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slow voltage current builder: how to increase voltage,current in ramp manner upto the desired value?


Let us assume a system requires 230V ac, 6 amp. When we switch it on, the voltage and current instantly shoots up from zero to 230V,6amp. I want the system to receive the voltage,current slowly ,i.e, when it is  switched on, the voltage,current should increase from zero in a ramp manner ,and when it reaches 230V,6amp, it should remain there till  the system is switched off.

I am guessing you want some automated way to do this. 

If it doesn't have to be automated, one cheap and easy way to do this would be by using a triac-based lamp dimmer switch.  Then when turning the load on, the user uses the dimmer switch to turn on the load slowly.
http://en.wikipedia.org/wiki/Dimmer

Another trick I have heard/read about is something called a "inrush current limiter".
http://en.wikipedia.org/wiki/Inrush_current_limiter
This is basically a resistor which has a large resistance when it is cold,and a small resistance when it is warm. You put it in series with your load, then when you switch them both on, the current is small at first (while the limiter is cold), then builds up to a maximum value (when the limiter warms up).

Also you might want to think about:  "How slow is slow?".  How many seconds, or milliseconds, do you want to spend on this "ramp up" period.