Exin CDCS EXIN EPI Certified Data Centre Specialist Exam Practice Test

To determine the required capacity of the battery bank for the 15-minute runtime at full load, one must know the total power requirement that the battery bank must supply. The specifications provided include most of the necessary details, such as rated power, input voltage, battery voltage, and discharge voltage. However, one critical piece of information is missing: theUPS efficiency.

Detailed Explanation:

In a data center UPS system, the battery bank is designed to supply power for a set duration when there is an input power failure. TheUPS efficiencyaffects the actual power the UPS can deliver to the load compared to the power it draws from the batteries. The efficiency factor is necessary to accurately calculate the required capacity of the battery bank since it determines how much input power is needed from the batteries to supply the load at full capacity. The formula typically used to determine battery capacity involves factoring in UPS efficiency, as it allows you to understand the losses within the UPS system.

If UPS efficiency is not considered, there would be an inaccurate estimation of the actual power needed from the batteries. For instance, if a UPS has 90% efficiency, only 90% of the power drawn from the batteries reaches the load. Without knowing this efficiency, it is not possible to calculate the battery bank size accurately, as you cannot accurately estimate the losses within the UPS itself.

EPI Data Center Specialist References:

According to EPI Data Center Specialist training, understanding theUPS efficiencyis essential for battery sizing. Without it, the calculations could lead to either undersizing or oversizing the battery bank, which affects both reliability and cost-effectiveness of the UPS system. The EPI Data Center Specialist course emphasizes that battery sizing must account for all losses within the UPS system, with efficiency being a primary factor in these calculations.

For a cooling audit in a data center, it is essential to measure temperature and humidity where air enters the servers to accurately assess cooling performance. In this case, since all servers have afront-to-rear (F-R) airflow design, measuring at thefront/intake of the serverwill provide a precise understanding of the cooling conditions that the equipment is experiencing.

Detailed Explanation:

Servers with a front-to-rear airflow design draw in cool air from the cold aisle at the front, which is then exhausted into the hot aisle at the rear. By measuring temperature and humidity50 mm/2inches from the front intake, you gather data on the air conditions right before it enters the servers, providing an accurate representation of the cooling environment as it directly impacts the equipment.

Measuring in the cold aisle at the front intake ensures that the readings reflect the actual conditions of the incoming air that the servers depend on for effective cooling. This approach is consistent with best practices for maintaining thermal conditions in a data center, as it helps confirm that the cooling systems are delivering air within the required temperature and humidity specifications.

EPI Data Center Specialist References:

According to the EPI Data Center Specialist curriculum, the optimal placement for temperature and humidity sensors is at the intake of the equipment in the cold aisle, as it directly correlates to the environmental conditions affecting the servers. This positioning allows for a more effective audit of cooling performance, which is critical for maintaining the reliability and efficiency of the data center’s operations.

When installingoverhead data cabling, it’s crucial tomaintain minimum separationfrompower cablesto prevent electromagnetic interference. Additionally, cabling should be arranged so that it does not obstructfire 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.

Earth Leakage Protectionis primarily installed toprotect human livesby detecting and disconnecting power when a fault current flows to the ground. This type of protection is essential to avoid electrical shock hazards that could occur when insulation fails, or equipment is improperly grounded.

Detailed Explanation:

Earth leakage currents can occur due to insulation faults or accidental contact with live parts. Earth Leakage Protection systems, such as Residual Current Devices (RCDs), quickly detect these faults and disconnect the circuit to prevent harm to personnel. This is especially crucial in environments like data centers where high-powered equipment is continuously running and any electrical fault can pose significant safety risks.

EPI Data Center Specialist References:

EPI emphasizes that human safety is paramount in data center operations. Proper grounding and leakage protection are fundamental safety measures, and EPI guidelines align with this focus, underscoring the importance of protecting personnel from electrical hazards through appropriate safety systems.

To reduceElectromagnetic Fields (EMF)emanating from theelectrical risernear sensitive IT equipment,three-phase power cabling in a combined cable(such as XLPE) is effective. Combined cabling helps reduce EMF by keeping the conductors tightly packed, which minimizes magnetic fields generated by current flow. Cables like XLPE (cross-linked polyethylene) also offer better insulation, which helps mitigate EMF interference with nearby IT equipment.

Detailed Explanation:

Using a combined three-phase cable reduces EMF because the magnetic fields generated by each phase tend to cancel each other out when in close proximity. This arrangement helps reduce theoverall magnetic field strength. In addition, XLPE and similar materials provide good insulation, making them a preferred choice for reducing EMF emissions around sensitive equipment.

EPI Data Center Specialist References:

EPI data center best practices recommend mitigating EMF interference through combined cabling arrangements, especially near areas where sensitive IT equipment is located. Reducing EMF is crucial to maintaining equipment reliability and ensuring compliance with safety standards.

High levels of H2S (hydrogen sulfide) gas contaminationin a computer room are best addressedby installingair-scrubbers. Air-scrubbers can effectively filter out contaminants, including corrosive gases like H2S, ensuring clean air circulation and protecting sensitive IT equipment from potential corrosion and damage.

Detailed Explanation:

Air-scrubbers are designed to remove various airborne contaminants and are particularly useful in environments where corrosive gases are present. These systems use filters or chemical reactions to neutralize harmful substances, making them ideal for data centers that need to maintain high air quality for equipment reliability.

EPI Data Center Specialist References:

EPI guidelines suggest air-scrubbing technologies to remove contaminants that pose risks to electronic equipment, maintaining air quality and reducing corrosion risk.

According toANSI/TIA-942 standards, the overalldata center ratingis determined by the lowest rating among all evaluated categories. Therefore, if a data center is rated2in architectural, despite being rated higher in mechanical and electrical, the overall rating isRated-2. This approach ensures that all aspects meet a minimum standard and prevents a higher rating if any critical area does not comply.

Detailed Explanation:

ANSI/TIA-942 evaluates data centers across several areas, including mechanical, electrical, architectural, and telecommunications. The overall rating reflects the lowest rated category, ensuring that no aspect of the data center’s design or operation falls below the specified level. Thus, in this case, the architectural rating of 2 dictates the final rating, ensuring a comprehensive and balanced assessment of reliability and resilience across all aspects.

EPI Data Center Specialist References:

EPI Data Center Specialist training aligns with ANSI/TIA-942, stating that the final rating must reflect the lowest score to ensure comprehensive reliability across all critical infrastructure categories. This avoids overstating the data center's resilience and ensures uniform standards across areas.

Choosing pre-terminated category 6 or 6A cabling provides several advantages, primarily related to time savings and reliability. Since pre-terminated cables are factory tested, they ensure consistent quality and performance, reducing the need for additional testing during installation. This makes installation faster and more efficient, which can significantly reduce labor costs and deployment times.

Detailed Explanation:

Pre-terminated cabling systems are manufactured and tested in controlled environments, which ensures they meet industry standards for performance. This factory testing process minimizes the likelihood of faults, reducing the need for troubleshooting and retesting on-site. Moreover, pre-terminated solutions can help to streamline installations because they eliminate the need for on-site terminations, which can be time-consuming and require skilled labor.

This is especially beneficial for data centers, where rapid deployment and minimizing potential points of failure are critical to maintaining uptime. However, it is important to note that pre-terminated cables require accurate planning, as lengths and connector configurations must be predetermined.

EPI Data Center Specialist References:

According to EPI Data Center Specialist guidelines, pre-terminated cabling is advantageous in data center environments due to reduced installation time and enhanced reliability from factory testing. These attributes align with best practices for efficient data center management, where maintaining performance and minimizing downtime are priorities.

WithHalocarbon fire suppression systems, as thetemperature increases, the amount of gas required for effective suppressiondecreases. This is because Halocarbon agents are stored as a liquid and discharge as a gas, expanding more at higher temperatures. As a result, less agent is needed at higher room temperatures to achieve the desired concentration for fire suppression.

Detailed Explanation:

Halocarbons rely on specific volumetric concentrations to suppress fires. Higher temperatures cause the agent to expand more rapidly, effectively filling the protected area with less agent needed to reach the required concentration. This is in contrast to some other gases, where temperature changes might not have the same effect on discharge quantities.

EPI Data Center Specialist References:

EPI data center training on fire suppression indicates that understanding the physical properties of agents like Halocarbons is key for correct system sizing. As the temperature rises, the gas expands more readily, thus requiring adjustments in the amount needed for effective coverage.

Thewet bulb and dry bulb temperaturesbecome identical when therelative humidity reaches 100%. At this point, the air is fully saturated with moisture, meaning it can no longer absorb additional water vapor. As a result, the rate of evaporation decreases, and there is no difference between the dry bulb and wet bulb temperatures.

Detailed Explanation:

The dry bulb temperature measures the air temperature, while the wet bulb temperature takes into account the cooling effect of evaporation. When relative humidity is at 100%, the air has reached its saturation point, and no further evaporation occurs. This causes both the wet bulb and dry bulb thermometers to display the same temperature reading. This condition is critical in understanding environmental conditions, particularly in HVAC and data center environments, where humidity control is essential to avoid equipment overheating or corrosion.

EPI Data Center Specialist References:

The EPI Data Center Specialist training includes understanding humidity levels and their impact on data center environments. Knowing when wet bulb and dry bulb temperatures align helps data center operators manage moisture levels effectively, which is essential for preventing issues related to high humidity, such as condensation on IT equipment.

EMF shieldingis most effective when installedclose to the source of the EMF, which in this case is thetransformer room. Shielding at the source contains the magnetic fields before they spread, minimizing exposure throughout the facility, including the computer room.

Detailed Explanation:

Placing shielding close to the EMF source minimizes the area impacted by electromagnetic interference, as it reduces the distance over which the EMF can spread. Shielding materials near the source can absorb or redirect EMF, providing the most effective reduction of EMF levels in adjacent spaces, like the data center.

EPI Data Center Specialist References:

EPI data center training advises positioning shielding close to the EMF source to contain fields more effectively and reduce interference in critical areas. This method is more efficient and cost-effective, as it limits the spread of EMF from the point of origin.

In areas with frequent and extended power outages,continuous generatorswith at least anN+1 configurationare necessary to ensure consistent power availability. Continuous generators are designed for prolonged operation, making them suitable for scenarios where utility power is frequently unavailable, as in this case with outages exceeding 650 hours per year. An N+1 configuration ensures redundancy, which is critical for maintaining uptime in a high-availability data center.

Detailed Explanation:

Continuous generators provide reliable power over long durations, unlike standby generators, which are intended only for short-term use. The N+1 configuration ensures that there is always an additional generator available in case of failure, thus maintaining power supply even if one generator goes offline.

EPI Data Center Specialist References:

EPI best practices recommend continuous generators with redundancy for data centers located in areas with high power instability to maintain reliability and continuous operation.

To calculate thecooling airflow requirementfor ICT equipment, you can use the formula:

CFM=Power (kW)×3160ΔT(°F)\text{CFM} = \frac{\text{Power (kW)} \times 3160}{\Delta T (\text{°F})}CFM=ΔT(°F)Power (kW)×3160​

For equipment consuming6 kWwith aDelta-Tof20°F:

CFM=6×316020=948≈1,000 CFM\text{CFM} = \frac{6 \times 3160}{20} = 948 \approx 1,000 \, \text{CFM}CFM=206×3160​=948≈1,000CFM

Detailed Explanation:

This formula provides an estimate of the cubic feet per minute (CFM) of air required to cool the equipment based on its power consumption and the temperature difference (Delta-T) between intake and exhaust. The Delta-T represents the cooling effectiveness of the airflow.

EPI Data Center Specialist References:

EPI recommends using this calculation for determining airflow requirements in data centers, ensuring that cooling systems are adequately sized to maintain equipment within safe temperature limits.

For aUPS systemin aRating-4 data center, the synchronization of output can indeeddepend on the specific settingsof the UPS. Generally, such systems allow for flexible configuration where the output can be synchronized to eitherpower 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 theresiliency 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.

Raised floor tiles with air deflectors or louversare typically heavier than standard tiles due to the additional materials and mechanisms used to direct airflow. The added weight can pose challenges for installation and adjustment, and consideration must be given to the floor’s load capacity and ease of maintenance.

Detailed Explanation:

Tiles with deflectors or louvers help direct airflow, enhancing cooling efficiency by focusing cool air where needed. However, these tiles are often heavier, which can affect handling and require reinforced raised floor systems. It's essential to factor in the weight for any floor tile replacements or installations to ensure they are compatible with the raised floor's structural capacity.

EPI Data Center Specialist References:

EPI data center design training mentions the potential impact of heavy tiles on floor handling and load capacity. Data center operators need to plan for safe handling and load-bearing capacity when using such specialized tiles.

The amount of FM200 gas required can be calculated using the formula:

Weight of Gas=Net Volume×Design Concentration×S-Factor\text{Weight of Gas} = \text{Net Volume} \times \text{Design Concentration} \times \text{S-Factor}Weight of Gas=Net Volume×Design Concentration×S-Factor

Using metric units:

Net Volume: 2,500 m³

Design Concentration: 7% (or 0.07)

S-Factor: 0.1359

Calculation:

2,500 m3×0.07×0.1359=821.325 kg2,500 \, \text{m}^3 \times 0.07 \times 0.1359 = 821.325 \, \text{kg}2,500m3×0.07×0.1359=821.325kg

Rounded to the closest answer:820 kg

In imperial units:

Net Volume: 88,287 ft³

S-Factor: 1.885

Calculation:

88,287 ft3×0.07×1.885=1,165.27 lbs88,287 \, \text{ft}^3 \times 0.07 \times 1.885 = 1,165.27 \, \text{lbs}88,287ft3×0.07×1.885=1,165.27lbs

Rounded, this is approximately1,800 lbs.

EPI Data Center Specialist References:

EPI instructs on using specific formulas and S-factors provided by manufacturers for each gas type, ensuring that calculations reflect the correct concentration for the given room volume.

For aRated-3 data center,network architectureis indeed a key component of the audit underANSI/TIA-942. This rating requiresconcurrent maintainabilityacross all systems, including telecommunications infrastructure. The network architecture must therefore meet specific redundancy and reliability standards to ensure uninterrupted operations during maintenance or failure of any single component.

Detailed Explanation:

Rated-3 requirements extend beyond electrical and mechanical systems to include network architecture. This ensures that telecommunications systems are also designed for concurrent maintainability, thus contributing to overall uptime and resilience.

EPI Data Center Specialist References:

EPI endorses comprehensive assessments for Rated-3 facilities, emphasizing that network systems must meet standards for redundancy and concurrent maintainability, which align with ANSI/TIA-942’s holistic approach to data center reliability.

Inseismic-prone areas, cables should betightly securedto racks and cable trays to minimize movement during seismic activity. Properly securing the cables prevents them from being damaged due to excessive motion, which could lead to outages or damage to connected equipment.

Detailed Explanation:

Loose cables can be vulnerable to shaking or sudden jolts during an earthquake, increasing the risk of disconnection or damage. By tightly organizing and securing cables, you ensure they remain in place, even during significant movement, thereby maintaining connection integrity and reducing the risk of physical damage.

EPI Data Center Specialist References:

EPI training includes considerations for data centers in seismic zones, advising that cables be firmly anchored to support structures to reduce movement and mitigate potential damage during seismic events.