Relays waking up in undermined state.

This is just a heads up to share an experience I have just had with 2 relay units. I am just the programmer for this particular install and this particular install has gone a little different.

2 of the '12 channel' relay units than were installed, when first powered up - turned 'On' in an undetermined state. That is, some relays were active and the indicator lights were indicating that 'all' were inactive.
Note:- The units were stand alone in that they were not yet connected to the main C-bus network and they had not yet been programmed. (At least not by me, when I did program them, they loaded normally)

Normally this might not cause much of an issue except for the fact that these two particular units were being used as interlocks for the blinds.

From the switchboard everything seemed fine, I was with the electrician when he lived the units up. It was not until the contractor who was sanding the floor in that particular room came to find us because some of the blinds had closed and would collect dust. Checking the room we had some blinds that had operated and others humming away. That actually was a lucky break, the time was late on the Thursday before Good Friday and we were just about to leave until Tuesday.

The circuit breakers were turned off and we returned on Tuesday. Circuits were checked, the wiring was fine! Turning the breakers back on we had other blinds operate and others were now humming. The relay modules indicators all showed the inactive state. I intentionally operated the override switch on 'Relay 1', I heard the relay click but the indicator light stayed Off. Pressing the override again I heard the relay click and this time the indicator lit up to indicate an active state. I went through all overrides and other relays were in similar states.

I do not recall ever being told or finding that this might be an issue when the units were first installed and/or still not programmed. I programmed them up on Friday and have not yet attempted a power down to see how they wake up. As of today (Sunday) I do however have one blind that is partway down and does not want to go up or down, it just hums. (And that particular blind is over the door that everyone is using to enter the house.)

 

Thanks for the heads up, but surely this is a cautionary tale.

As the outputs should all be on MCBs, for relays on the switched side, they should not be turned on until the programming is done and the state is a known factor. Personally I programme, test by meter and then on with MCB.

Its a bit more laborious and in my case im lucky as im the sparky too.

Them blinds arent cheap, why chance it.

Cheers

Simon

 

It`s not really a good idea to use 12 ch volt free relays with blind control as it is possible (as you have found) to energise both the up & down relay at the same time.You need to use a changeover relay.This way the relays will be mechanically interlocked and impossible to power both feeds at the same time.Also as Amberelectrics has pointed out,It is better to program & test the circuit before connecting the blinds.Although i`m not really sure why he would put an mcb on the switched side of a relay.
As for some of the relays switching on when powering up.I would make sure these are programmed as factory default & check each local toggle to see if it opened & closed the contact with the indicator in the correct state.

 

Ooops, my bad, I meant on the common, typing faster than thinking as per usual.

 

This is a cautionary tale.
'Factory Default - We should not have to check that the factory has got it right.' I would have thought that would have been picked up when tested? (I'm not saying it was a factory error either)

The units were out of sealed boxes and sealed inside their plastic packaging.
I expected the units to have a default state, that is what surprised me. I would also expect the indicator lights to have followed the relay state, even if they woke up in a random fashion.
We have passed through seeming unscathed, I thought I would just share the experience. It might save one of you a large insurance claim.


(The sticky blind was not C-bus hardware related - now resolved.)