Go Down

Topic: High curent high voltage checking from microcontroler (Read 345 times) previous topic - next topic

caslor

Jul 21, 2019, 08:39 pm Last Edit: Jul 22, 2019, 09:11 am by caslor Reason: make my attached picture to apear to my post
Hi

i want to build a project that the microcontroller will check the continuity of some  contacts

lets say that we have 4 doors that have  contacts to check if they are all closed (not independently)

because of the long distance between doors we have to use an   Ac 110v  for contacts continuity.

One thought is to use a AC 110v  Relay  and use one NO contact to pass the signal to my Microcontroller
(see schematic in picture)

Are any other methods , electronic parts  that can be used instead of a relay that can do the same thing ?





Thanks in advance

PS : most of the times i have problem to embed pictures from my google drive. ''insert image''  seems cant embed url link from google drive.. is any special code to add to my url links in order to appeared right in my posts ?  

ReverseEMF

#1
Jul 21, 2019, 08:57 pm Last Edit: Jul 21, 2019, 08:58 pm by ReverseEMF
PS : most of the times i have problem to embed pictures from my google drive. ''insert image''  seems cant embed url link from google drive.. is any special code to add to my url links in order to appeared right in my posts ?  
You're half way there: How To Embed Image In Post
"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

raschemmel

#2
Jul 21, 2019, 09:02 pm Last Edit: Jul 21, 2019, 09:16 pm by raschemmel
Is the distance too great to use 24V for the continuity ?


It looks like you have three copies of the same schematic (2 links and 1 attachment)

Not sure what you question is.
There are many ways to do this.

I don't see any connection between D4 and relay pin-12 so I'm not sure how that's supposed to work.
You should the relay deenergized you the common is not connecting to relay pin-14.
If you relay is energized then relay pin 12 is connected to GND but there is nothing connected to 12 so I don't see how that would help. Relay pin-14 looks like the N.C. contact but is not shown connected to the common when the relay is deenergized so it can't be a N.C. contact. Your schematic doesn't make sense
as shown.
Either the relay is energized and pin-14 is open or the relay is de-energized and 14 is connected to the common but neither is the case with your schematic.
So what's up ?
What is the total distance of the loop ?
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

ReverseEMF

#3
Jul 21, 2019, 09:41 pm Last Edit: Jul 21, 2019, 09:42 pm by ReverseEMF
Are you sure you need 110VAC for that?  I would do something more like 24V or 48V DC, and an Opto-isolator.


Like this:


"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

raschemmel

Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

raschemmel

I think he didn't have a schematic symbol for and closed SPST switch.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

caslor

#6
Jul 22, 2019, 09:23 am Last Edit: Jul 22, 2019, 09:37 am by caslor Reason: adding picture to my post
Thanks all for the interesting :)
(i make the change so the picture will appear to my original post)


in the relay   points  11,12  are the Normally close contact   and points   11,14  are for Normally Open contact.

When all door contacts are closed then the relay is energized and so  points 11,14 are closed and we have signal from microcontrellers  ground to  D4  


the loop of the doors from one door to the last one is 15 meters / 49ft  (or 30 meters / 98ft  in total with the return line )



about DC voltage i am not sure if it is allowed, i will have to check it..  for sure the previous setup was based in relays with  110 ac current  from transformer   as the main power supply is 220v ac  50hz



while ago i had found in the internet (cant remember the site or the person that posted it) a schematic for 3phase sequence check .

maybe using something similar for the 110v  will be ok? and for more safety adding an Opto-isolator


meltDown

So the relay is energised by the mains? I didn't even know such relays existed, we live and learn.




caslor

So the relay is energised by the mains? I didn't even know such relays existed, we live and learn.




You have never come across to relays that use  12 , 24, 48, 110, 230 v AC  for the coil ?

meltDown

You have never come across to relays that use  12 , 24, 48, 110, 230 v AC  for the coil ?
... but then I've never needed an AC relay for anything ever in 55y of playing with electrical stuff, so it probably never occurred to me that such a thing would exist.




caslor

... but then I've never needed an AC relay for anything ever in 55y of playing with electrical stuff, so it probably never occurred to me that such a thing would exist.
Yes as an electrician i can understand that... we are used to deal with that relays for automation in older days... before microcontrollers invade :P

now that i have start learning more things about electronics i am also come across to parts that never thought that exist :)   



about my ''problem''   just discover  that are opto-isolators that work with ac voltages  like the  ''H11AA814 OPTOCOUPLER AC-IN''    that maybe will what i was looking to avoid the relay for my project

any other thoughts or suggestions ?

ReverseEMF

#11
Jul 22, 2019, 03:29 pm Last Edit: Jul 22, 2019, 03:31 pm by ReverseEMF
about DC voltage i am not sure if it is allowed, i will have to check it..  
That, to me, is a very odd statement.  It makes me wonder if there's confusion over the safety of AC vs DC.  And, that would be valid, were we talking about similar voltages.  But, I suggested 24V [or even 48V, which is on the edge of "safe" voltages].
24VDC is certainly going to be far safer than 120VAC [or above].  
"It's a big galaxy, Mr. Scott"

Please DON'T Private Message to me, what should be part of the Public Conversation -- especially if it's to correct a mistake, or contradict a statement!  Let it ALL hang out!!

caslor

That, to me, is a very odd statement.  It makes me wonder if there's confusion over the safety of AC vs DC.  And, that would be valid, were we talking about similar voltages.  But, I suggested 24V [or even 48V, which is on the edge of "safe" voltages].
24VDC is certainly going to be far safer than 120VAC [or above]. 
No No  it was not about safety of Ac vs Dc ...

But i asked and told me that now days there is not any limitation about what voltage should i use for a project like the one i described at my first post.

So i will  go for the 24v dc and  opto-isolator solution

thanks all for your suggestions

raschemmel

I assume you are not in the USA because there is a limit to voltage AC & DC that you can use without requiring safety equipment (pertains to businesses only).
The limit is 50V (ac or dc). Anything beyond that requires safety protective covers etc..
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

caslor

No i am not in USA.
I am in EU  but we have also safety limitations

for example in my  project if i want to use  voltage greater than 50v i have to add to my circuit a leakage switch

Go Up