you if there was such a thing.

Another trick is to utilize the timer from a VSD (variable speed drive). That is more sneaky as it is not so visible for the casual observer. But from your description it does not sound as if a VSD was used.

So my words are like that of the politicians.. many sentences but no answers.

hello

it hasnt any electrical plan but i will note the sensor and contactor manufacture and serial and download datasheet for more information

thx

It is a quite clever way to monitor shaft rotation in hardware.  You select a terrible AC prox, meaning it has horrible hysteresis time or some trait you wish to leverage.

You then perhaps bolt on an oddly shaped chunk of metal easily detectable by the prox, but only when it is within a certain distance of the oddly shaped chunk of metal and only if the shaft is rotating above minimum required speed.  The motor needs to run a certain speed or it stalls for example.  This is a very old-school design, but very simple and elegant and clever. 

First time I saw it, I had to learn how it worked.  You adjust the prox too close, it hits the weirdly shaped rotating object.  Too far away and it toggles the output signal or never comes on.

In the sweet spot, which for the terrible AC prox is rather generous as prox's go, and first time it sees the edge of that rotating "cam" lobe, it turns on.  Hysteresis time being so bad, it stays on for say 300msec.  In that time, if the shaft cam lobe rotates past it again, it stays on constantly.  The cam lobe itself is not a large enough target to activate the prox, but if it is rotating through the ac field created by the prox fast enough, it induces a large signal and fires the prox state change.

Once changed, it stays changed until the shaft stops or the cam lobe slows down so the prox sees it only maybe 2 times a second.  Then it goes off.

Very good interlocking device provided the cam lobe and crappy ac inductive prox are matched and properly adjusted.  Sadly, that cam lobe set screw will come loose at some point and because it is often in a difficult to reach place, and anyone who remembers how to adjust these things has long since retired, people instead say, hey, let's install a VFD to control the conveyor motor, use a digital output to drive an interlock relay for the motor not running, and be done with it.

Works fine, and much safer.  Or, they can install a contactor and monitor the contactor state along with a much more complicated way of monitoring physical conveyor motion than that cam / prox deal.  That cam shaped thing had a patent for when it was invented way back in the early days of conveyor usage.  The lobe shape is what made it all work from what I was told (by people long since retired). Could all be a bunch of lies for all I know.  I was young and it sounded right, and when I tried to adjust them on my own, I saw how it worked.

#dP

Hello.

hamed12580

hello

I asked this question because i saw an AC PROXIMITY SENSOR which is used in traditional power and command circuit ( i mean without plc) to detect rotation of a conveyor shaft ,this sensor acts as a NC switch in command circuit,i mean it is connected with other element like stop button and 95-96 thermal relay in series to contactors coil ,when the shaft isnt rotating it will stop the previous motor,i wondered how this sensor doesnt make contactor to on-off when shaft rotating,i thought maybe it has delay in switching

regards

It sounds like a clever design you are describing. Do you have a  electrical drawing of this & are you able to share it?

There are contactors that has bolt-on timers. But I am sure you would have seen it, if that was the case. There are sensors in the field that has built-in timers - but again it would be clear to you if there was such a thing.

Another trick is to utilize the timer from a VSD (variable speed drive). That is more sneaky as it is not so visible for the casual observer. But from your description it does not sound as if a VSD was used.

So my words are like that of the politicians.. many sentences but no answers.