Hello:
First of all I wish to thank to "The Hien" and 2zezito" for beeing so kind and so interested on helping me.
I'm going to try to decribe in more detail the aplication and what I need:
An AVR is an automatic voltage regulator, ie, an equipment that is used to regulate or control the excitation of a generator (alternator) in order to controll the reactive load. Normaly, it can work on two different ways: Constant power factor or constant reactive power.
Supose that we want to work on constant power factor but with diferent set-points during the thay, ie, PF=0.8 between 8AM to 8PM (during the day)and PF=1 between 8PM to 8AM ( during the night).
To work with PF=0.8 I need to aplly a voltage of 9V dc, for example, and to change to PF=1 I need to change the input voltage to 0V or 0.5V dc.This values will change every day according to the clock.
The order to change the PF from one value to other is given by a potential free contact that exists on the energy counter and that changes from close to open or viceversa depending from a signal sent throw the grid by the energy distributing company ( Like EDF infrance). Intead of a 0 to 10V signal, a 4 to 20 mA signal can also be used. This is the real aplication I need.I hope I have been clear.
I'll be very pleased if you can help.
P.S. I'm not from Vietnam, but from Portugal
beerchug
Good by and thank you
Lan