CDCS無料試験学習ガイド！（更新された122問あります)
CDCS問題集にはEPI Data Centre認証済み試験問題と解答
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質問 # 21
What indicates the breaking capacity of a fuse or breaker?
- A. Mechanical strength of the casing of a fuse or breaker.
- B. 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.
- C. The current that a fuse or breaker is able to interrupt without being destroyed or causing an electric damaging arc.
- D. The current at which the device will trip.
正解：C
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 # 22
What is the effect of having a damper (in open position) construction in a raised-floor tile?
- A. Dampers can be used when there is a high rate of temperature change in the computer room
- B. Dampers reduce the air volume by approximately 10%
- C. Dampers increase the air volume by approximately 10%
- D. Dampers allow for a higher supply air temperature
正解：B
解説：
Perforated tiles with integrated dampers are common in raised-floor data centers because they allow airflow regulation at the rack level. However, even when the damper is fully open, the mechanism inside the tile restricts airflow. This typically reduces the delivered airflow by around 10% compared to a non-dampered tile of the same type.
* Option A is incorrect because dampers do not affect supply temperature; they only throttle volume.
* Option B is wrong since dampers cannot increase volume-they only add resistance.
* Option D is partially true that dampers help with temperature balancing, but the main effect (in open position) is volume reduction.
Thus, the technical impact of dampers in open position is a slight airflow reduction, usually quantified as
~10%.
References: ASHRAE TC 9.9 - "Airflow Management in Raised-Floor Environments," ANSI/TIA-942-B §6.
5 (Cooling Infrastructure).
質問 # 23
Management requests a 15-minute battery bank at full UPS load. UPS specs:
* 30 kVA, PF 0.8
* Battery 384 V (192 cells), end discharge 308 V
* Inverter PF 0.8, 400 V output
What information is missing to perform the calculation?
- A. Inverter efficiency / output PF
- B. Load imbalance
- C. UPS efficiency
- D. Available battery charging current
正解：C
解説：
Battery sizing requires determining the real power demand of the UPS. With 30 kVA at 0.8 PF, the real load is 24 kW. To calculate required ampere-hours for 15 minutes of runtime, we need:
Where P = load, t = runtime, V = battery voltage, and # = UPS efficiency.
Without UPS efficiency, we cannot know actual DC load on the batteries. A UPS with 90% efficiency will require more battery capacity than one with 95%. None of the other listed parameters (PF, imbalance, charging current) are critical for runtime capacity calculation.
References: IEEE Std 1188 (VRLA Batteries), IEC 62040-3 (UPS performance), ANSI/TIA-942-B §6.2.
質問 # 24
You need to install a highly sensitive fire detection system. The data center has a high airflow rate. Which system should you recommend?
- A. Dry pipe sprinkler system
- B. Photoelectric smoke detector
- C. Ionization smoke detector
- D. VIEW (Very Early Warning) smoke detector
正解：D
解説：
Data centers typically have high airflow environments due to CRAC/CRAH units, containment, and raised floors. Standard smoke detectors (ionization or photoelectric) often fail to detect incipient smoke because the air movement disperses particles.
The correct solution is VESDA/VIEW (Very Early Warning) smoke detection systems, which use aspirating smoke detectors (ASD). These systems continuously sample air through pipes and can detect smoke particles at concentrations as low as 0.001% obscuration/m. This provides early detection well before fire growth, allowing mitigation without system shutdown.
* Dry pipe sprinklers (A) are suppression, not detection.
* Ionization detectors (B) are sensitive to flaming fires but unreliable in high-airflow environments.
* Photoelectric detectors (C) are better for smoldering fires but still inadequate in high airflow compared to ASD systems.
References: NFPA 75 §5.4.3, NFPA 76 (Telecom facilities - aspirating systems), ISO 7240-20 (Aspirating Smoke Detectors).
質問 # 25
The building in which the computer room is housed is required to have a sprinkler system. The building is therefore equipped with a wet pipe system.
What action, if any, should you recommend for the computer room?
- A. Maintain the current wet pipe system.
- B. Replace the wet pipe system with a dry pipe system.
- C. Replace the wet pipe system with a deluge system.
- D. Replace the wet pipe system with a pre-action system.
正解：D
解説：
In computer rooms, replacing a wet pipe system with a pre-action system is advisable. Pre-action systems provide additional protection by requiring two triggers (e.g., heat and smoke) before water is released, minimizing the risk of accidental discharge and water damage, which is crucial for safeguarding sensitive IT equipment.
Detailed Explanation:
Wet pipe systems contain water in the pipes at all times, which poses a higher risk of accidental discharge. Pre-action systems, however, only fill the pipes with water upon detection of a fire, reducing the risk of water-related damage due to leaks or malfunctions. This approach is considered best practice for environments housing sensitive electronic equipment.
EPI Data Center Specialist References:
EPI advises using pre-action fire suppression in data centers to reduce risks associated with accidental water release, providing a safer and more controlled fire response that better protects critical infrastructure.
質問 # 26
How is the PUE ratio calculated?
- A. Total Facility Power ÷ Total ICT Equipment Power
- B. Total ICT Equipment Power ÷ Total Facility Power
- C. Total UPS Input Power ÷ Total UPS Output Power
- D. Total Air Conditioner Input Power ÷ Total Air Conditioner Output Power
正解：A
解説：
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.
References: ISO/IEC 30134-2 (KPIs - PUE), The Green Grid White Paper #49, ANSI/TIA-942-B §7.3.
質問 # 27
What is the minimum requirement for power feeds to a Rated-4 data center (ANSI/TIA-942)?
- A. Two feeds from one substation
- B. One feed split into two distribution boards
- C. Two feeds from two different substations, one power company not acceptable
- D. Two feeds from two different substations, one power company acceptable
正解：D
解説：
A Rated-4 facility requires dual active utility feeds, each from an independent substation, but they may come from the same utility provider if substations are geographically separate and independent.
* Option A is too strict; ANSI/TIA-942 does not mandate two different companies.
* Options C and D do not provide true independence and would fail Rated-4 requirements.
Thus, the minimum is two substations, possibly same provider.
References: ANSI/TIA-942-B §6.2 (Utility Service Requirements).
質問 # 28
Do you need to consider bullet (ballistic) protection when designing a data center?
- A. No, there is no reason for implementing bullet protection as you cannot predict the type of weapons that might be used
- B. Yes, but only when the data center is built in an area with a high criminality rate or with a risk of terrorist attacks
- C. No; bullet protection is not a requirement of ANSI/TIA-942
- D. Yes, bullet protection is a requirement of ANSI/TIA-942 for Rated-3/4 data centers
正解：B
解説：
ANSI/TIA-942 requires a risk assessment-based approach to physical security; ballistic protection is not mandated but may be justified by threat analysis.
* A is incomplete (it may still be required by risk).
References: ANSI/TIA-942-B §6.4 Physical Security (threat/risk assessment), ISO 31000 (risk management).
質問 # 29
FM-200 is phasing out as a halocarbon gas and management has decided to replace this with the more environmentally friendly Novec-1230 gas. Should you use exactly the same formula and parameters to calculate the gas content for the Novec-1230 gas?
- A. Yes, as long as you use the same units of measure (kg/m³ or lbs/ft³)
- B. Yes, if you take the difference between the net and gross volume into account
- C. Yes, if you change the S-factor of the formula to reflect the gas type used
- D. Yes, as long as the temperature in the computer room has not changed
正解：C
解説：
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.
References: NFPA 2001 §5.4 (Agent Quantity), ISO 14520-5 (FK-5-1-12 properties), EXIN DCS Study Guide: Fire Suppression.
質問 # 30
A computer room with raised floor and hot/cold aisles is designed. What is the minimum required distance between the air-conditioner outlet and the first rack?
- A. None
- B. 180 cm (6 ft)
- C. 120 cm (4 ft)
- D. 60 cm (2 ft)
正解：C
解説：
To ensure uniform air distribution, there must be a buffer zone between CRAC/CRAH discharge and the first row of racks. Industry best practice (ASHRAE & TIA-942) specifies at least 1.2 m (4 ft).
* Less than 1.2 m risks air velocity hotspots and turbulence, disrupting cold aisle containment.
* More than 1.8 m wastes valuable floor space without added benefit.
Thus, 120 cm is the recommended minimum.
References: ANSI/TIA-942-B §6.5.3 (CRAC placement), ASHRAE TC 9.9 Thermal Guidelines.
質問 # 31
What is needed to determine the Relative Humidity (RH)?
- A. Dry bulb temperature, wet bulb temperature, and psychrometric chart
- B. Dry bulb temperature, airflow, and conversion table
- C. Cold surface with dew collection counter
- D. Wet bulb temperature, local atmospheric pressure, and calculator
正解：A
解説：
Relative Humidity (RH) is defined as the ratio of the actual water vapor content in the air to the maximum possible water vapor content at a given temperature. To calculate RH:
* Dry bulb temperature (DBT): the ambient air temperature.
* Wet bulb temperature (WBT): the temperature measured by a thermometer covered with a wet wick, influenced by evaporative cooling.
Using DBT and WBT, the humidity ratio and dew point can be determined with a psychrometric chart or Mollier diagram. From there, RH is calculated as:
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Options A and B are incomplete, while option C is an experimental method, not standard practice. The recognized method is option D.
References: ASHRAE Fundamentals Handbook - Psychrometrics, ISO 7726 (Measurement of Physical Quantities in Thermal Environments).
質問 # 32
What is a potential disadvantage of using water mist as a fire extinguishing system?
- A. It will rapidly increase the humidity level in the data center, which can cause a potential risk for the operation of the equipment
- B. It has droplets that are too small (100-120 microns) so it can only be used for small fires
- C. It extracts oxygen from the air creating a potential risk for humans inside the computer room
- D. It only uses 10% of the water normally used in a water-based fire suppression, which might not be enough to suppress the fire
正解：A
解説：
A potential disadvantage of using a water mist fire suppression system is that it can rapidly increase the humidity within the data center, which may pose risks to sensitive electronic equipment. Excessive humidity can lead to condensation, which could damage electronics and lead to short circuits or corrosion over time.
Detailed Explanation:
Water mist systems use fine droplets to suppress fires by cooling and displacing heat. However, the moisture generated may raise the humidity level to the point where it exceeds safe operational limits for IT equipment.
Therefore, while water mist systems are effective in fire suppression, they may not be ideal in environments where high humidity could damage sensitive equipment.
EPI Data Center Specialist References:
EPI guidelines advise considering the impact of humidity from fire suppression systems, particularly in environments housing electronic equipment. It's essential to weigh the benefits of fire suppression against potential risks to operational equipment when choosing suppression methods.
質問 # 33
Three data centers are benchmarked on facilities energy efficiency.
Data center A has achieved a PUE of 2.45.
Data center B has achieved a PUE of 1.20.
Data center C has achieved a PUE of 1.90.
Which of the data centers is operating at the highest facility efficiency?
- A. Data center A
- B. Data center C
- C. Data center B
- D. PUE does not indicate efficiency
正解：A
解説：
A Power Usage Effectiveness (PUE) of 1.20 (achieved by Data Center B) indicates the highest facility efficiency among the three data centers. A lower PUE value signifies better energy efficiency, as it means that a greater proportion of the total energy consumed is used directly for IT equipment rather than for cooling, lighting, or other facility needs.
Detailed Explanation:
PUE is calculated as the ratio of total facility energy to IT equipment energy. A PUE close to 1.0 suggests that almost all the energy is dedicated to computing processes, with minimal overhead. With PUE values of 2.45, 1.20, and 1.90, Data Center B (1.20) operates most efficiently by devoting a higher percentage of its total energy to IT equipment.
EPI Data Center Specialist References:
The EPI curriculum emphasizes PUE as a key metric for data center efficiency, with lower values representing better performance. Achieving a PUE near 1.0 aligns with industry best practices for energy-efficient data center design and operation.
質問 # 34
What is a disadvantage of hypoxic-based fire suppression?
- A. Gas containers must be close to hazard
- B. Only usable with positive pressure rooms
- C. Only usable in rooms with sufficient air changes
- D. Only usable in non-occupied areas
正解：D
解説：
Hypoxic systems continuously lower oxygen concentration (~15%) to prevent combustion. While safe for short-term human exposure, standards like ISO 20338 recommend they are not suitable for continuously occupied spaces, because reduced oxygen may cause fatigue, reduced cognition, and health risks for staff.
* B is irrelevant-air change rates affect dilution, not feasibility.
* C is incorrect-tanks can be remote.
* D is false-positive pressure is not required.
Thus, the main disadvantage is restriction to non-continuous occupancy.
References: ISO 20338 (Oxygen Reduction Systems), NFPA 770.
質問 # 35
What is the sensible heat ratio (SHR)?
- A. Ratio of the sensible heat to the total of sensible plus latent heat to be removed from a conditioned space
- B. Ratio of the cold-aisle temperature to the hot-aisle temperature
- C. Ratio of cold-air supply to hot-air return temperature of a cooling system
- D. Ratio of the latent heat to the total of sensible plus latent heat to be removed from a conditioned space
正解：A
解説：
SHR = Sensible Load / (Sensible + Latent Load); it describes the portion of the total cooling that is sensible (temperature change) versus latent (moisture removal).
References: ASHRAE Fundamentals Handbook (Psychrometrics/Load Calculations), ASHRAE TC 9.9.
質問 # 36
The humidity in the computer room has increased from about 60% up to 85% Relative Humidity (RH). What potential risk does this pose to your equipment?
- A. No risks at all
- B. The electrostatic discharge (ESD) levels will go up
- C. The risk of excessive wear and corrosion will increase
- D. There will be a cooling risk due to a high wet bulb temperature
正解：C
解説：
High relative humidity (above 80%) creates a serious risk for corrosion of electronic contacts, printed circuit boards (PCBs), and metallic components. Moisture in the air condenses more easily, especially when surfaces are cooler than ambient dew point. This can lead to oxidation of connectors, degradation of solder joints, and eventual failures in ICT hardware.
Electrostatic discharge (ESD) risks, by contrast, increase at low humidity (below 30%) because dry air promotes charge buildup. Therefore, option C is incorrect here. Similarly, option D (cooling risk from wet- bulb temperature) applies to evaporative cooling efficiency, not directly to ICT risk.
ASHRAE recommends data centers maintain RH between 40-60% for optimal reliability. Values above 80% RH are considered outside the recommended operating envelope and significantly increase the risk of corrosion, especially in the presence of airborne contaminants like sulfur dioxide (SO#) or hydrogen sulfide (H#S).
Therefore, the verified risk at 85% RH is corrosion-related degradation.
References: ASHRAE TC 9.9 Thermal Guidelines (2016 Edition, Table 4.1), IEC 60721-3-3 Environmental Conditions for ICT Equipment.
質問 # 37
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 # 38
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 1,000 CFM
- B. Approximately 500 CFM
- C. Approximately 160 CFM
- D. Approximately 1,500 CFM
正解：A
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 # 39
Where should raised-floor installation start?
- A. Point C (center of the room)
- B. Point A (entrance corner)
- C. Point B (side wall)
- D. Point D (corner opposite entrance)
正解：A
解説：
Best practice is to begin raised-floor installation at the center of the room, working outward. This minimizes alignment errors and ensures the tile grid is centered, which is critical for aisle containment and rack alignment.
Starting at the perimeter (A, B, D) causes cutting of tiles along both sides, misalignment with rack rows, and possible airflow inefficiencies. By starting at the center, tiles can be cut symmetrically around the edges, providing better aesthetics, balanced airflow, and structural stability.
Industry guidelines such as CISCA recommend this approach for raised floors in mission-critical spaces.
References: CISCA Raised Access Floor Guidelines, ANSI/TIA-942-B §6.3.
質問 # 40
What is the calculation for the desired attenuation factor for shielding material?
- A. A = 20 log (M / R)
Where
A is Attenuation
M is the maximum acceptable value
R is the real value measured - B. A is Attenuation
M is the maximum acceptable value
R is the real value measured - C. A = M / R
Where - D. A = 20 log (R / M)
Where
A is Attenuation
R is the real value measured
M is the maximum acceptable value - E. You do not have to calculate the attenuation factor for shielding material as it always has the same attenuation
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 # 41
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