UPS backup for vacuum bagging system?

[Tisr]

Hi guys

I'm putting together a vacuum bagging system for bagging composite glider wings.

The system consists of the usual fridge compressor, reservoir and vacuum switch and relay. The pump should only run for about 30 seconds every ten minutes or so. Because I will be using this sytem in PNG where we regularly get power blackouts, I'm trying to come up with a power backup system. This is fairly critical since the wing must stay under vacuum for 24 hours.

My question is, do you think a computer UPS would be capable of supplying what I need?

Thanks for your input

Dan

[octane-link]

A computer UPS only lasts 5-10 minutes, enough to save and properly shut down your computer.

You would be better off with something like an emergency generator. How long do your blackouts last? If you have properly sealed the bag, it should hold pressure for a couple hours before enough air leaks out to cause problems.

[Tisr]

Thanks for the advice. We do actually have a back up generator for our workshop for use during the day, but unfortunately not at night...

Just wondering whether the UPS has to be under load when the power fails in order to keep running or is it possible to start something up using it after the power is off? Does anyone know what sort of startup current a compressor that is rated at 155W would draw?

Dan

[Chippie]

As far as I know, the inrush current on start up is usually around 7 times the full load current...Thats the figure we use at work when setting overload devices in our switchgear...so if you got a 155w motor on a 220v supply? then that should pull somewhere in the region of 0.7 amps, so you are looking at around 5 amps on startup.

Your ups needs to supply something like that...