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EXIN CDCS Exam Syllabus Topics:
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NEW QUESTION # 48
A data center requires an audit for ANSI/TIA-942 Rated-3 compliance. Will the network architecture be part of this audit?
- A. Yes, amongst other aspects the network architecture should be Rated-3 compliant with ANSI/TIA-942
- B. No, as concurrent maintainability only applies to electrical and mechanical
- C. No, only the type of cabling used will be audited
- D. Yes, but only if network administration does not comply with ANSI/TIA-606
Answer: A
Explanation:
ANSI/TIA-942 defines ratings across four areas:
* Architectural
* Electrical
* Mechanical
* Telecommunications (network cabling + architecture)
A data center cannot be considered Rated-3 unless all four areas meet the concurrent maintainability criteria.
For telecom/networking, this means dual redundant backbone cabling, proper pathways, and separate routes to ensure no single point of failure.
* A and B are incorrect because they limit scope to electrical/mechanical or cabling only.
* C is incomplete: administration (ANSI/TIA-606) is part of compliance but architecture redundancy is mandatory.
References: ANSI/TIA-942-B §5.2 (Rated Levels), Annex E (Telecommunications infrastructure examples).
NEW QUESTION # 49
The electrical diagram of the data center shows the following UPS configuration and has a load of 80 kW.
What is the set-up in this data center?
- A. N+N(+1)
- B. 2(N+1)
- C. (N+1)-(N+1)
- D. 2+N+1
Answer: B
Explanation:
A 2(N+1) configuration implies two independent UPS systems, each with N+1 redundancy. This configuration provides high availability by ensuring that each UPS system can independently support the load with an additional unit for redundancy. Given the 80 kW load, this setup implies that two separate N+1 systems are running, providing reliability and fault tolerance for the data center's power needs.
Detailed Explanation:
The N+1 notation denotes that each system has one additional unit beyond what is needed to carry the load, providing redundancy. With 2(N+1), there are two such setups, ensuring that if one fails, the other can still support the load without interruption, fulfilling high availability requirements.
EPI Data Center Specialist References:
EPI teaches that multiple redundant systems, such as 2(N+1), enhance data center reliability by ensuring that power is maintained even if a failure occurs in one system. This meets the stringent demands for uptime in critical environments.
NEW QUESTION # 50
Management has requested a 15-minute battery bank assuming full load on the UPS. The UPS vendor has provided the following specifications of the UPS:
*Rated power: 30 kVA
*Rectifier input voltage: 400 V/3 phase
*Rectifier input power factor: 0.8
*Battery rated voltage: 384 V
*Number of cells: 192
*End of discharge voltage: 308 V
*Inverter output voltage: 400 V/3 phase
*Inverter output power factor: 0.8
What information is missing to perform the battery calculation?
- A. Inverter efficiency
- B. UPS efficiency
- C. Load imbalance on the phases
- D. Available battery charging current
Answer: B
Explanation:
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: the UPS 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. The UPS efficiency affects 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 the UPS efficiency is 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.
NEW QUESTION # 51
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 increase the air volume by approximately 10%
- C. Dampers allow for a higher supply air temperature
- D. Dampers reduce the air volume by approximately 10%
Answer: D
Explanation:
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).
NEW QUESTION # 52
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. Nothing, the UPS will be able to take care of the right levels of THDi
- B. Install a passive harmonic filter on the UPS
- C. Install an isolation transformer rated at K13 or K20
- D. Install an active harmonic filter on the UPS
Answer: D
Explanation:
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.
NEW QUESTION # 53
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. Relative humidity has no influence on ESD
- B. ESD levels will go down
- C. No influence as long as the temperature is at approximately 20°C/77°F
- D. ESD levels will go up
Answer: D
Explanation:
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.
NEW QUESTION # 54
The building requires sprinklers and is equipped with a wet-pipe system. What action should you recommend for the computer room?
- A. Replace the wet-pipe system with a deluge system
- B. Replace the wet-pipe system with a pre-action system
- C. Replace the wet-pipe system with a dry-pipe system
- D. Maintain the current wet-pipe system
Answer: B
Explanation:
NFPA 75 (IT equipment rooms) recommends pre-action sprinklers for data processing spaces to minimize accidental water discharge risk; wet-pipe is generally discouraged directly over IT hardware.
References: NFPA 75 §5.4 (Water-based fire protection), NFPA 13 (sprinkler system types).
NEW QUESTION # 55
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. Install air-scrubbers.
- D. Clean the room and racks with a damp/wet cloth.
Answer: C
Explanation:
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.
NEW QUESTION # 56
You are allowed to use a calculator for this question.
A computer room has a net volume of approximately 2,500 m³ / 88,287 ft³.
The temperature is 20 °C / 68 °F.
The required design concentration is 7%.
The S-Factor is 0.1359 (metric) / 1.885 (imperial).
Calculate the amount of gas required for this computer room based on FM200. What is the correct weight?
- A. Approximately 410 kg / 900 lbs
- B. Approximately 1,390 kg / 3,000 lbs
- C. Approximately 1,640 kg / 3,600 lbs
- D. Approximately 820 kg / 1,800 lbs
Answer: D
Explanation:
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 approximately 1,800 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.
NEW QUESTION # 57
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 latent heat to the total of sensible plus latent heat to be removed from a conditioned space
- C. Ratio of the cold-aisle temperature to the hot-aisle temperature
- D. Ratio of cold-air supply to hot-air return temperature of a cooling system
Answer: A
Explanation:
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.
NEW QUESTION # 58
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. 12 Amperes
- B. 30 Amperes
- C. 80 Amperes
- D. 60 Amperes
Answer: B
Explanation:
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.
NEW QUESTION # 59
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. Nothing, the UPS will be able to take care of the right levels of THDi
- B. Install a passive harmonic filter on the UPS
- C. Install an isolation transformer rated at K13 or K20
- D. Install an active harmonic filter on the UPS
Answer: D
Explanation:
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.
NEW QUESTION # 60
What should be implemented when an Inergen-based fire suppression system is installed in the computer room?
- A. Pressure release valves in the data center
- B. Proper water leak detection system
- C. Gas tanks need to be within or close to the data center
- D. Drainage system under raised floor
Answer: A
Explanation:
Inert gas systems (Inergen, Argonite, Nitrogen) extinguish fires by reducing oxygen concentration through massive gas discharge. This rapid release causes a significant pressure rise inside the room. To avoid structural damage to walls, ceilings, or raised floors, pressure relief vents (pressure release valves) must be installed.
* A (drainage) applies to water suppression.
* B (tank location) is logistical but not mandatory; remote storage with piping is acceptable.
* D (water leak detection) is unrelated to inert gas suppression.
Therefore, the critical safety requirement is pressure relief.
References: NFPA 2001 §5.2.1.2 (Pressure Relief), ISO 14520-1 §5.2.
NEW QUESTION # 61
What is the redundancy setup shown in the diagram?
- A. 2(N+1)
- B. N+2
- C. 2+N+1
- D. N+N+N
Answer: B
Explanation:
The diagram shows three UPS modules, each 100 kW, connected in parallel to support a 100 kW IT load.
That means:
* One module (100 kW) can support the load (N).
* Two additional modules are installed as redundancy.
This equals N+2 redundancy.
* 2+N+1 and 2(N+1) imply dual active paths not shown.
* N+N+N is not an industry term.
Thus, the correct redundancy level is N+2.
References: ANSI/TIA-942-B §6.2 (UPS Redundancy Models), IEC 62040-3.
NEW QUESTION # 62
What is the first step in the design stage of the data center life cycle?
- A. Define the scope of the project
- B. Do a design validation
- C. Select vendors
- D. Freeze the design
Answer: A
Explanation:
The life cycle begins with planning and design. The very first step is to clearly define the project scope:
business requirements, capacity, availability targets, compliance standards, and budget. Without scope definition, design validation or vendor selection would be premature.
* Vendor selection (A) happens much later during procurement.
* Validation (B) occurs after conceptual and detailed designs are prepared.
* Freezing design (D) is the final stage before implementation.
Therefore, defining the project scope is the correct initial step.
References: ANSI/TIA-942-B Annex F (Lifecycle), ISO/IEC 30182 (Smart City & DC Lifecycle), PMI PMBOK (Scope Definition).
NEW QUESTION # 63
You are allowed to use a calculator for this question.
A computer room has a net volume of approximately 2,500 m³ / 88,287 ft³.
The temperature is 20 °C / 68 °F.
The required design concentration is 7%.
The S-Factor is 0.1359 (metric) / 1.885 (imperial).
Calculate the amount of gas required for this computer room based on FM200. What is the correct weight?
- A. Approximately 410 kg / 900 lbs
- B. Approximately 1,390 kg / 3,000 lbs
- C. Approximately 1,640 kg / 3,600 lbs
- D. Approximately 820 kg / 1,800 lbs
Answer: D
Explanation:
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}2,500 m3×0.07×0.1359=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 approximately 1,800 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.
NEW QUESTION # 64
ICT rack consumes 3 kW with #T ~11 °C (20 °F). Calculate required airflow (CFM).
- A. ~1,000 CFM
- B. ~160 CFM
- C. ~1,500 CFM
- D. ~500 CFM
Answer: D
Explanation:
Cooling airflow (CFM) can be calculated from:
Where P = IT load.
So approximately 500 CFM is required.
* 1,500 and 1,000 CFM are too high.
* 160 CFM is far too low.
Therefore, the correct answer is ~500 CFM.
References: ASHRAE TC 9.9 (Cooling Calculations), ANSI/TIA-942-B §6.5.
NEW QUESTION # 65
EMF shielding material needs to be installed as EMF levels from the transformer room into the computer room are measured at 100 mG. The transformer room is ~10 meters away, separated by a corridor. Where should shielding be installed?
- A. As close as possible to the computer room
- B. As close as possible to the transformer room
- C. It does not matter; either close to the transformer room or computer room is okay
- D. Shielding is not required as 100 mG is within acceptable levels
Answer: B
Explanation:
The most effective EMF mitigation is to install shielding as close as possible to the source of radiation. By blocking or redirecting magnetic flux at the origin (the transformer room walls), the overall field propagation into adjacent areas is minimized. If shielding were placed at the computer room, the field would already have spread over the intervening space, requiring more material and higher cost.
Standards such as IEEE Std 299 (EMC Shielding Effectiveness) and IEC 61000 emphasize source-based mitigation. Additionally, ANSI/TIA-942 requires EMF shielding where magnetic flux exceeds recommended ICT thresholds (generally <5 mG for sensitive tape/disk storage).
Although 100 mG is often tolerated by modern equipment, legacy magnetic storage can be affected, so shielding is still prudent. Hence, the correct location is at the transformer room wall.
References: IEEE Std 299 (EMI Shielding), ANSI/TIA-942-B §6.6.4 (EMF Requirements), IEC 61000 EMC standards.
NEW QUESTION # 66
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