Power quality terminology What is a brownout in electrical supply terms for IT equipment?

Introduction / Context:
Properly identifying power anomalies helps select protection gear (UPS, line conditioners) and troubleshoot intermittent computer failures. Among sags, surges, blackouts, and brownouts, each has different implications for electronics.

Given Data / Assumptions:

• We are using standard power-quality definitions used by facilities and IT.
• Duration is long enough to affect device operation but not a total loss of power.

Concept / Approach:

A brownout is a sustained or semi-sustained reduction in RMS line voltage below nominal, often due to grid load. It is more pronounced and longer than a transient “sag,” but it is not a complete outage (blackout). Brownouts can cause undervoltage stress, data errors, and motor overheating.

Step-by-Step Solution:

Verification / Alternative check:

UPS vendor documentation and power quality standards define brownouts as sustained undervoltage, frequently mitigated by line-interactive or online UPS topologies.

Why Other Options Are Wrong:

Elevated voltage describes overvoltage/surge. Complete outage is a blackout. Rapid cycling is different from sustained undervoltage. The statement dismissing electricity is irrelevant.

Common Pitfalls:

Confusing transient sags with brownouts; assuming a surge protector solves brownouts (it usually does not), whereas a UPS with AVR (automatic voltage regulation) helps.

Final Answer:

A slightly decreased voltage lasting seconds to minutes or more.