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
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 Reference:
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.
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?
D
Explanation:
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 Reference:
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.
You need to determine the strategy for the cooling audit. All the servers are based on a front-to-rear
(F-R) airflow design.
Which location for the temperature/humidity measurement should you recommend for the audit?
C
Explanation:
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 a
front-to-rear (F-R) airflow design, measuring at the front/intake of the server will 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 humidity 50 mm/2
inches 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 Reference:
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.
You are installing new copper cabling.
What is the advantage or disadvantage of choosing pre-terminated category 6 or 6A cabling?
A
Explanation:
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 Reference:
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.
When are the wet bulb and dry bulb temperatures identical?
D
Explanation:
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 Reference:
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.
A new network storage device in a non-standard size rack of approximately 600 kg/1,300 lbs is going
to be installed in the data center.
Are new floor loading calculations required?
D
Explanation:
For heavy equipment, such as a network storage device weighing approximately 600 kg/1,300 lbs,
new floor loading calculations are indeed required, particularly since the rack is non-standard. A
structural engineer, approved by the building owner, should conduct these calculations to ensure the
floor can safely support the new load without risking structural integrity.
Detailed Explanation:
Data centers are designed with specific floor load ratings, which are determined during the design
phase based on anticipated equipment. When adding or replacing equipment that is significantly
heavy or non-standard, reassessing the floor's capacity is essential to avoid overloading. A structural
engineer has the expertise to verify if the existing floor can accommodate the weight and, if not, can
recommend reinforcement measures.
This step ensures compliance with safety standards and helps prevent damage to the infrastructure,
which could lead to costly repairs or even catastrophic failure in extreme cases.
EPI Data Center Specialist Reference:
EPI Data Center Specialist training advises that any changes in the data center load, particularly
involving non-standard and heavy equipment, warrant a structural assessment. Ensuring compliance
with floor load capacity is a critical safety and operational concern, as underscoring data center
infrastructure reliability and safety is a priority in EPI's best practices.
A data center has its own power supply from the public utility and receives chilled water supply from
the building owner.
What needs to be taken into consideration when calculating the PUE?
C
Explanation:
When calculating Power Usage Effectiveness (PUE) in a data center that uses chilled water from an
external source, like from a building owner, a weight factor for district chilled water must be applied.
This is because PUE calculations aim to measure the energy efficiency of the data center’s own
operations, and external utilities like district chilled water aren’t directly powered by the data center.
A weight factor of 0.4 is typically used to account for the energy consumed to produce and deliver
the chilled water, reflecting the indirect impact on the data center’s total energy consumption.
Detailed Explanation:
PUE is calculated as the ratio of the total facility energy to the IT equipment energy. If the cooling is
provided by an external chilled water source, it’s necessary to adjust the calculations to accurately
reflect the energy impact. By incorporating the 0.4 weight factor, data centers can calculate a more
accurate PUE, aligning with standard methods and industry best practices.
EPI Data Center Specialist Reference:
EPI training on PUE highlights the importance of adjusting for external energy sources, such as
district cooling, in the calculations. This ensures that PUE values remain accurate and comparable
across different data centers, even when external utilities are used.
What is the main reason to install Earth Leakage protection?
B
Explanation:
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 Reference:
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.
The noise levels in the data center are approximately 91 dB (A).
Do employers need to take precautions?
D
Explanation:
In a data center with noise levels of 91 dB (A), employers are indeed required to take precautions to
protect personnel, as this level exceeds commonly accepted safety thresholds for occupational noise
exposure. Regulations, such as those from the Occupational Safety and Health Administration (OSHA)
or similar agencies, mandate specific controls and protections for environments with high noise
levels.
Detailed Explanation:
Noise levels above 85 dB (A) typically trigger requirements for hearing conservation programs. At 91
dB (A), steps like providing ear protection, conducting regular noise assessments, and possibly
implementing engineering controls to reduce noise should be taken. Extended exposure to such
levels can lead to hearing loss, so regulatory compliance ensures both immediate and long-term
protection for personnel.
EPI Data Center Specialist Reference:
EPI guidelines for data center safety address noise exposure as part of the environmental safety
measures. EPI recommends adhering to local occupational health regulations, as excessive noise can
harm personnel and affect operational efficiency due to potential health hazards.
The UPS of a data center, with an ANSI/TIA-942 Rating-4, is installed with the rectifier connected to
power feed A and the bypass/reserve line input connected to power feed B.
To which feed will the output of the UPS be synchronized?
B
Explanation:
For a UPS system in a Rating-4 data center, the synchronization of output can indeed depend on the
specific settings of the UPS. Generally, such systems allow for flexible configuration where the output
can be synchronized to either power feed A or B, depending on which feed is preferred for stability or
redundancy purposes.
Detailed Explanation:
In dual-feed setups, such as those in high-redundancy data centers, the UPS can be set to
synchronize with either feed. This ensures that the UPS maintains continuity in case one feed
becomes unstable or fails. The flexibility to choose synchronization to either feed enhances the
resiliency and reliability of power supply, which is critical in Tier IV (Rating-4) facilities where uptime
is paramount.
EPI Data Center Specialist Reference:
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.
What is a potential disadvantage of using a hypoxic-based fire suppression system as a fire
extinguishing system?
C
Explanation:
A hypoxic-based fire suppression system works by reducing the oxygen level in a room to below what
is necessary to sustain combustion. This makes it effective in fire prevention, but it is not suitable for
continuous occupancy by personnel. Low oxygen levels can cause discomfort or even health risks for
people spending extended periods in the space. Therefore, these systems are typically deployed in
areas where continuous human occupancy is not required, such as storage rooms or data halls with
limited personnel access.
Detailed Explanation:
Hypoxic fire suppression systems lower oxygen levels to around 15-16%, which is safe for short
periods but not sustainable for continuous occupancy without risk to health. Data center
environments where staff need to spend long periods monitoring and maintaining equipment would
need alternative systems, like gas-based suppression that allows for safe evacuation rather than
oxygen reduction.
EPI Data Center Specialist Reference:
The EPI Data Center Specialist curriculum emphasizes that fire suppression systems must be chosen
based on occupancy requirements. Hypoxic systems are specifically noted as unsuitable for spaces
requiring continuous human presence due to the low oxygen environment they create.
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)?
C
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 Reference:
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.
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
Explanation:
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 Reference:
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.
A computer room needs to be fitted out with a gas-based fire suppression system. The computer
room will be a high-density data center with about 30% of the racks being closed circuit cooling
blade-center racks.
Should the supplier of the fire suppression system be informed on the design of the racks?
C
Explanation:
The design and configuration of racks, particularly high-density and closed-circuit cooling racks,
directly impact the fire suppression system design. Closed-circuit cooling racks, like blade-center
racks, can affect airflow and potentially trap heat, influencing how fire suppression agents are
distributed within the space. Therefore, it is essential to inform the fire suppression system supplier
about the rack design to ensure effective coverage and proper agent distribution.
Detailed Explanation:
High-density racks can change how smoke and heat travel, which in turn affects fire detection and
suppression. Closed racks with built-in cooling can isolate airflow, requiring adjustments in fire
suppression design to ensure that suppression agents reach all necessary areas, including within
enclosed spaces. The supplier may need to account for these factors to ensure proper protection
coverage.
EPI Data Center Specialist Reference:
The EPI Data Center Specialist training underscores that fire suppression systems must be tailored to
the specific environmental characteristics of the data center. The design of racks, particularly high-
density configurations, should always be considered to ensure that suppression agents can
effectively control a fire, even in contained rack spaces.
The 'maximum exposed area' of the fire-rated glass is defined by the supplier as 3 sqm/32 sqft. The
window area is 4 sqm/43 sqft.
What would be the best option?
C
Explanation:
When the window area exceeds the maximum exposed area specified for fire-rated glass, it is
necessary to split the window into sections that comply with the fire rating requirements. This means
creating smaller sections that are each within the 3 sqm/32 sqft limit and using fire-rated frames to
ensure that the entire assembly meets fire safety standards. This approach maintains the fire-rated
integrity of the glass, while allowing for larger window areas.
Detailed Explanation:
Fire-rated glass is designed to contain fire and prevent it from spreading. If the window exceeds the
maximum exposed area defined by the supplier, the integrity of the fire-rated glass could be
compromised. By dividing the window into compliant sections with fire-rated frames, you ensure
that each pane performs as intended in the event of a fire. Fire-rated frames help maintain the fire
resistance across the entire assembly, making this option the best for safety and compliance.
EPI Data Center Specialist Reference:
EPI recommends adhering strictly to fire safety standards, especially when using materials like fire-
rated glass. The guidelines emphasize that modifications should always respect the manufacturer’s
specifications to ensure the system remains effective in containing and preventing the spread of fire.