あなたを必ず合格させるCDCS問題集PDF 2025年最新のに更新されたのは60問あります
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質問 # 25
A data center scores Rated-3 in mechanical, Rated-4 in electrical, and Rated-2 in architectural.
What is the overall Rating of this data center when the Rating is based on the ANSI/TIA-942?
- A. Rated-4 since electrical is more important than mechanical and architectural
- B. Depends on the Rating scored in telecommunications
- C. Rated-4 since that is the highest rating received
- D. Rated-2 since that is the lowest rating received
正解：D
解説：
According to ANSI/TIA-942 standards, the overall data center rating is determined by the lowest rating among all evaluated categories. Therefore, if a data center is rated 2 in architectural, despite being rated higher in mechanical and electrical, the overall rating is Rated-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.
質問 # 26
The humidity in the computer room has changed from about 50% down to 35% Relative Humidity (RH).
What influence does this have on Electrostatic Discharge (ESD)?
- A. ESD levels will go down
- B. No influence as long as the temperature is at approximately 20°C/77°F
- C. Relative humidity has no influence on ESD
- D. ESD levels will go up
正解：D
解説：
As relative humidity decreases, Electrostatic Discharge (ESD) risks increase. Lower humidity levels reduce the amount of moisture in the air, which normally helps dissipate static charges. When the humidity drops from 50% to 35%, the likelihood of static electricity accumulating on surfaces rises, leading to a higher potential for ESD incidents that could damage sensitive IT equipment.
Detailed Explanation:
ESD events are more common in dry environments because there is less atmospheric moisture to neutralize electrical charges. Maintaining relative humidity above 40% helps minimize the risk of ESD, which is why data centers often control humidity levels tightly to protect equipment from static discharge that could cause hardware failures or data loss.
EPI Data Center Specialist References:
EPI data center best practices stress the importance of maintaining stable humidity levels to prevent ESD, particularly in computer rooms. Recommended humidity ranges are typically above 40% to prevent conditions that would foster static buildup.
質問 # 27
Do you need to consider blast protection when designing a data center?
- A. Yes, if the data center is a potential target or the building is located within the vicinity of (close by) a potential target.
- B. Yes, blast protection is a requirement of ANSI/TIA-942.
- C. No, blast protection is not a requirement of ANSI/TIA-942.
- D. No, there is no reason for implementing blast protection as nobody can predict the impact of a bomb explosion.
正解：A
解説：
Blast protection should be considered if the data center or its location is a potential target or is near high-risk areas. Blast protection measures can protect both personnel and infrastructure from potential explosion impacts, which could be essential in areas with heightened security risks.
Detailed Explanation:
In areas where there may be risks of terrorist attacks or explosions due to nearby high-risk facilities, implementing blast protection measures helps safeguard the data center's infrastructure. These measures can include reinforced walls, blast-resistant windows, and secure entryways designed to withstand explosive forces.
EPI Data Center Specialist References:
While not specifically mandated by ANSI/TIA-942, EPI training advises considering local risk factors, including proximity to potential targets, when evaluating the need for blast protection. This approach is aligned with risk assessment and mitigation practices to ensure facility security.
質問 # 28
When are the wet bulb and dry bulb temperatures identical?
- A. When the dry bulb's temperature is at the highest allowable temperature for IT equipment as per ASHRAE
- B. When the relative humidity is at the best practice value for relative humidity, being 50% RH
- C. When the relative humidity is 100%
- D. When the dry bulb's temperature is at the lowest allowable temperature for IT equipment as per ASHRAE
正解：C
解説：
The wet bulb and dry bulb temperatures become identical when the relative 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.
質問 # 29
You are allowed to use a calculator for this question. The total power consumption of the ICT equipment in a rack is 6 kW. The equipment is traditional ICT equipment with a Delta-T of approximately 11 °C / 20 °F. Calculate the approximate CFM required to cool the equipment in the rack.
- A. Approximately 1,500 CFM
- B. Approximately 1,000 CFM
- C. Approximately 500 CFM
- D. Approximately 160 CFM
正解：B
解説：
To calculate the cooling airflow requirement for 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 consuming 6 kW with a Delta-T of 20°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.
質問 # 30
What indicates the breaking capacity of a fuse or breaker?
- A. Mechanical strength of the casing of a fuse or breaker.
- B. The current that a fuse or breaker is able to interrupt without being destroyed or causing an electric damaging arc.
- C. The current at which the device will trip.
- D. The maximum voltage, in case of an electrical surge, that the fuse or breaker can handle without being destroyed or causing an electric damaging arc.
正解：B
解説：
The breaking capacity of a fuse or breaker indicates the maximum current it can safely interrupt without being damaged or creating a dangerous arc. This value is crucial for ensuring that the device can handle fault conditions and prevent equipment damage or fire risks due to excessive current flow.
Detailed Explanation:
The breaking capacity, also known as the interrupting rating, ensures that the fuse or breaker can safely handle fault currents up to a specified limit. Exceeding this capacity could result in the device failing to interrupt the current, potentially causing hazardous conditions like electrical arcs.
EPI Data Center Specialist References:
EPI training underscores the importance of matching fuses and breakers with appropriate breaking capacities for the anticipated fault levels in data centers to ensure reliable and safe operation.
質問 # 31
You are working with a customer who requires a guarantee that THDi levels coming from the UPS should not exceed more than 3% THDi. Furthermore, he wants to run a power-efficient data center. The UPS has a 6-Pulse SCR/Thyristor based rectifier. The current load on the UPS is approximately 80%. The customer indicates they are not expecting any changes on the ICT infrastructure for the next 3 years.
What should you recommend?
- A. Install an isolation transformer rated at K13 or K20
- B. Install an active harmonic filter on the UPS
- C. Install a passive harmonic filter on the UPS
- D. Nothing, the UPS will be able to take care of the right levels of THDi
正解：B
解説：
Given the customer's requirement to limit Total Harmonic Distortion (THDi) to below 3% and the presence of a 6-pulse SCR/Thyristor-based rectifier, an active harmonic filter is the best solution. A 6-pulse rectifier typically generates higher harmonic distortion, often exceeding 3%, especially under substantial loads like 80%. An active harmonic filter dynamically monitors and compensates for harmonic distortion, effectively reducing THDi and supporting a more power-efficient operation, aligning with the customer's energy efficiency goals.
Detailed Explanation:
Passive harmonic filters can reduce harmonics but are less effective at maintaining low THDi levels under varying loads. Active filters offer real-time correction and can achieve lower THDi levels than passive filters, especially in systems with fluctuating loads or where strict harmonic limits are required. Installing an active harmonic filter will ensure compliance with the specified THDi limits and optimize power quality.
EPI Data Center Specialist References:
EPI guidance on power quality management recommends active harmonic filters for environments where strict THDi levels are necessary. Active filters offer better control over harmonic levels, supporting both compliance and operational efficiency.
質問 # 32
What is the main reason to install Earth Leakage protection?
- A. Protection against lightning strikes
- B. Protection of ICT equipment against high-frequency noise currents
- C. Improvement of the data center grounding/earthing system
- D. Protection of human lives
正解：D
解説：
Earth Leakage Protection is primarily installed to protect human lives by 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.
質問 # 33
Which formula is correct?
- A. Phase-to-Neutral Voltage = Phase-to-Phase voltage /1.732
- B. Phase-to-Neutral Voltage = Phase-to-Phase voltage * 1.732
- C. Phase-to-Neutral Voltage = (Phase-to-Phase voltage * 1.732) / Phase-to-Neutral Voltage
- D. Phase-to-Neutral Voltage = Phase-to-Neutral voltage * 1.732
正解：A
解説：
The correct formula for calculating Phase-to-Neutral Voltage in a three-phase power system is Phase-to-Neutral Voltage = Phase-to-Phase Voltage / 1.732. This formula applies to balanced three-phase systems, where 1.732 (or √3) represents the relationship between line-to-line and line-to-neutral voltages.
Detailed Explanation:
In three-phase systems, Phase-to-Phase Voltage is higher than Phase-to-Neutral Voltage by a factor of √3. Dividing the phase-to-phase voltage by 1.732 gives the phase-to-neutral voltage, which is critical for understanding power distribution in three-phase electrical systems commonly found in data centers.
EPI Data Center Specialist References:
EPI electrical training highlights the importance of knowing these calculations for designing and maintaining balanced power systems, which are essential for stable and efficient data center operations.
質問 # 34
A computer room with a raised floor has been designed with racks in a hot/cold aisle setup.
What should you recommend for the placement of down-flow air conditioners?
- A. Air conditioners perpendicular to (at the end of the row of) the Cold-Aisle
- B. Air conditioner placement has no influence on cooling effectiveness and efficiency. Hence, they can be placed at any convenient location.
- C. Air conditioners should always be placed at both sides of each row of racks
- D. Air conditioners perpendicular to (at the end of the row of) the Hot-Aisle
正解：A
解説：
In a hot/cold aisle configuration, placing down-flow air conditioners perpendicular to the cold aisle ensures that cool air is directed efficiently into the cold aisles where server intakes are located. This layout allows for optimal cooling performance by aligning the airflow directly with the equipment intakes, minimizing hot spots and enhancing cooling efficiency.
Detailed Explanation:
With a raised floor design, cold air from the air conditioners is supplied into the cold aisle, where server intakes are located. Positioning the air conditioning units perpendicular to the cold aisles ensures that cool air is delivered directly into these aisles, preventing air mixing and optimizing cooling. This setup takes full advantage of the airflow management strategy inherent to the hot/cold aisle configuration.
EPI Data Center Specialist References:
EPI guidelines on cooling emphasize that down-flow air conditioners should be positioned to maximize the effectiveness of cold aisle delivery, which improves cooling efficiency and helps maintain consistent temperatures across server racks.
質問 # 35
You are installing new copper cabling.
What is the advantage or disadvantage of choosing pre-terminated category 6 or 6A cabling?
- A. There is no advantage as most new copper cabling network designs are based on category 3 or 5E for horizontal cabling.
- B. Pre-terminated cabling has a higher fire rating.
- C. Pre-terminated cabling makes ordering of the copper cables more complex, as you need to know in advance on which side the male or female connector needs to be located.
- D. Pre-terminated cabling is already factory tested and saves installation time.
正解：D
解説：
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.
質問 # 36
You are working on the design of a new facility. The electrical riser of the building with high current power is located close to the area where sensitive IT equipment in the computer room will be located.
What should you recommend to reduce the amount of EMF coming from the electrical riser?
- A. Install single-phase power cabling
- B. Install three-phase power cabling based on a combined cable (e.g. XLPE etc.)
- C. Install three-phase power cabling based on three individual core wires
- D. Install bus bar trunking
正解：B
解説：
To reduce Electromagnetic Fields (EMF) emanating from the electrical riser near 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 the overall 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.
質問 # 37
What is the calculation for the desired attenuation factor for shielding material?
- A. A = M / R
Where A is Attenuation M is the maximum acceptable value R is the real value measured - B. A = 20 log (R / M)
Where A is Attenuation R is the real value measured M is the maximum acceptable value - C. You do not have to calculate the attenuation factor for shielding material as it always has the same attenuation
- D. A = 20 log (M / R)
Where A is Attenuation M is the maximum acceptable value R is the real value measured
正解：B
解説：
The attenuation factor for shielding material is typically calculated using the formula A = 20 log (R / M). This equation provides the attenuation in decibels (dB), where R represents the measured electromagnetic field strength, and M is the maximum acceptable level. The logarithmic scale helps quantify how much the shielding reduces EMF levels relative to the maximum allowable value.
Detailed Explanation:
This formula calculates attenuation by comparing the measured value with the acceptable threshold, with the result expressed in decibels. A higher attenuation indicates more effective shielding material, essential for environments requiring robust EMF management.
EPI Data Center Specialist References:
EPI standards include the use of logarithmic formulas to evaluate attenuation levels, ensuring that shielding materials provide adequate reduction in EMF to protect sensitive equipment within data centers.
質問 # 38
An MCB needs to be installed in the PDU of an air-conditioner unit.
Which breaking curve should you select?
- A. A-Curve
- B. C-Curve
- C. D-Curve
- D. B-Curve
正解：B
解説：
For an MCB (Miniature Circuit Breaker) in the PDU of an air-conditioning unit, a C-Curve is recommended. C-Curve breakers are suitable for circuits with moderate inrush currents, such as those experienced in air conditioning units. They provide protection against overloads while accommodating the inrush without nuisance tripping.
Detailed Explanation:
C-Curve breakers trip when currents exceed 5 to 10 times the rated current, making them ideal for devices like air conditioners that experience moderate inrush currents upon startup. This characteristic provides a balance between protection and resilience against startup surges, preventing unnecessary trips while safeguarding the circuit.
EPI Data Center Specialist References:
EPI guidance for data center electrical systems specifies that C-Curve breakers are appropriate for equipment with inrush characteristics similar to air conditioning units, as they help prevent operational interruptions caused by typical surges during equipment start-up.
質問 # 39
A data center requires an audit to find out whether it conforms with ANSI/TIA-942 Rated-3 (concurrently maintainable).
Will the network architecture be part of this audit?
- A. Yes, amongst other aspects, the network architecture should be Rated-3 compliant with the requirements of ANSI/TIA-942.
- B. No, only the type of cabling used will be audited.
- C. No, as concurrently maintainable only applies to electrical and mechanical (power and cooling).
- D. Yes, but only if the network administration does not comply with ANSI/TIA-606.
正解：A
解説：
For a Rated-3 data center, network architecture is indeed a key component of the audit under ANSI/TIA-942. This rating requires concurrent maintainability across 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.
質問 # 40
You are allowed to use a calculator for this question. A battery bank is rated at a total capacity of 600 Ah. Calculate how much charging current the rectifier should be able to supply as charging current.
- A. 60 Amperes
- B. 30 Amperes
- C. 12 Amperes
- D. 80 Amperes
正解：B
解説：
To determine the charging current for a battery bank, a general rule of thumb is that the charging current should be 5% of the total battery capacity. For a battery rated at 600 Ah, this calculation would be:
600 Ah×0.05=30 Amperes600 \, \text{Ah} \times 0.05 = 30 \, \text{Amperes}600Ah×0.05=30Amperes This ensures the battery is charged efficiently without overloading the rectifier or risking battery damage.
Detailed Explanation:
Battery charging current is typically set as a percentage of the battery's capacity to balance effective charging with longevity and safety. A 5% charging rate is standard for lead-acid batteries, which would be 30 Amperes for a 600 Ah battery bank.
EPI Data Center Specialist References:
EPI standards recommend calculating charging currents based on a percentage of the battery capacity to ensure safety and efficiency, aligning with best practices for battery management in data centers.
質問 # 41
What is the advantage or disadvantage of using MPO (Multi-fiber Push On)/pre-terminated fiber?
- A. It speeds up installation and provides an easy upgrade to transmission speeds up to 40 Gbit/s -100 Gbit/s.
- B. It is a very flexible system as it can be used for both copper cables and optical fiber cables.
- C. There is no advantage, as it creates additional heat load in the data center.
- D. There is no advantage, as it cannot be used with OM4 optical fiber cables.
正解：A
解説：
MPO (Multi-fiber Push On) pre-terminated fiber offers the advantage of quick installation and supports high-speed upgrades up to 40 Gbit/s and 100 Gbit/s. This technology simplifies connections by allowing multiple fibers to be connected in a single plug-and-play module, reducing installation time and making future expansions or upgrades to higher speeds easier.
Detailed Explanation:
MPO connectors consolidate multiple fiber connections into a single interface, which simplifies cable management and reduces installation complexity. This setup is particularly beneficial in data centers where high-speed networks are essential, and where rapid deployment is necessary. MPO pre-terminated fiber also supports the use of OM4 fiber, making it compatible with existing high-performance cabling infrastructure.
EPI Data Center Specialist References:
EPI training highlights that pre-terminated fiber solutions, like MPO, can greatly enhance efficiency in data centers. By reducing installation time and providing scalability for higher transmission speeds, they align with best practices for maintaining flexible and future-ready network infrastructure.
質問 # 42
The computer room has high levels of H2S gas contamination. What is the best option to resolve this issue?
- A. Vacuum the whole room using a HEPA/S-Class-based filter.
- B. Provide more air changes per hour by adding more fresh air to the computer room.
- C. Clean the room and racks with a damp/wet cloth.
- D. Install air-scrubbers.
正解：D
解説：
High levels of H2S (hydrogen sulfide) gas contamination in a computer room are best addressed by installing air-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.
質問 # 43
The pipes of a VESDA smoke detection system are installed at the air intake of the air conditioner inside the computer room.
Is this a good practice from an early smoke detection point of view?
- A. No, it will give a longer reaction time for the smoke detection system and there might also be bypass airflow.
- B. Yes, as this reduces the amount of piping to be installed in the data center, as all air will go through the air conditioner.
- C. No, the piping should be installed at the air exhaust of the air conditioner, as there can also be a fire inside the air conditioner itself.
- D. It depends on the type of gas-based fire suppression which will be installed.
正解：A
解説：
For optimal early smoke detection in a data center, it is crucial that the Very Early Smoke Detection Apparatus (VESDA) system be installed at locations where smoke will be detected as soon as it appears. Positioning the VESDA pipes at the air intake of the air conditioner inside the computer room is not ideal. This placement could result in a delayed detection response and the potential for bypass airflow to occur, which would impede the system's ability to detect smoke effectively.
Detailed Explanation:
When VESDA pipes are installed at the air intake, the detection system relies on the smoke to be drawn into the air conditioning unit before detection can occur. This setup increases the reaction time as the smoke has to travel through the intake and get processed by the air conditioner. Furthermore, bypass airflow-a phenomenon where not all the air containing smoke particles passes through the VESDA pipes-could also delay or even prevent the system from detecting smoke early.
Ideally, VESDA pipes should be positioned where smoke is likely to accumulate first, such as near the ceiling or in the return airflow path to detect smoke at the earliest possible stage. This ensures that the detection system can quickly trigger alarms, providing more time to address potential fire hazards.
EPI Data Center Specialist References:
EPI Data Center Specialist training highlights that smoke detection should prioritize early response capabilities to maximize safety. The preferred installation for VESDA pipes is generally at points where smoke would naturally accumulate, rather than relying on air conditioning intakes where airflow can vary and delay detection. In their course materials, EPI emphasizes minimizing reaction time and reducing the impact of airflow dynamics on smoke detection efficiency.
質問 # 44
You have three UPS systems connected in parallel. The UPS systems have an imbalance in the load sharing of approximately 20%.
What should you recommend?
- A. Review the common mode noise levels within the computer room
- B. Review the cable lengths of each UPS to the common busbar
- C. Nothing, there is no reason for any concern
- D. Review the harmonics levels within the computer room
正解：B
解説：
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.
質問 # 45
Do you need to consider bullet (ballistics) protection when designing a data center?
- A. Bullet (ballistics) protection is only required when the data center is located in an area with a high crime rate.
- B. Bullet (ballistics) protection is required by ANSI/TIA-942 for data centers Rated 3/4.
- C. Bullet (ballistics) protection is only required if the facility is a potential target or the building is in the vicinity of a potential target.
- D. Bullet (ballistics) protection is required by ANSI/TIA-942 for all data centers.
正解：C
解説：
Bullet (ballistics) protection is typically considered only for data centers that are potential targets or located near such targets. While ANSI/TIA-942 does not specifically require bulletproofing for all data centers, it is prudent to consider it based on location risk assessments, especially if the facility is in a high-risk area or near critical infrastructure that could attract threats.
Detailed Explanation:
Protective measures like bulletproofing depend on the threat landscape and the data center's exposure to risks such as crime or terrorism. Assessments for physical security are typically customized based on location-specific risks rather than being universally required by data center standards.
EPI Data Center Specialist References:
EPI guidelines emphasize customizing physical security measures based on threat assessments, suggesting that bulletproofing is appropriate in specific circumstances where the facility's risk profile justifies additional security measures.
質問 # 46
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2025年最新のの問題CDCS問題集を試そう！更新されたEXIN試験が合格できます：https://drive.google.com/open?id=1B26hSyut6vvoiURzQ9hdL9pNDoUa4G9w