OFFLINE UPS

i've college assignment to design OFFLINE UPS. Unfortunately we dont have good guidence at college. I'm also eltrx newbie in design.

Plz Suggest some links. Also guide me step by step how to proceed.

Specifications:
1) 500VA
2) o/p= 230 V quassi-square
3) battery:24V, 7.5A backup time: 30 mins.
(from this we can get VA and AHr. rating of battery)

Features/Indicators:
1) Charging
2) Battery starts trickling
3) overload trip indicator (with time condn, should not trip immediately, wait few seconds)

4)MOSFET f/b isolation (whats this ??? :?: )

Plz reply back.
regards,
Neil.

500W 24V is 21A! From 7,5Ah battery cannot suck this current over 10..12min...

What the hell is an offline UPS. That's a redundant statement. UPSs are designed to operate offline. When the power cuts out, the UPS supplies power to whatever is plugged in to it until its batteries are drained. Please clarify your project.

Types of UPS OFFLINE, ONLINE

3 types of UPS:

1)ONLINE: aka Inverter prefered, In this load is always connected thru UPS system/invetrer (UPS S/w: Normally ON s/w). And Mains s/w is Normally OFF. hence mains is connected only when UPS fails.
Protection Circuit: 1) over vtg and under vtg cutout.
2)overcurrent protection
Advantage of ONLINE: isolation betn load and mains ac supply, henece popular.



2)OFFLINE: aka Line Prefered, Mains s/w: Normally ON and UPS s/w: Normally OFF hence UPS coes into ckt only when Mains supply fails.
changeover time is there abt 5ms or less.

Protection Circuit: 1) mains over vtg
2) o/p overcurrent protection
3) Low battery

3) Line interactive UPS: Similar to offline . schematic is different. battery and charger posn changed. will try to upload schematic in 2-3 days.

Re: Sebi

read specs again:
500VA
7.5A
30 mins.
therefore, AH rating= 7.5A*30mins = 3.75 AH.

helful info.

thanx neil , was helpful info abt UPS. never knew there r 3 types