How to monitor the power level?

[ltg]

Power monitoring how-to?

Hi,

In my project I have to monitoring 230V AC if it is disappear or it is at low level. Could any expert please give same tips? Thanks in advance!

Best Regards,
ltg

 

[exata]

power monitoring

If you need only to know when power is lost then you can monitor it using an opto-coupler (4N25) connected to the mains (use a large value resistor in series). If you need to know the amplitude then the better way is reading it through a small transformer.

 

[Bagster]

The cheapest and most easiest must be a bridge rectifier and a potential divider/comparator. A LM358 will be very cheap and you can run it from the rectified mains (within its supply limits). Configure it as a window comparator and you will be able to tell if it is hi or low.

Regards

Bagster

 

[agknayak]

I think using LM358 directly would mean a series resistor to drop the 230V to a smaller voltage. This series resistor would be quite dissipative. I would actually suggest using a small transformer and then monitoring the secondary of the transformer.
Gopal.