CDCS Exam Dumps - EXIN EPI Certified Data Centre Specialist

PUE (Power Usage Effectiveness) is the most widely used metric to evaluate the energy efficiency of data centers. Defined by The Green Grid and adopted in ISO/IEC 30134-2, PUE is the ratio of the total facility power to the ICT (IT load) power.

Formula:

Total Facility Power includes all electrical consumption: IT, cooling, lighting, power distribution losses, UPS inefficiency, etc.

ICT Equipment Power is only the load drawn by servers, storage, and networking gear.

An ideal PUE is 1.0, meaning all power is used by ICT equipment with no overhead. Typical enterprise values are 1.5–2.0, while hyperscale operators target <1.2.

Other options are incorrect:

B represents the inverse metric, known as DCiE (Data Center infrastructure Efficiency).

C and D are partial subsystem efficiency metrics, not the global PUE.

For a UPS system in a Rating-4 data center, the synchronization of output can indeed depend on the specific settings of the UPS. Generally, such systems allow for flexible configuration where the output can be synchronized to either power feed A or B, depending on which feed is preferred for stability or redundancy purposes.

Detailed Explanation:

In dual-feed setups, such as those in high-redundancy data centers, the UPS can be set to synchronize with either feed. This ensures that the UPS maintains continuity in case one feed becomes unstable or fails. The flexibility to choose synchronization to either feed enhances the resiliency and reliability of power supply, which is critical in Tier IV (Rating-4) facilities where uptime is paramount.

EPI Data Center Specialist References:

The EPI Data Center Specialist course underscores the importance of configurable UPS systems in Rating-4 data centers, where redundancy and continuous power are critical. By allowing synchronization to either feed, the UPS can maintain the highest level of reliability, which aligns with the rigorous standards expected in such environments.

When installing overhead data cabling, it’s crucial to maintain minimum separation from power cables to prevent electromagnetic interference. Additionally, cabling should be arranged so that it does not obstruct fire detection and suppression systems, allowing for proper sensor function and suppression agent dispersion in the event of a fire.

Detailed Explanation:

Separation between power and data cabling minimizes the risk of interference and helps ensure compliance with standards for signal integrity. Proper placement relative to fire suppression systems ensures that any smoke or heat can be effectively detected, and suppression agents can be evenly distributed without obstruction from cabling.

EPI Data Center Specialist References:

EPI guidelines emphasize maintaining adequate separation between power and data cables for safety and performance and ensuring cabling does not interfere with essential safety systems in data centers.

Testing smoke sensors should be conducted according to the vendor specifications to ensure compliance with safety standards and accurate results. Vendors provide specific testing procedures to account for the sensor type, environment, and operational characteristics, ensuring that tests do not damage the equipment or provide false results.

Detailed Explanation:

Smoke sensors can vary by type and sensitivity, so following the vendor's recommended testing procedure ensures the sensors function correctly without risking sensor damage. Injecting smoke or using a self-test might be insufficient or could lead to inaccurate assessments if they do not align with the vendor's testing protocol.

EPI Data Center Specialist References:

EPI recommends adhering to manufacturer specifications for testing critical safety equipment, ensuring that tests reflect real-world conditions without compromising sensor integrity or reliability.

Aerosol sprays release particulates and residues into the environment, which can contaminate sensitive ICT equipment. Such contamination accelerates corrosion, interferes with airflow, and increases particulate levels beyond ASHRAE recommended limits.

Proper cleaning should use HEPA-filtered vacuum systems or dry wipes, not aerosols. Even odor control aerosols are disallowed in critical rooms.

Therefore, aerosol cleaning solutions must never be used.

An imbalance in load sharing between UPS systems connected in parallel can often result from unequal cable lengths to the common busbar. If the cabling from each UPS to the busbar varies significantly in length, it can lead to differences in impedance, resulting in uneven load distribution. Ensuring that cable lengths are consistent helps to balance the load sharing across the UPS systems.

Detailed Explanation:

Parallel UPS systems rely on uniform impedance to share loads evenly. Differences in cable lengths cause variations in resistance, leading to one or more UPS units carrying a disproportionate share of the load. Standardizing cable lengths ensures equal impedance, which promotes balanced load sharing and prevents one UPS from being overburdened, thus maintaining overall system reliability.

EPI Data Center Specialist References:

EPI guidelines recommend checking cable lengths when load imbalances occur in parallel UPS configurations. Ensuring equal lengths is a common method to resolve impedance issues that affect load distribution, which is critical for the stable operation of redundant power systems.

High dust levels in a computer room are often due to improperly fitted floorboards. When floorboards are not securely installed or do not fit tightly, they allow dust and particles from the subfloor to enter the room. In a data center, this can lead to high levels of dust that affect air quality and equipment performance.

Detailed Explanation:

Raised floors in data centers can accumulate dust and debris, especially if the floorboards are not properly sealed. Loose or improperly fitted floorboards allow contaminants from the subfloor to enter the data center environment, increasing the dust levels over time. Proper installation and maintenance of floor panels are essential to prevent dust infiltration and maintain clean conditions.

EPI Data Center Specialist References:

EPI training emphasizes proper flooring installation and maintenance to control air quality within data centers. Correctly fitted floorboards prevent dust accumulation from the subfloor, which helps protect sensitive equipment and maintains a cleaner environment.

Halocarbon agents such as FM-200 (HFC-227ea) and Novec-1230 (FK-5-1-12) are both defined under NFPA 2001 and ISO 14520 as clean agents, but their required design concentrations and physical properties differ. When calculating agent quantity, the minimum extinguishing concentration (MEC) and safety factor (S) must be taken into account. The S-factor is specific to each agent and reflects differences in molecular weight, density, and flame suppression chemistry.

For Novec-1230, the required design concentration is generally lower than for FM-200 (around 4.5–6% vs. 7–9%), but the calculation formula is the same except for substituting the correct S-factor. Therefore, you cannot reuse the exact formula parameters from FM-200; you must change the S-factor and apply Novec-1230’s physical constants.

This ensures compliance with NFPA 2001 Annex C, which provides correction formulas for room volume, temperature, and specific agent type. Using the wrong S-factor could result in underfilling or overfilling, compromising fire safety or increasing cost unnecessarily.