CDCP Data Center Power Infrastructure 4

Question 1

What is the primary purpose of a static transfer switch (STS) in a data center power system?

Accepted Answer

To transfer load between two power sources with sub-cycle switching speed

Answer

An STS transfers load between two independent power sources in less than one AC cycle (~4ms) to maintain continuous power to critical loads.

Question 2

In a 2N power architecture, if one complete power path fails, what percentage of IT load capacity remains available?

Accepted Answer

100%

Answer

In a 2N architecture, each path is sized to carry 100% of the load, so failure of one entire path leaves the other path fully capable of supporting all IT equipment.

Question 3

Which harmonic order is typically the dominant harmonic produced by six-pulse rectifiers commonly used in UPS systems?

Accepted Answer

5th harmonic (300 Hz)

Answer

Six-pulse rectifiers predominantly generate 5th harmonic (300 Hz at 60 Hz systems) as the lowest-order characteristic harmonic, which is the most problematic for power quality.

Question 4

A data center operator installs a 1500 kVA transformer with a 0.85 power factor rating. What is the maximum real power (kW) the transformer can deliver?

Accepted Answer

1,275 kW

Answer

Real power (kW) = kVA × power factor = 1500 × 0.85 = 1,275 kW.

Question 5

What does the term 'power stranding' refer to in data center power planning?

Accepted Answer

Unusable power capacity due to imbalanced phase loading or circuit limits

Answer

Power stranding occurs when available electrical capacity cannot be used because of imbalanced phases, circuit breaker limits, or cooling constraints, leaving capacity installed but inaccessible.

CDCP - Certified Data Centre Professional Practice Test

CDCP - Certified Data Centre Professional Practice Test

CDCP Data Center Power Infrastructure 4