[tsk1979]

I meant parallel, sorry.
The voltage in is DC, so I put in a cap in parallel.
MY circuit theory is all rusty, so can someone come with the formula and graph.
I can't use 500VA UPS because that will trip the generator(500 limit).

[anupmathur]

What's the voltage & current rating of the modem?
Or you could just plonk a 1000 mF cap of suitable voltage rating. That should do the job.

And I do not believe a 500 VA UPS will cause the genset to trip.

[tsk1979]

Originally Posted by anupmathur

What's the voltage & current rating of the modem?
Or you could just plonk a 1000 mF cap of suitable voltage rating. That should do the job.

And I do not believe a 500 VA UPS will cause the genset to trip.

Why not? Every apartment is allowed 500VA only and it trips if you draw more

[Ford Rocam]

are you using a desktop or laptop tanveer? whats the voltage & current rating of that modems power adaptor?

[filcord]

Using an UPS may cause an unintended complication. I have one that shuts off when only the ADSL modem is connected, since the load is small, the UPS thinks there is no load, and shuts down. If, on the other hand I have also the PC on, it gives a backup for at least seven to eight minutes.

[anupmathur]

Originally Posted by tsk1979

Why not? Every apartment is allowed 500VA only and it trips if you draw more

Quite possibly you mean it is some MCB that trips? Not the genset.

The 500 VA is a rating - the MAX the UPS can handle. The actual current it draws from mains will be largely dependant on the load connected to it at any given time.

[low_bass_makker]

Originally Posted by vid6639

L_B_M paaji, 1000mf? or uF? 1000mF = 1F which is a huge cap value.

If you can spend like 1000 odd bucks you should get a wipro or a proview one.

1 farad = 1000000 microfarad

Hope it clears the doubt.

Electrostatic Capacitance Converter

Originally Posted by DerAlte

I have a 1992 vintage 0.5KVA UPS that powers my modem & LAN switch at home - had replaced the batteries a while back. Must check the backup time with the current load some time.

I totally agree. Putting a UPS is the best thing. In school day I used my office UPS which had two 12 volts battery. I used it to play my classic Cosmic Amp. It was 100 x 2 watts rms at 8 ohms. It played to full output for half hours.

[anupmathur]

Originally Posted by low_bass_makker

1 farad = 1000000 microfarad

Hope it clears the doubt.

Point well taken.
Everyone has been using mF for micro-farad, I would imagine, since typing a 'µ' is not very convenient on the keyboard!

[tsk1979]

Its 5V 1A power supply. so I presume 5W is the peak power consumption. I have a APC UPS 500VA battery dead, suppose I don't connect that to generator point, and only connect modem to UPS, I think I can get 150-160 minutes of backup. Normally power cuts last atmost 3 hours at a stretch.

[anupmathur]

Yes Tanveer, that should do you fine. Keep your UPS plugged into a non-genset mains socket and feed your modem from the UPS.