IoT Controller: Controlling Multiple PDLC Films

[nasherrr]

Hi,
I am currently working on a project where I'm going to control the switching of the PDLC films using the Blynk app on my mobile phone. The PDLC films would require 60V ac. Thus, it would require a transformer to step down the 240V from the mains to 60V to connect to the PDLC films. I would like to ask, is it possible if I want to connect a relay module at the secondary side of the transformer in between the transformer and the films? The relay module voltage rating is 250 VAC. I attach the basic connection of my planned circuit and the relay module I'm using.

Thank you!

.

 

[betwixt]

Switching the low voltage should work exactly the same as switching the high voltage side except the current will be higher. For your application that shouldn't be a problem. However, you will have to check what power the relay board itself needs and make sure the relay switches both the lines (red and black on your diagram) or you could run into some serious safety issues. I suspect all that relay does is switch one of the three screws on the right to one of the others, you really need a module that switches two independent lines. (A double pole relay)

Brian.

 

[nasherrr]

Switching the low voltage should work exactly the same as switching the high voltage side except the current will be higher. For your application that shouldn't be a problem. However, you will have to check what power the relay board itself needs and make sure the relay switches both the lines (red and black on your diagram) or you could run into some serious safety issues. I suspect all that relay does is switch one of the three screws on the right to one of the others, you really need a module that switches two independent lines. (A double pole relay)

Brian.

Hi,
Thank you for replying! I am sorry, I actually made a mistake in the diagram. I attached the correct one along with this post. I actually have tried connecting the relay module on the secondary side of the transformer, but it doesn't work. The LED on the relay switched on and off according to the commands from the Blynk app but it doesn't switch the films along with it. Does this mean my connections have a problem?

 

[betwixt]

Yes, it should work so you have a connection problem. Most likely you have the line in and out wires connected to the relay NC and NO contacts, they should be between the Common and NO contacts. I would urge you take extreme care if you don't use a double pole relay and also make sure you use a good quality transformer. Under no circumstances use an auto-transformer whatever its ratings are.

Brian.