Computer Maintenance · Beginner level

Beginner level · Module 4: Preventive Maintenance · Lesson 2 of 3

Power Protection

Protect equipment from surges, outages and unstable power.

In this lesson you will

  • Choose surge protection and a UPS
  • Size a UPS for a workstation

Key concepts

surges and outagessurge protectorsUPSwatts and VA

The lesson

Power surges and sudden outages damage equipment and corrupt data. Surge protectors absorb spikes; a UPS also provides battery power during outages.

Size a UPS by the load in watts and the run time needed to save work and shut down. Check both the watt and VA ratings.

Keep UPS batteries healthy: they wear out and typically need replacing every few years.

Step by step

  1. List the devices to protect.
  2. Add up their watts.
  3. Choose a UPS rating.
  4. Estimate run time.
Worked calculation

Sizing a UPS for a workstation

Adding up the load and estimating how long the battery will last.

A desktop, monitor and Wi-Fi router (illustrative power figures)
ItemWorkingAmount
Desktop computertypical working load120 W
Monitorfrom its label25 W
Wi-Fi routerfrom its adapter15 W
Total load120 + 25 + 15160 W
Minimum VA rating160 W ÷ 0.6 power factor≈ 267 VA
Usable battery energy12 V × 9 Ah × 80%86.4 Wh
Estimated run time86.4 Wh ÷ 160 W × 60≈ 32 minutes

Explanation

A common 600 VA unit rated around 360 W comfortably covers the 160 W load and the 267 VA minimum, leaving headroom.

Thirty minutes is enough to save work and shut down — or to ride out short outages. Run time falls as batteries age, so test it every few months and replace batteries when it drops.

Check your understanding

86.4 ÷ 160 = 0.54 hours ≈ 32 minutes.

Practice activity

Size a UPS for the office workstation.

Expected result: A justified UPS choice with run-time estimate.

Check your understanding

  1. What does a UPS add beyond a surge protector?

    Show answer

    Battery power during outages.

  2. What two ratings should you check on a UPS?

    Show answer

    Watts and VA.

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