CDCS CDCS Power & Cooling Systems 1 — Questions and Answers
Question 1: What does PUE (Power Usage Effectiveness) measure in a data center?
- The ratio of total facility power to IT equipment power (Correct answer)
- The ratio of IT equipment power to cooling power
- The percentage of power used by servers alone
- The total kilowatt-hours consumed per month
Correct answer: The ratio of total facility power to IT equipment power
PUE is calculated by dividing total facility power consumption by the power consumed by IT equipment, where a value of 1.0 is perfect efficiency.
Question 2: Which UPS topology provides the highest level of power protection for critical data center loads?
- Standby (offline)
- Line-interactive
- Double-conversion (online) (Correct answer)
- Delta-conversion
Correct answer: Double-conversion (online)
Double-conversion (online) UPS continuously converts AC to DC and back, isolating IT equipment from all power anomalies and providing zero transfer time during outages.
Question 3: What is the primary purpose of a static transfer switch (STS) in a data center power distribution system?
- To convert DC power to AC power
- To provide sub-cycle transfer between two independent power sources (Correct answer)
- To step down high-voltage utility feeds
- To monitor power quality and log anomalies
Correct answer: To provide sub-cycle transfer between two independent power sources
An STS transfers the load between two independent AC sources in less than a half cycle, preventing any detectable interruption to dual-corded equipment.
Question 4: In data center cooling, what does CRAC stand for?
- Computer Room Air Conditioner (Correct answer)
- Controlled Rack Airflow Cooling
- Computer Rack Ambient Control
- Centralized Refrigerant Air Cooling
Correct answer: Computer Room Air Conditioner
CRAC (Computer Room Air Conditioner) is a unit that monitors and maintains the temperature, air distribution, and humidity in a data center.
Question 5: What is the recommended approach to prevent hot aisle/cold aisle mixing in a data center?
- Increase CRAC unit fan speeds
- Deploy containment systems to separate hot exhaust from cold supply air (Correct answer)
- Lower server inlet temperature setpoints
- Install perforated tiles throughout the entire raised floor
Correct answer: Deploy containment systems to separate hot exhaust from cold supply air
Hot aisle/cold aisle containment physically separates hot exhaust air from cold supply air, dramatically reducing recirculation and improving cooling efficiency.
Question 6: Which power distribution unit (PDU) feature allows administrators to remotely cycle power to individual outlets?
- Metered PDU
- Basic PDU
- Switched PDU (Correct answer)
- Monitored PDU
Correct answer: Switched PDU
A switched PDU allows remote on/off/reboot control of individual outlets via network interface, enabling remote power cycling without physical access.
CDCS CDCS Power & Cooling Systems 1
What does PUE (Power Usage Effectiveness) measure in a data center?