Day on / Night Off - Sensor

[marconi]

https://docs-emea.rs-online.com/webdocs/07ed/0900766b807ed829.pdf

For the impulse relay by ABB if the supply voltage is interrupted before the time delay is complete, the output relay de-energizes and the time delay is reset which would shut off power to the compressor until another impulse signal.

 

[marconi]

I still do not like and I would not design using a photocell switch to control the power to machinery. The guru on the regulations for safely controlling machinery is darkwood - I suggest you contact him.

 

[Darkwood]

Regardless of how complicated or simplistic this is there is the issue you are upgrading the control system to a machine and with that comes personal responsibility, additional insurance cover requirements and a full documented risk assessment, also you will need to provide an updated wiring schematic for the new control additions as well as complying to the relevant regulations like the BS 60204-1 (2018), if you are on the ball already with all the above then fine and I will be happy to advise otherwise I would take a serious step back and think about it before doing any such work.

I would also question how controlling the compressor via daylight/darkness triggers is going to be practical. What about seasonal variations and the fact you gain and loose an hour during the year, are we to believe they only work until it gets dark?

He needs to buy a clip board and have a selected member of staff sign it off on his exit that a checklist has been done before leaving which would include switching of the compressor, I have been on over a thousand sites in my time and I have not heard about anyone having to put additional controls to a compressor due to staff incompetence, he needs to toughen up and be a boss, a clip board is vastly cheaper than upgrading the compressor controls and also he may gain a little more respect as a boss if he is seen to put his foot down.

Just my opinion on the info' provided, it just seems like the cart is leading the horse here when you have to make such decisions due to incompetent staff.

 

[pirate]

I love this!
I need a sensor that works the opposite to normal ones...
so, design the circuit, assess the load etc...
Is there a dusk to dawn sensor that switches "off" instead of "on"?
Yes...it has a relay...NC type...

Now, look at the load...
Beauty! I just need the normal sensor, then add the relay that can cope with the load...

To be fair, in a recent installation, my installer friend needed a window sensor that required a NC relay...a glorified reed switch...and had to order one from China...but it arrived, it works...
However, and not to detract from the learned opnions expressed previously, I am an amateur, an experimenter, and not an expert by any stretch of the imagination...
But it is fun!

 

[Intoelectrics]

Regardless of how complicated or simplistic this is there is the issue you are upgrading the control system to a machine and with that comes personal responsibility, additional insurance cover requirements and a full documented risk assessment, also you will need to provide an updated wiring schematic for the new control additions as well as complying to the relevant regulations like the BS 60204-1 (2018), if you are on the ball already with all the above then fine and I will be happy to advise otherwise I would take a serious step back and think about it before doing any such work.

I would also question how controlling the compressor via daylight/darkness triggers is going to be practical. What about seasonal variations and the fact you gain and loose an hour during the year, are we to believe they only work until it gets dark?

He needs to buy a clip board and have a selected member of staff sign it off on his exit that a checklist has been done before leaving which would include switching of the compressor, I have been on over a thousand sites in my time and I have not heard about anyone having to put additional controls to a compressor due to staff incompetence, he needs to toughen up and be a boss, a clip board is vastly cheaper than upgrading the compressor controls and also he may gain a little more respect as a boss if he is seen to put his foot down.

Just my opinion on the info' provided, it just seems like the cart is leading the horse here when you have to make such decisions due to incompetent staff.

I don't disagree with anything you said. It most likely will be the case that I just walk away. I just thought I consider all options available before I go back to him with what i'm willing to do.

Going back to the day light working thing. This is exactly what farmers do (well at least this one) they tend to work day light hours at this particular process.

 

[Intoelectrics]

I love this!
I need a sensor that works the opposite to normal ones...
so, design the circuit, assess the load etc...
Is there a dusk to dawn sensor that switches "off" instead of "on"?
Yes...it has a relay...NC type...

I haven't seen a photoelectric sensor available in this country with a NC relay.

Now, look at the load...
Beauty! I just need the normal sensor, then add the relay that can cope with the load...

I've considered this method and thinking about it more, my concern regardless of which way its done, I don't think its good practice to rely on having to energize a relay to shut off a machine. Loss of power or a fault to the relay whether integrated in the sensor or as a separate item would mean the switch closes and the machine could energize.

 

[Intoelectrics]

I'm not prepared to do anything that is going to be a safety concern. But I don't want to walk away without considering all options. Just because it seems out of the ordinary doesn't mean we can't exercise our imagination and try to find a simple solution that works safely. I posted this inquiry because I found it an interesting question put to me by the customer.
I certainly didn't want reply's that are judgmental and make me feel like I'm committing some sort of crime. I've been in this trade for 30 years and worked on a vast variety of electrical systems.

 

[marconi]

Intoelectrics: I certainly didn't want reply's that are judgmental and make me feel like I'm committing some sort of crime.

It was not my intention to upset you but if I have then I am sorry. I was trying to be helpful and suggested an alternative solution. Of course none of us has a monopoly on good solutions.

PS: For my solution the line feed for the stop/start/latch/overload/coil/pressure sensor circuitry of the DOL starter is provided through the NO contacts of the impulse timer. Then at the beginning of the day to start the compressor there are two button pushes required - first the impulse relay and then the start button. All buttons etcetera on the DOL starter then function as required.

 

[Intoelectrics]

Intoelectrics: I certainly didn't want reply's that are judgmental and make me feel like I'm committing some sort of crime.

It was not my intention to upset you but if I have then I am sorry. I was trying to be helpful and suggested an alternative solution. Of course none of us has a monopoly on good solutions.

PS: For my solution the line feed for the stop/start/latch/overload/coil/pressure sensor circuitry of the DOL starter is provided through the NO contacts of the impulse timer. Then at the beginning of the day to start the compressor there are two button pushes required - first the impulse relay and then the start button. All buttons etcetera on the DOL starter then function as required.

Thanks, yes your solution looks like a good option and one i will definitely consider.

You didn't upset me, no particular one person did.

I just woke up a bit tetchy this morning, so I apologise if my post seemed a bit sensitive.
I see so many times on this forum people post questions and then get beat up as though they are committing a crime when they are just simply missing/misunderstanding a point. I initially asked the question because I found it an interesting exercise. I didn't post it because I want to be judged on my knowledge and abilities.

When I first started out my mentor was building a control panel and I just stood there in awe at how he new from the top of his head how to wire it all in, I asked and he said to me "just think of everything as a switch, its either on or off" his approach was to keep things as simple as possible. This has stood me in stead for 30 years and the same approach I use with my apprentices.

I like to tackle complicated problems by finding simple solutions, where possible. Sometimes there aren't any but I enjoy the challenge of it.

 

[Darkwood]

@Intoelectrics
If my reply has come across somewhat 'judgemental' etc then this was not the intent, the forum is normally based around the BS7671 but where we have members including myself that are experienced in other areas where separate and/or additional regulations exist then we have to make sure that members are aware of the implications of undertaking such work as it may not only effect the work one undertakes but also the insurance they carry.
I do not always post in the manner that I did here as it is a case by case call, in this case it was simply the nature of the question.
This is in no way a judgement against you or your competence, it may be the case this is just a little out of your usual request and you're used to working on other machinery so just asking for available options out there, all I was ensuring was that before advice is offered that you are aware that this is a sector of the industry that is heavily regulated, has additional insurance requirements and requires additional paperwork as there is nothing in your profile to suggest you do this kind of work.
I did say that if you were on ball with all I said then no issue but just have to make sure if you appreciate that sometimes we need to make sure.
The actual job sounds a simply alteration but one needs to ensure that implicating this small alteration is done in accordance to the relevant regulations and in this case I would suggest the BS60204-1 would cover this although I cannot comment as I am waiting for the new 2018 edition to land on my doorstep as it only came out about a month ago but I am aware there are a lot of additional regulations and changes to existing so as it stands I could only advise under the 2006 edition + A1 (2009).

PS just seen your last post #24... Yes we do get people getting beat up over a simple request and we do try to curb it where possible but sometimes we need to establish the OP's position before advise is handed out to ensure we are not giving out unsafe advise, this field of electrical work just like fire detection system design and install is one such area we need to make sure we are happy the OP is aware of what they are taking on... I have seen this first hand when people don't realise there insurance simply doesn't allow them to undertake this work regardless of their competence to do so as it is moving away from standard insurance that your average sparks would have, my insurance is probably 4X that of your average cover because I work on machinery and 3ph systems.

 

[Intoelectrics]

@darkwood
Thanks for your reply I appreciate your points and concerns.
Yes I have the extra insurance cover and work in-accordance with the regulations for this industry. I now work in the industrial sector mainly and have extensive experience and knowledge on 3ph systems and machinery.
Thanks again for your advice!

 

[Darkwood]

On that note then how about a solar tracking timer, no need to run external wiring and can be easily set for holidays, days off etc although they can be a pain to program up if your not used to a certain brand.

 

[Intoelectrics]

On that note then how about a solar tracking timer, no need to run external wiring and can be easily set for holidays, days off etc although they can be a pain to program up if your not used to a certain brand.

Now that's a good idea! Is there a brand you would recommend that is simple enough to program? Any info on these would be very useful to me.

Thanks

 

[Darkwood]

Been a long time since I used them and they all can be tricky to program as is anything when you first use it, I would also consider when upgrading to consider installing indication and control options to allow the timer to be isolated and normal control operation. Personally I would be adding a PLC as a small unit would be similar cost but give the benefit of other optional inputs and outputs but you also need to decide exactly how this timer works with existing system, that's where the BS60204-1 will come into play as there are several ways to incorporate it but not all will be compliant and/or considered safe unless other measures are added or considered.
If the user were to say finish early and hit the stop option then you have to consider what that means to the timer, if it is a twist stop you don't want the timer pulling the motor straight back on when you release it or the timer doing the same when you let your finger off the stop button, a simple enough issue to get around but you end up adding more and more control gear just to allow a compliant system is what I am getting at here as you not only have a manual on option but a automated on control.

 

[Intoelectrics]

Been a long time since I used them and they all can be tricky to program as is anything when you first use it, I would also consider when upgrading to consider installing indication and control options to allow the timer to be isolated and normal control operation. Personally I would be adding a PLC as a small unit would be similar cost but give the benefit of other optional inputs and outputs but you also need to decide exactly how this timer works with existing system, that's where the BS60204-1 will come into play as there are several ways to incorporate it but not all will be compliant and/or considered safe unless other measures are added or considered.
If the user were to say finish early and hit the stop option then you have to consider what that means to the timer, if it is a twist stop you don't want the timer pulling the motor straight back on when you release it or the timer doing the same when you let your finger off the stop button, a simple enough issue to get around but you end up adding more and more control gear just to allow a compliant system is what I am getting at here as you not only have a manual on option but a automated on control.

Yes all this is exactly what I have been mulling over. I've been trying to think of a way to make it compliant and safe without over complicating things.
Thanks, I appreciate your time and advice.