Roller Blinds Motor Tripping RCD

Well I need some input about a porblem I am having

first the basics,

I have a 12 channel relay to control 4 Elro roller blinds, and 1 Projector screen
from the blinds I get 4 wires, Neutral connected to common neutral, Ground connected to common ground, and the and active up and active down wire, those are connected to two sepreate relay channels
so If I turn on channel one the curtain goes up, and turn that of and channel 2 on the curtain goes down.
I have one 10A MCB for each relay channel

this basicly works, BUT !!! a short while after the install I started getting every now and then failures that would trip the RCD, thus knocking the whole house out

this would happen evary now and then and not follow any regular pattern
after trying to analyze this and trying to find some common factor I notced that most of the time when the RCD is tripped one curtain has reached it stop point at the top or bottom, I.E the builtin limiter kicks in and stops the motor.

this just seems to happen with the blinds, not the projector screen

any thoughts or suggestions on what to try ?

p.s. I have checked all the connections, which are all right, and there is no moisture or any such issues near the curtains

 

I was taught that motor,especially muliple motors, tripping RCD is normal. Just use MCB should be good enough, unless you have some other channels connected to sockets.

 

Rcd

ok will look into that

can any of you that have connected curtain motors to cbus relays confirm that it?s standard to connect them not to a RCD

thanks.

 

We always use multiple RCD/CB combos on our installations so if a tripping does occur, it only takes out a small proportion / section of the house, and not the power to the whole house. More importantly you do not have to go around and reset 20 digital clocks in various devices within the home.
Yes it does cost more to install an average of 6 to 20 of these devices (depending on size of the installation and loadings) but the convenience of not losing the whole house to a genuine triping or false triping far outways the additional costs of supply and installation, and once the pros and cons are explained to the clients they also see the added benefits. Servicing of equipment is also easier and has less impact on the owner as you isolate sections of power as opposed to all of the power off to the complete home. One faulty device / component doesn't then render the whole house useless until the service organisation attends site, and most of these incidents always occur outside of normal hours which renders the clients home useless and turns the client into an agressive and angry person requiring your immediate attention and attendance to his prediciment regardless of whether it is a genuine fault or one made of his wrong doing.
We have always run RCD on blind and curtain circuits and has never presented a problem provided you have sufficient lockout time between change of direction counted in seconds not milliseconds.

Just my 2 cents worth as I hate seeing a whole house protected with only 1 RCD device.

PS. I am normally the bunny who has to reprogram every digital clock as the clients are normally too lazy, can't remember or can't find the manuals after the triping.

 

Still a problem

Well I still have this problem and am racking my brain to try to find a solution

I have tried to connect the Blinds motors on the outside of the RCD but when using the blinds the RCD is still tripping

any ideas would be welcome

thanks

 

What about

What about using Contactors ? Another CBUS user (Mr Locke) uses them for some outside lights he has that were previously tripping.

G.

 

Hi

Try connecting the blinds to their own RCd which will hopefully trip instead of tripping the main RCD for the house. The fault may not b e in the blinds either, there may be another fault that has been introduced after the installation of the blinds.

If the main house RCD continues to trip after you install a separte RCD on the blinds, I would be looking elsewhere for the fault.

Make sure you connect the new blind RCD outside the main house RCD.

Hope this helps some.

Regards
Brett

 

Thanks for all the info

can you explain one thing to me

what is the diffrence in a contactor and a Relay ?

most of the info I find on the web about contactors is about
large industrial ones

thanks
Arni

 

A contactor basically *IS* a relay

Normally the only dhe difference is that "relay" has Low Voltage control, while a "contactor" uses Mains Voltage control

So, a relay is usually powered by low-power (eg: 12V DC) control device, and has contacts inside it that switch a higher-powered load (eg: 10Amp 240Volt)

With a contactor, the input is (say) 240v AC, and it switches a (also) 240V load. So the contactor is used to replace a normal mains switch - it removes the load from the switch, normally to reduce it's size.

In large industrial applications you might want to switch a 3 phase motor that draws 20A per phase. The manual switch to do that would be huge and ugly - so a contactor is used that has 3 poles (1 for each phase). A small normal 240V switch is used to control the contactor, and the contactor's (big) relay contacts then turn on the motor.

That was probably a very bad explanation

JC

 

Have found through ( bad ) experience that with out a reasonable delay, driving the blinds one way then the other either trips the CB or worse still fuses the relay contact. From research through the 'net, most blind motor suppliers seem to have settled on a 0.5 sec delay. Minute, but seems to solve the problem.

Mark

 

Hi John

Most contactors we use these days have 24v dc coils as 24dc is the standard control voltage in most industrial equipment......You can also source relays with 240v coils........Bus as you say contactors are normally used for 3 phase loads and relays generally anything up to 240v and under approx 10 amps.....

HTH
Frank

 

ok so its like I thougt, the Contactor is just like a relay, driven by 240V

I have been using relays like that with this setup, to guarantee mechanical interlocking, and the RCD was still tripping

The next thing for me to try is I think to put the curtain motors on a spereate RCD, but even though now they are not protected by the RCD it?s still tripping

it just happens when they reach the top or bottom, and the limiter in the curtain motor kicks inn, it?s like it send some kind a pulse when that happens, that will Trip the RCD

 

There is something VERY wierd going on to trip those RCDs... The way they work is to detect the current on Active and Neutral, and when there is a difference in that current then the RCD trips.

There can't be a current imbalance in a proper "normal" circuit, because the power goes "up the active" and a matching amount comes "back the neutral". However if there is a leakage to earth (or another phase, or to anywhere) an imbalance is created between the power in the Active and Neutral, which trips the RCD.

Take a careful look at how the curtains are wired up... Over Christmas I found a problem when I fitted individual RCDs in my own house. There was 2 lighting circuits that continually tripped the RCD's and I spent hours determining why - in the end I had to re-wire a whole section of the house to resolve it.

It turns out that some prior electrician had joined the Neutrals of 2 circuits - so at the switchboard there was 2 pairs and at the other end there were 2 pairs, but in a junction box in the ceiling the 2 neutrals were joined. In a normal wiring system this didn't cause any problem at all, since the Neutrals were both connected together at the switchboard anyway.

But in my case, when I installed an RCD on each of those circuits, they always tripped ! The reason was that the current went "up the active" but only 1/2 came back on the corresponding neutral, because the other 1/2 of the current returned on the other neutral.

So, take a careful look at the interlocking circuits, etc. Make sure that you haven't inadvertantly brought in another neutral. Also check the back EMF from the motors - there might be a capacitor or something in there which is causing a spike of power in some circumstances? Maybe there is a capacitor between active or netral and earth (for RFI suppression) and that is causing the leakage. Perhaps the motor is using dynamic braking or something wierd?

Also, test the motors after removing all your controls from the equation... in other words, wire it up completely "standard" so that you can determine if it's the motors or the controls that are causing the problem - also contact the curtain motor manufacturer, as at the end of the day it is there product which is causing the problem.

Good luck, John

PS: Electricians please don't comment on my (incorrect) terminology about power "up the active" and "back the neutral"

 

Well it seem I am finaly rid of this problem, I changed out the RCD I had for a new one, and that seems to have done the thrick, i.e. faulty RCD

atleast it has not tripped yet, crossing finger

THANKS for all your help and sugestions, I dont know what I would do with out this list

beacuse as far as I know I am the only one in Iceland with a Cbus setup, so there is not a lot of local help to be had

Cheers

 

You realise that you're rapidly becoming the "defacto" C-bus representative for Iceland ?

In future we will refer all technical requests from that country to you, and you can drive over there (in winter by sled or snowmobile instead?) to their place and solve the problems !

Cheers, John

 

Just a note

A late reply to some things said above:

YES, there is a capacitor between the up and the down wire on the inside of the motor. Anything between 3-10 Microfarad, so its quite big and adding several motors, switched, in one group can cause quite some voltage spiking/ feedback on the line
This is especially true should the motors be connected in parallel (which is NOT allowed on most blind motors) as the spike will run from one motor via the other motors capacitor.