Relays, mains fail, delay.

[Lectrician]

Stretch your mind.

After all the recent power failures, I have a couple customers wanting notification of power issues.

Pretty easy, battery backed text dialler, sends a text message when 0v applied.

Use a 240v relay, it drops out, it applies 0v.

Use a multifunction timer to insert a delay.

I'm struggling to design a simple circuit that will insert a delay on failure and restore.

I want to use two trigger inputs, one to trigger a fail message, one a restore. Both delayed.

You can apply and leave 0v on the dialler, it doesn't need to be pulsed. Apply and leave it, dialler texts. It won't text again until signal removed and reapplied.

Sounds simple.

Its not! When the 240v relay looses power, you need to delay release of the 0v on the restore trigger, when it is re-energised, you need to delay reapplying the 0v trigger. I think I can do this with a latching relay.

Can't draw it at the mo.

Anyone see an obviously easy method?

 

[sparkymarka]

Why would you need a delay on power restore ? Texecom text and speech Dailer you can set inputs to send restores...

 

[Lectrician]

I don't want texts being sent unless power is back for a while, to prevent further blips sending text after text. Power never just fails and comes on cleanly, always off, on, off, on.

 

[endecotp]

You need about 3 resistors, a capacitor and a transistor.

 

[JohnW2]

Are you prepared to build (simple) electronics to do this, or are you hoping to do it with just 'electrical components'?

Kind Regards, John

 

[Lectrician]

Purely off the shelf kit. Some relays, a couple multifunction timers. Think I have a pretty simple design. Will test later.

 

[crystal ball]

If you have a few to do, one of these (240v version) will have all the functions you need, might be a bit pricey for a one off though, programming software is about £50, you can download evaluation software for free from siemens
http://uk.rs-online.com/web/p/logic-modules/8251653/

 

[bernardgreen]

This might be what you are looking for. You would need to check the response times.

http://www.medpage-ltd.com/page62.html

For those who like building things

I have a design for a mechanical system using a motor driven shaft similar to the operation of a central heating valve.,

Mains on and the motor drives the shaft to the end stop, operates a micro switch (A) and stalls.

Mains fails and the shaft returns under spring drive to the other end stop, operates a second micro switch (B)

B operates only if the mains has been off long enough for the spring return to rotate the shaft all the way back

A operates only if the mains has been on long enough ( after a long break ) to motor the shaft to the end stop.

 

[endecotp]

I have a design for a mechanical system using a motor driven shaft similar to the operation of a central heating valve.

Why not use an actual central heating valve? Water fills bucket, bucket tips over, pulls string, opens door of cage and carrier pigeon flies off with message!

 

[bernardgreen]

carrier pigeon flies off with message!

This creates the additional problem of a bird feeder to ensure the bird is fit enough to fly when needed...........

 

[Lectrician]

If you have a few to do, one of these (240v version) will have all the functions you need, might be a bit pricey for a one off though, programming software is about £50, you can download evaluation software for free from siemens
http://uk.rs-online.com/web/p/logic-modules/8251653/

Logic controllers are great, but I would need a battery backed 24v DC supply (I'm using existing supplies). It would also still need relays for the power fail inputs (you can't use 230v on the inputs). I am not just monitoring mains, but RCD outputs, so several relays either way.

I thought perhaps there would be an option off the shelf, but seems not.

I have it working on one site. Will test and see how this goes. May draw diagram at some point.

 

[crystal ball]

If you have a few to do, one of these (240v version) will have all the functions you need, might be a bit pricey for a one off though, programming software is about £50, you can download evaluation software for free from siemens
http://uk.rs-online.com/web/p/logic-modules/8251653/

Logic controllers are great, but I would need a battery backed 24v DC supply (I'm using existing supplies). It would also still need relays for the power fail inputs (you can't use 230v on the inputs). I am not just monitoring mains, but RCD outputs, so several relays either way.

I thought perhaps there would be an option off the shelf, but seems not.

I have it working on one site. Will test and see how this goes. May draw diagram at some point.

On the 230v version you can use 230v inputs, I am trialling one at the moment but admittedly have not used mains input yet but the manual says yes as long as on same phase for each module, Its got my interest might have a stab at it, the delay on failure might be a challenge

 

[Lectrician]

It would need a battery backed mains supply then.

Oddly, I was fault finding a machine yesterday with one of those with an expansion module on one side. Nothing to do with the module, an input open circuit.

 

[crystal ball]

Yes a UPS would be needed, getting expensive now

 

[Mikefromlondon]

Stretch your mind.

After all the recent power failures, I have a couple customers wanting notification of power issues.

Pretty easy, battery backed text dialler, sends a text message when 0v applied.

Use a 240v relay, it drops out, it applies 0v.

Use a multifunction timer to insert a delay.

I'm struggling to design a simple circuit that will insert a delay on failure and restore.

I want to use two trigger inputs, one to trigger a fail message, one a restore. Both delayed.

You can apply and leave 0v on the dialler, it doesn't need to be pulsed. Apply and leave it, dialler texts. It won't text again until signal removed and reapplied.

Sounds simple.



Its not! When the 240v relay looses power, you need to delay release of the 0v on the restore trigger, when it is re-energised, you need to delay reapplying the 0v trigger. I think I can do this with a latching relay.

Can't draw it at the mo.

Anyone see an obviously easy method?

I only saw this post today, Do you still need help with this? if so what sort of delay are you seeking? 5 seconds? 10 or more seconds or minutes?