Step 7 / 14

How does a UPS (uninterruptible power supply) work?

The simplest form of the hybrid inverter: one 12 V battery, a few MOSFETs and a big transformer. Switch the state at the top (grid on, power cut, low grid) and follow the energy. Then use 'Find the fault' to track down the commonest faults by measuring.

Grid

The mains from the socket. While it's there, the UPS feeds the output straight from it and charges the battery.

Oscilloscope

Multimeter≈230 V AC

Tap a block to see what it does and what you'd measure there.

🔧 Inside the UPS: what's where?

This drawing isn't a photo; it follows the typical layout of 650–1500 VA home/office UPSs. Open the cover and you first see the battery and the heavy transformer; everything else is on one board. Tap a region.

Energy path:

Tap a region to see what it does and how to spot it on the board.

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Repair pack: 5,000 ₺, members get 10% off → 4,500 ₺. Or 1-week access for 1,000 ₺.

⚠ Safety: Unplugging isn't enough: with the battery connected the UPS can make 230 V on its own. Before opening the cover, unplug it, switch it off and disconnect the battery lead. Never short the battery terminals; the leads heat up and spark.

Next step: Step 8How does a voltage regulator work?→

Go further

From battery to high voltage: the push-pull topology Repair Workshop: find the UPS fault by measuring Next step: the hybrid inverter (the same idea, bigger)Concept: AVR, how transformer taps work Concept: dead time (the two MOSFETs must never be on together)Concept: series bulb Component: relay