Solved Using Capacitor as backup

May 8, 2012 at 09:07:50
Specs: Windows XP
Using Capacitor as backup
http://www.learningaboutelectronics...
i have doubt after reading the above site...

I have inverter and when power fails it takes around 2 sec to switch over to battery, which is enough time for computer to restart. can i use capacitor to fill that 2sec. If so, what size capacitor i should use.


See More: Using Capacitor as backup

Report •


✔ Best Answer
May 8, 2012 at 19:52:07

I have inverter and when power fails it takes around 2 sec to switch over to battery,

You need a proper UPS which will have high speed switching circuits that will detect the drop in AC power almost instantaneously and switch to backup before the AC has fully decayed. An inverter on its own isn't going to do it especially if it is being switched with a mechanical relay.

The only times capacitors are used in AC circuits is to smooth out AC ripple and in noise filters. It certainly isn't going to store any energy for longer than the length of one cycle which at 50/60 Hz is not very long.

Stuart



#1
May 8, 2012 at 09:46:45
That is probably not practical. The size of capacitor required depends on the power it must supply while discharging and the time it must do so. In the website it shows the capacitor only powering a LED which requires very little power. For your purposes you would need a much larger capacitor.

How much voltage and current does the inverter need as input to supply the load? This is of critical importance.


Report •

#2
May 8, 2012 at 12:22:55
You have all the wrong stuff.

You need a UPS not an inverter.

You can't bridge AC power with a cap. You might be able to bridge a bit of time on DC with a proper R/C or L/C circuit but 2 seconds is a bit for that normally.

Hang up and live.


Report •

#3
May 8, 2012 at 12:24:02
You computer plugs into a 110 (USA) or 240 (Europe) Alternating Current wall socket. Capacitors store up Direct Current. It ain't gonna happen.

Report •

Related Solutions

#4
May 8, 2012 at 19:52:07
✔ Best Answer

I have inverter and when power fails it takes around 2 sec to switch over to battery,

You need a proper UPS which will have high speed switching circuits that will detect the drop in AC power almost instantaneously and switch to backup before the AC has fully decayed. An inverter on its own isn't going to do it especially if it is being switched with a mechanical relay.

The only times capacitors are used in AC circuits is to smooth out AC ripple and in noise filters. It certainly isn't going to store any energy for longer than the length of one cycle which at 50/60 Hz is not very long.

Stuart


Report •

#5
May 9, 2012 at 10:52:18
Actually it would store it at half that rate since the AC voltage usually goes through a bridge rectifier and inverts the negative voltage swing to positive. At that point each positive voltage bump would be 1/25 of a second for a 50Hz signal and 1/30 of a second for a 60Hz signal.

Report •


Ask Question