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Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch

Added by Jas2 over 4 years ago

Hi,

I have a automated Velux window, in a high up out of reach place, with a chain actuated motor to open and close it.
The open / close rocker control switch is a 240v ac rocker switch, located just outside the toilet on the wall.
This is the switch http://cpc.farnell.com/1/1/35103-grid-plus-switch-2-way-k4899whi-mk-electric.html.
This 240v a.c. switch has three positions as follows :

1 Switch In the middle position. Window motor deactivated. No current. Switch is sprung to always return to this position when finger pressure is removed.

2 Switch Press Up from middle position. Switch will only stay in this position while you press with your finger. Window motor activated to drive window in opening direction. Motor drives in direction A

3 Switch Press Down from middle position. Switch will only stay in this position while you press with your finger. Window motor activated to drive window in closing direction. Motor drives in direction B

It is very important that terminals for A and B cannot be connected at same time or this would kill the motor.
It is also very important that switch always defaults to central OFF after finger is removed from switch or motor would definitely burn out.

I desire relay switch for this application that will drive 20A from Jeenode with 240v output.

I have looked quite extensively though don’t know quite what I am looking for. Everything I can find seems to finish latched in drive position A or B and not OFF.

Anyone make a relay switch recommendation.

Thank you :-)


Replies (13)

Jeenode Relay switch to replace 2 way and off Velux window opening/closing mains switch - Added by martynj over 4 years ago

Jas2,

The key is to use two relays (single-pole, changeover).  These can be wired so that there is no risk of feeding the UP wire and the DOWN wire at the same time and still allow for manual override with the existing switch.
The relays need to be heavy duty  - the motor running current is probably less than one amp, but is much greater at startup or if stalled at the end of the travel.  Since the load is inductive, there is a contact arc on opening the circuit.

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by Jas2 over 4 years ago

Hi Martyn,

Thank you for ur response.

I wish to keep the hall way wall switch in place and switch this out (so that both motor polls cannot be activated at the same time) as the automation relays “come in”.

Here is what I have (attached diagram) and it will involve running another 3-core and earth behind the dry-wall (plasterboard) which I wish to avoid.

Is there a better way to achieve this ? Tried looking for a web site on relay configurations and ended up getting bamboozled by the rs-online.com site with the gazillion offerings.

Ideally a single relay in the loft would disconnect the hall way wall switch hot wires and then after safe disconnection, connect the required motor terminal via Jeenode controlled automation relays in the loft.

Any ideas ?

Thank you :)

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by Jas2 over 4 years ago

Anyone know … does a relay switch like this exist (see attached image) ?
Tried for hours to find one and couldn’t.

From my online reading it would be a
SPTT-NO, single pole triple throw-normally off (again see attachment). Needs to spring back to centre and stay unconnected when not activated.
eg this site http://en.wikipedia.org/wiki/Relay
or this site http://www.engineersgarage.com/contribution/anjali/introduction-to-different-types-of-relays

Ideally need a relay that will disconnect a wall switch which has the same function (2-way and off see previous posts for part number) and then start the automated switching …

Ideas anyone ?

Thank you :)

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by martynj over 4 years ago

Jas2,

Do you have space next to the existing switch for another deep box in the plasterboard (or a double width box?)
If so, there is no need for another cable run - you can do it all with two SPDT relays and the MCU/RF Module, but you need space for a fully isolated power supply in there as well.

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by Jas2 over 4 years ago

Hi Martyn,

Thank you for your reply.

Yes there is space.

How would this look ?

:)

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by Jas2 over 4 years ago

Hi Martyn,

Any idea how the SPDT relays would look with a fully isolated power supply.

BTW I don’t know “C” and haven’t time to learn so the MCU/RF (Jeenode?) bit will have to wait another day.
I will just get an understanding of how the relays look for now.
Jeenode is really frustrating because I’m sure if I could sit down with someone for 1-3 hrs I would be able to do almost anything with them? ok .. well … may be not anything … Is there a weekend meeting anywhere folks can go to meet up where some guys willingly pass knowledge?

Thank you :)

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by martynj over 4 years ago

Jas2,

With enough space, the power supply, Jeenode and two relays can sit adjacent to the existing switch box. Then the extra wiring is all at this level - no need to run extra cables to the motor.
The schematic has an ‘UP’ relay, a ‘DOWN’ relay - activating either automatically isolates the existing switch. If both relays are in the ‘resting’ state, then the existing switch function is restored - a useful backup perhaps while debugging. The MPU can run with a safely isolated supply, but you are still switching mains volts at the relays - the usual precautions are required !

There is no protection against excessive ‘ON’ time for the motor - you can use a timer or the stalled motor state at the end of travel could be detected by a small current transformer. The live feed should be properly fused to protect against a “crashed” node.

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by Jas2 over 4 years ago

Hi martynj

Thank you :) That is sooooo helpful :)

My thinking about the position of the jeenode in the loft was
* a rain sensor, snow sensor, wind sensor could go on it to open close the window depending on weather, and
* a humidity sensor could poke down through the bathroom room ceiling and detect when the shower was on and open the window
* .. some combination of the above two would determine when the window should be open/ closed.

Perhaps I can just put another Jeenode up in the loft and get them both to speak to the Rasp Pi. Here is all I have so far … temp in the chart shown is measured by DS18B20 temp sensors on a “1-wire” CAT3 bus wired up with CAT5e cable. No jeenode’s connected up yet except the one shown on the rasp-pi ..
http://kes2.sytes.net:3336/show\_chart\_mobile.html. The chart at the top of the page takes a moment to load.

Regards fully isolated power supply .. is this necessary to protect Jeenode and relays from surge protection ?

Thank you :)

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by martynj over 4 years ago

Jas2,

Hmm - depends what power source you have at loft level I think. The existing switch to window motor cable is S1, S2, N, E ? This doesn’t give a permanent live to power your loft sensor box unless there are more cables to tap into up there (e.g. ceiling lighting roses will have L, N, E but don’t mix the N’s)

Using a fully isolated power supply is for protection - not the components, people! It is the start of partitioning the “safe” low voltage side from the potentially hazardous mains potential side.

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by Jas2 over 4 years ago

Hi martynj

How r u ? :)

  • The window motor has wires on it’s cable tail for is S1, S2, N, E. Yes this is correct. S1 and S2 240v a.c. UK mains voltages (all wired to mains system).
  • The window motor has built in protection against excessive ‘ON’ time according to supplier. Though i always release wall switch as soon as it has reached full travel. http://tealproducts.com/work/ack4-chain-actuator/
  • I will have to spend time researching current transformer for full travel detection as I don’t really know what that does. Unless there is an obvious device choice. About 20A rating for the motor I believe. Poss 10A will work too.
  • There is a socket ring that pokes into the loft that can be used.
  • Yes. I understand that the relay / jeenode device will have two very different sides. 3.3v or 5v relay switching side and 240v ~10A switching side and that saftey is completey different for each side. Usual isolation precautions.
  • I think when U say “safely isolated supply” this means PSU (power supply unit) ie something like micro-USB wall charger for powering jeenode and that being different to mains current/ voltages switching on other side of relays or did U mean something else ? ? Yes. I think U mean something different to what I have just said, though i’ve tried googling “fully isolated power supply” and did’nt get far. May be the electric folks use a different description?
  • I need to find out how to fuse the motor against a crashed Jeenode. Thanks. Yes. That is sensible. I will ask the supplier as I don’t know what to do there.

Thank you :)

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by martynj over 4 years ago

Jas2,

From the rather sketchy description in the spec sheet, looks like the actuator is already well protected. Their implementation probably locks out the offending direction of travel (allowing the ‘bad’ supply line to stay connected without time limit) and it takes power on the other control wire to reset the lock out.
If so, there is no need to sense the motor current for the jump increase at the end of travel, it’s all done in the actuator already. The reverse is possible if the actuator lockout is as described above. You can sense for the motor current drop at the end of travel, and signal “operation complete”.

The type of power supply I mean is galvanically isolated from the mains (which basically implies a transformer in there, big for 50Hz and smaller for switched supplies). Safety implies conservative design like an earthed interwinding shield on the transformer. Most of the “made in China” plug in USB wall-warts do not comply. I would be nervous leaving one of these plugged into a socket hidden in the loft. Chose a reputable manufacturer like this one perhaps http://sg.element14.com/recom-power/rac01-05sc/ac-dc-converter-1w-5v-reg/dp/1903055

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by olNick over 4 years ago

Relays typically are break before make (BBM), but sometimes one needs make before break types….

http://www.allaboutcircuits.com/vol\_4/chpt\_4/3.html

hope this helps….

RE: Jeenode Relay switch needed to replace 2 way and off Velux window opening/closing mains switch - Added by martynj over 4 years ago

Standard break before make relays are required in the control schematic shown above.

    (1-13/13)