Electric Blinds

Hi Guys,

I am getting a lot of conflicting advise regarding how to approach the installation and programming of electric blinds via CBUS. One bit of advise I recently received from Somfy was not to use CBUS to supply power to the blinds via a change over relay because the change over relay can accidentally send power from both channels when powering up in the event of a power failure. If this was to occur then the onus to replace the motors would be on the installer not on Somfy and I am guessing not on Clipsal either.

Can someone point me to where I can get the definitive answer on how curtain control is to be structured and programmed that will eliminate the possibility of the above scenario occurring.

I am also interested in how others have addressed the installation and programming (via a CTC) if you care to assist a fellow installer.

Incidentally, Somfy did suggest I use a CBUS dry contact device to give up and down commands, but to use MOCO relays to supply power. Has anyone got any comments on this please ?

 

Jesmond,

A C-Bus Change-over relay with two channels electrically interlocked is the best solution all round until the C-Bus blind controller is released. That way it is impossible to power the up and the down sides of the motor at the same time. Just remember to put a 1 second delay when going from either the up > down or down > up command.

My recommendation would be order the blinds as 240v control only and supply the power from C-Bus.

 

Nick & PSC,

Firstly thanks for your comments and advise, it is really appreciated. We have installed blinds on 3 other projects using change over relays, I suppose I got a bit alarmed with what the manufacturer had told me and was not sure what the effect on the blinds be in the event of power up after a power outage.

In this particular project, the client has already got change over relays installed, and is now planning on buying the blinds over the next few weeks. He told me which motors he has been quoted on and that is where is discussion was kicked off.

Unfortunately I was called in to finish off the job that another contractor gave up on, and I just need to cover my butt !!!

 

This low level approach has always bugged me so I went searching and found a solution that uses an RS232 interface into its own bus system that can handle way more blinds than a house has windows. You could quite easily use a PAC with this to control any and all. The best part is that the units are small and can fit inside the wall at the blind itself so you dont have to run 4core cable everywhere.

Mick

 

And would you be prepared to share this particulat but of information?

 

Electronic Solutions
http://www.elec-solutions.com/docs/motor_controls/interior_ac.html

The RQ range of controllers are two way - ie they will feed back drape position so you know it is either open or closed or part way.

There is a distributor in Melbourne and both the US and Melbourne people have been very helpful and very responsive.

Mick

 

Thanks for that, interesting stuff.

 

Hi there,

we are one of the suppliers for motors to the blind/ shutter/ door industry. I have to make a few comments on the above (mostly quite correct) discussion:

- Until now, there is still no blind controller available from C-bus (it is in testing but not released as I understand. Please correct/ notify me once it is out. I AM monitoring a lot of discussion)

- Which means before, the C-bus was required to drive the motor directly with home made control solutions, nothing off the shelf.
I came across C-bus the first time in Singapore (I think 1998) and was since then asking Clipsal to look into the matter of making a dedicated Blind controller! (As ALL bus systems in Europe having that mostly for a long time!)
(Clipsal still does not have a proper Hardwired switch for Blinds... The one that is (mis-)used as blind switch has no respect whatsoever for the switchover delay)

- A number (I do not say all, there ARE some very smart programmers out there) of C-bus integrators did not read the motor manual, did not contact us for any advise, (some couldn't even read circuit diagrams!) etc. which resulted in a lot of damaged motors because of incorrect wiring and/ or programming of the C-bus/ Blind motors.
(A large number of Integrators still do not know how to properly program C-Bus for direct connection to Blind motors, they simply use dry contact interfaces. If you do not believe me, ask around!)
BTW: There are still manuals floating around, distributed by Clipsal(!), which suggest hooking up a motor directly to a switch-over relay. Not great.

- When a motor is damaged/ does not work any more (this can happen up to 3 years after the installation went on-line! Motor damage doesn't have to happen straight away!) there is always the issue to find out WHAT went wrong. All finger mostly point to the Blind installer (our customer) who mostly does not have the technical expertise to comment on programming of C-Bus and it's possible dangers to the motor.
With C-Bus programming being changed so easily, a earlier programming fault can only be found out by taking the motor apart, and looking at the limit switch contacts (which CAN give a clue of a motor being incorrectly controlled since contacts will be burned!). But of course, proving it is not a motor fault costs a lot of time/ money that no one gives us back!

- For this very reason, we usually recommend our customers (blind installers or wholesalers) to go for a dry contact solution. This can easily be trouble shot, even by the end-user, as some controller feature manual operation button and isolation switch to switch C-bus input off.
In this way, if the blinds move if manual buttons are pressed, it is a C-bus matter.
If motor doesn't move, it is a blind installer matter.
This makes it very easy (and less costly!) to the End user, plus it almost guarantees to the motor supplier C-Bus did not damage the motor.
(Although, we had cases of people wiring 240V to our dry contact low voltage interface inputs, this just shows what is going on out there!)

- Despite all of the above problems, we always have approved of direct connection of C-bus to the Blind motors AS LONG the 3 basic wiring/ programming rules are/ can be followed (also see attached document) which are:

1: No parallel connection of motors (there are some exceptions, but few)

2: No up and down power activation at the same time. Which has to be achieved by HARDWARE interlocking, not Software interlocking
(Some electronic limited motors will not be damaged, but could loose their limits that way, since this triggers the limit setting mode)

3: A switchover delay between the up and the down direction of at least 0.5 seconds (Which has to be ensured even if blinds are operated from different locations at the same time. I.e. Timer moving blinds down, User trying to override in up, what happens with time delay)


I believe that most motor suppliers would agree with me on above points, as the technical requirements of the AC asynchronous motors used in the blind industry are very similar.


As for ease of connection, motor features:
Our company actually does have a motor for the SMI system (joint cooperation of a number of Motor and Control manufacturer, including heavy weights like ABB).
Find more info here: www.smi-group.com (Clipsal (or everybody else by that matter) is free to join!)
This system was originally developed by elero (known then as DMI) and is already available for a number of years, representing the 3rd generation for motors designed specifically for integration into Building Management systems.
(I was involved in the very first large installation of the 1st generation in 1997, we controlled over 1600 blinds, by 24 sun sensor to drive to 255 position, able to monitor each blind position on a monitor and feedback if motor are damaged, etc. In the KL SC Building (Malaysia, Kuala Lumpur)

The current system can control (via 1x RS 232 or dedicated Building management system interface) up to 16 motors individually all connected via 1x 240V 5-core cable (robust communication, 200m no problem, no shielded/ special cable required!)

Some motor features (Available from 5 different motor manufacturers!):
- Drive to 65635 positions (By inbuilt encoder NOT timer, way more accurate) in height
- Drive to 65635 positions for tilt (for Venetian Blind motors only)
- Recall any of these positions
- Slow drive command available for some motors (drive at reduced speed, i.e. for Venetian Blind tilt)
- Poll motor status (overheated, position reached, mechanical block, etc)
- Alarm possible (for roller shutters: Someone trying to force the shutter open, motor can send a signal that it is manually moved)
- and many more features

So there are solutions out there (for quite some time) that offer way more than what most people require. Just because the largest in the Industry (Somfy) doesn't have them, doesn't mean they are not available elsewhere

One downturn of this motor: price.
But why is the price so high?
The 1st Generation motors had a lower price. Integrators not knowing what they done messed up the job (That even happened in Germany, where Building automation is more widespread and advanced, even found in a number of ready made homes), always requiring the motor supplier to investigate and correct other peoples mistaked!
So all 5 motors manufacturers slowly put their prices up to cover their advisory and travel costs as well.
I wished there where more people out there who actually would RTFM (sorry, I had to say that).
Unfortunately, most people IN THIS FORUM are looking for help and advise and probably are the wrong people to tell this. All the Cowboys out there not looking for advise or not reading the manuals would be the right people to address some of this to, but how to get through to them???

Although, having said price: The less wiring that is involved, only one interface box per 16 motors and all the extra features still makes this a very reasonable product.

Just some fruits for thought

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Gee, only after posting this I realized HOW long that one gotten...