Hi

Does anyone have a circuit I can use to measure mains frequency using the high speed counting input on the LOGO?

I was thinking of a step-down transformer 240vac to 24vac with a half bridge rectifier on the 24vac side but that seem very simplistic .

I am sure there needs to be some noise filtering etc.Maybe someone has already done this

Any assistance will be appreciated

Hello AutoGen,

To protect the logo, I would use an LDE-based coupler between the transformer and the logo instead of a rectifier. This must not have a bridge rectifier internally, of course.

Let me ask you a question: What do you want to build? It is quite unusual to measure the mains frequency with a PLC.

Regards Ella_68

(translated by google)

Hi

Thank you for your reply. I am already using the LOGO to monitor my 8KVa generator.

I am using 0-10v transducers for the current and the Voltage, but would like to monitor the frequency as well.

The generator is charging my solar system during poor weather and the inverter will not accept the generator input if the frequency is not within certain limits.

William

Here is a small example of the principle and a possible couple.

P.S. Have you already thought about how you want to track the generator to keep it exactly at 50 Hz ?

Regards Ella_68

Thank you very much!!

I will test the circuit

I will only monitor the frequency not control. 

I use Blynk to visualize and to send in app notifications.

William