# Magnetic reed switch alternative



## gpop (May 14, 2018)

Sounds more like a interlock switch than a basic magnetic reed switches. A different brand might be easy to source but the word interlock and cheap isn't going to happen.


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## CoolWill (Jan 5, 2019)

Could you use a Hall effect sensor to power a relay with NO and NC contacts?


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## macmikeman (Jan 23, 2007)

Have you looked in the ADI CATALOG? I've bought door monitoring switches in past years that were form C. Long time ago though, so don't ask me the brand. 

They weren't cheapy plastic kine either, these were metal housings and no sticky tape crapola, you had to mount them with screws.


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## splatz (May 23, 2015)

I feel like I'm missing something, I found form C / spdt magnetic proximity sensors all over the place with a web search - at HSI Sensing, Steven Engineering, Standex Electronics and others. Not just alarm system quality stuff, a lot of these look suitable for or specifically made for industrial applications.


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## paulengr (Oct 8, 2017)

IFM Efrcgg Th or. This is kind of their thing. Used a lot on hydraulic cylinders. Lasts decades.


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## paulengr (Oct 8, 2017)

IFM Efector. Stupid Chinese Foxconn phone with Apple Spyware err I mean OS, comrades.


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## Jlarson (Jun 28, 2009)

IFM and Balluff hall effect sensors are the main ones I use.


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## Mbit (Feb 28, 2020)

splatz said:


> I feel like I'm missing something, I found form C / spdt magnetic proximity sensors all over the place with a web search - at HSI Sensing, Steven Engineering, Standex Electronics and others. Not just alarm system quality stuff, a lot of these look suitable for or specifically made for industrial applications.



I just read this and now I'm thinking I've been confusing myself. Form C should be all I need. But I'm thinking the reason they have 2 completely separate circuits actually is the alarm comes from a completely separate source. The PLC is the other voltage source.



I need to look at this again. Motor spun off it's foundation last night so I'm stringing some temp SO cord.


Thanks for suggestions and brain power gents


Will update after some investigation


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## Mbit (Feb 28, 2020)

After checking drawings they are 2 different systems. So I need either two SPDT or a N.C. and an N.O. So that can keep them separate.


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## Mbit (Feb 28, 2020)

Jlarson said:


> IFM and Balluff hall effect sensors are the main ones I use.





paulengr said:


> IFM Efector. Stupid Chinese Foxconn phone with Apple Spyware err I mean OS, comrades.
> 
> 
> Sent from my iPhone using Tapatalk



Checked those catalogs. Basically you can get N.C., N.O. or SPDT but they don't offer 2 separate sets of contacts from one magnetic proximity switch.



We have a bunch of Baluff N.O. PNP for our hydraulic gate valves and they work great


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## splatz (May 23, 2015)

I still might not follow, but. So you want four wires to go to four inputs, it wouldn't work to just splice the common to both inputs? I assume the reason for that is, you want the two isolated? 

If so, use the three wires from the form C / SPDT sensor, and share the common on the coils of two interposing relays for isolation. The contacts of the interposing relays will be isolated.


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## Mbit (Feb 28, 2020)

splatz said:


> I still might not follow, but. So you want four wires to go to four inputs, it wouldn't work to just splice the common to both inputs? I assume the reason for that is, you want the two isolated?
> 
> If so, use the three wires from the form C / SPDT sensor, and share the common on the coils of two interposing relays for isolation. The contacts of the interposing relays will be isolated.



Currently the mag reed switches are acting as isolated dry contacts. 2 SPDT encapsulated in each switch but we're only using them as 1 N.C. and 1 N.O.


Yes I don't want to mix the voltages from the 2 systems, one is a PLC strictly for our process the other comes from a separate console.



2 N.O. contacts in series(1 from each reed switch, 1 reed switch per ram, 2 rams per door) close when both the cylinders are retracted and send a high to a DI on the "process" PLC. 



2 N.C. contacts in parallel (1 from each reed switch, 1 reed switch per ram, 2 rams per door) open when both the cylinders are retracted and extinguish an indicator light on an operator console.


the "relaxed" state of the rams is extended.


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## splatz (May 23, 2015)

OK so the two SPDT switches in the sensor are for redundancy, AND for the safe condition, OR for the caution condition. 

The NO contacts of each SPDT energizes the coil of a DPDT relay. 

Use pole one on each relay for the series arrangement for the process PLC; use pole two on each relay for the parallel arrangement for the light on the operator console. 



Mbit said:


> Currently the mag reed switches are acting as isolated dry contacts. 2 SPDT encapsulated in each switch but we're only using them as 1 N.C. and 1 N.O.
> 
> 
> Yes I don't want to mix the voltages from the 2 systems, one is a PLC strictly for our process the other comes from a separate console.
> ...


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## Mbit (Feb 28, 2020)

splatz said:


> OK so the two SPDT switches in the sensor are for redundancy, AND for the safe condition, OR for the caution condition.
> 
> The NO contacts of each SPDT energizes the coil of a DPDT relay.
> 
> Use pole one on each relay for the series arrangement for the process PLC; use pole two on each relay for the parallel arrangement for the light on the operator console.



O,k cool. I would not have thought of that thank you


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## just the cowboy (Sep 4, 2013)

Check to see what is required by law. You are now in a safety circuit. 
If you do any rewiring you may have to go to safety relays, they use two sets of contacts and check for both closing at the same time. If you don't make it meet safety requirements you may be liable if anyone gets hurt.

Just food for thought.

Cowboy


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## Mbit (Feb 28, 2020)

Ok guys I moved on to another site so I guess I won't be working on this anymore. But I did learn something.


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## paulengr (Oct 8, 2017)

If you run into this again the obvious solution is to run the sensor to a relay and at that point the standard ones have 1-4 form C contacts.


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## just the cowboy (Sep 4, 2013)

@Mbit. Thank for for closing thread. What did you end up doing?


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## Mbit (Feb 28, 2020)

just the cowboy said:


> @Mbit. Thank for for closing thread. What did you end up doing?


Moved to a new job and never ended up implementing any of the solutions discussed on here. Just spent all day screwing around with an unmarked wye delta start circuit that was miswired badly. Luckily a trick I learned on here came in handy. Thanks gents.

http://www.electriciantalk.com/attachments/f28/12464d1332156508-motor-6-lead-identification-6leadtst.pdf


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## Mbit (Feb 28, 2020)

paulengr said:


> If you run into this again the obvious solution is to run the sensor to a relay and at that point the standard ones have 1-4 form C contacts.


Thanks Paul, but be careful because now I might be tagging you on all of my request for help posts on here:biggrin:


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## paulengr (Oct 8, 2017)

Mbit said:


> Thanks Paul, but be careful because now I might be tagging you on all of my request for help posts on here:biggrin:


I love IFM Efector but I think I know why they are NO only. Every version I've ever used uses electronic (TRIAC or transistor) outputs so it has to turn on to conduct where NC has to turn off to conduct. There are some devices that work this way but I haven't seen them used for solid state outputs.


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