Interlocking fans

Hi all,

I am working on a project where I have 5 x Supply fans and 5 x Extract fans and they shall run continuously.

Could you help me to write below logic or give me some guidance.

Supply fans and exhaust fans are interlocked so supply system cannot run without confirming the exhaust system is running. Supply fans should always equal the amount of exhaust fans i.e. 4 no. extract fans require 4 no. supply fans to be running.

I was thinking to have 10 x DI for FAN AVAILABLE and then 10 x DO for RUN FAN.

Thank you in advance :)

Hello AutoGen,

I don't really understand your project. If all five exhaust fans are supposed to run continuously and one fails, you just need to connect the fans of one supply and one exhaust fan together. A suitable motor protection circuit would then shut down both. You don't need a logo for that.

And besides, supply and exhaust fans don't increase the airflow in a room in any way. Either a supply or an exhaust fan would be perfectly sufficient for a room.

Best regards, Ella_68

(translated by Google)

Hi,

Thank you for your response.

I will try to explain this.

This space should maintain neutral pressure, so the supply fans should always equal the amount of exhaust fans (extract fans can run without supply fans running).

If lets say one of extract fans trips then one of supply fans should stop from running. 

For example if Supply fan 1 is not available/tripped and Extract fan 3 is not available/tripped. I would want Supply fans 2,3,4,5 and Extract fans 1,2,4,5 to run.

Each fan will have motor protection circuit and we want to be able to start each fan individually.

Thank you in advance :)

Greetings.

I've attached the input and output configuration.

To continue with the project, please confirm if the input and output configuration meets your needs.

Hi,

Thank you for your reply. Yes Inputs and Outputs seems to be fine.

I have a question, is there any counter available in Logo Soft Comfort to count Extract Fans Running Inputs and give me HIGH output if certain number of inputs are HIGH?

For example any 4 of 5 extract fans running, only "counter no. 4"  with set point of 4 would have an output high, and if 2 of 5 extract fans are running, only "counter no. 2" with set point of 2 would have an output high and so on. 

Thank you

Hello AutoGen,

Even if I were only working with exhaust fans, here's my first suggestion.

The output setup looks quite slow in the simulation. However, the Logo itself works much faster, so I assume this has some effect on the contactors. Otherwise, the outputs would have to be synchronized, which would require an additional 30 blocks.

Best regards Ella_68