24v DC Blind control using shutter control

Hi All,

I would like to use the CBUS shutter blind control to control the following

http://www.intelli-blinds.com/docs/rollerkit_basic.pdf

Essentially its a 24v motor that need the polarity reversed to change direction of the blind.

I think the CBUS unit handle this but I am confused in the instructions for the unit

http://www2.clipsal.com/cis/__data/page/2127/L5501RBCP_C-BusShutterRelay-Installation.pdf

that it seems to need 2 power supplies and that you join the +ve and -ve together (page 7, figure 2 ) ?

Thanks
Chris

 

The instructions are correct. You can use a Shutter Relay for DC motors but you need to use two power supplies.

The Shutter Relay doesn't have the ability to flip the polarity of a single power supply. When the unit is used with DC motors, it connects one supply to the motor with positive polarity to open the blinds, and the other supply to the motor with negative polarity to close the blinds.

There is a DC termination label supplied in the box that you should affix to the unit when using DC motors so that the terminals are correctly labeled.

The "PT-18" power supply looks like a fairly generic plug-pack so hopefully obtaining a second one won't be an obstacle.

 

This is something that I have done just last week, I used it to control some venetian blinds and also a tv lifter. The motors were all wired with a 2 core cable and to reverse the direction of the motor it was neccessary to reverse the polarity of the supply. I was initially stumped but managed to find a solution by searching DC blind control on this forum. Basically what I did was use the outputs of the blind controller to switch the contacts of 2, 2 pole N/O-N/C relays. On each relay the positive feed was wired to one COM terminal and the negative feed was wired to the other COM. On the output side the N/O of the positive and the N/C of the negative terminal were bridged together. You now have an up relay and a down relay whose coils are switched by the blind controller. Then connect one leg of your motor cable to the N/C negative of the up relay and the other leg to the N/C of the down relay. In the un-energised state you will have negative-negative at the motor and therefore no movement. Activate the up output of the blind controller and this will switch the up relay giving you positive-negative at the motor. Activate the down output of the blind controller and this will give you negative-positive at the motor and therefore the opposite direction of travel. If by chance both relays are energised this will give postive-positive at the motor and no movement. I left the changeover delay at 0.5 sec and everything worked like a beauty. I enclosed everthing in a 4 module MCB enclosure and used relays that had the coil terminals on one side and the contact terminals on the other so that I could keep 240V on the top side of the enclosure and 24 volt on the bottom side with both entering from opposite sides of the enclosure.

 

Wow - thanks for the quick reply ! Do you happen to have a link (e.g RS / Farnell) to the relays you used ?

Thanks again
Chris

 

The relays I used were by NHP but any would do so long as the terminals were orientated such that you could maintain seperation of the two supplies, they must also be 2 pole with one N/O and one N/C contact. By the way it was not my original idea but one I found using the search function on this forum.