Quiz: Power & UPS

← Back to quiz index

3 questions

L1 (2 questions)

1. What is PUE and what is a good value?

Show answer

PUE = Total Facility Power / IT Equipment Power. 1.0 is perfect (impossible). 1.2-1.4 is good. 2.0 means half the power goes to cooling/lighting. Track PUE to find cooling inefficiencies.

2. What are the differences between basic, metered, and switched PDUs?

Show answer

Basic PDU: power distribution only (no monitoring). Metered PDU: shows total amperage/wattage per PDU (helps prevent overload). Switched PDU: remote outlet-level power control + metering (can power cycle individual servers remotely). Monitored per-outlet PDU adds per-outlet metering. Always use at least metered PDUs in production. Redundant power: each server's PSUs on different PDUs fed from different circuits/UPS.

L2 (1 questions)

1. How do you calculate power budgeting for a rack and what limits should you watch?

Show answer

Sum the nameplate wattage of all devices (servers, switches, storage). Apply a de-rating factor (typically 0.7-0.8x nameplate for actual draw). Check against circuit capacity: a 30A 208V circuit provides ~6.2kW but should not exceed 80% continuous (4.9kW). Also budget for cooling (roughly 1:1 with IT load in traditional datacenters). Watch for: phase imbalance on 3-phase power, in-rush current on startup, and peak vs average draw.