CDCS Exam Dumps - Exin EPI Data Centre Questions and Answers

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.

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 References:

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.

EoR centralizes access/aggregation switches at the end of each row, reducing the number of access switches compared with ToR (one per rack), which simplifies management and often lowers Ops costs.

A, D are incorrect generalizations.

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.

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.

An air intake temperature of 25 °C (77 °F) at the top of the rack is acceptable according to data center standards and guidelines, such as those from ASHRAE. This temperature falls within the recommended range for inlet temperatures, which is typically between 18°C (64°F) and 27°C (81°F).

Detailed Explanation:

ASHRAE standards provide guidelines on acceptable temperature ranges for air intake in data centers to balance cooling efficiency and equipment safety. A temperature of 25°C is within the recommended operational range, allowing data centers to optimize energy efficiency while maintaining safe conditions for IT equipment.

EPI Data Center Specialist References:

EPI guidelines align with ASHRAE recommendations for server intake temperatures, confirming that 25°C is within acceptable limits for most mission-critical equipment. This ensures the data center maintains an efficient and reliable environment.

Commissioning occurs during the Implementation stage of the data center life cycle. This phase involves the final testing and verification of systems and equipment to ensure they meet design specifications and operational requirements before the data center goes live.

Detailed Explanation:

The Implement phase includes activities such as installation, configuration, and testing. Commissioning is a crucial step that validates the performance and reliability of all critical systems, including power, cooling, and network infrastructure, to ensure they operate as intended under various conditions. Proper commissioning helps identify and resolve any issues before the data center becomes fully operational.

EPI Data Center Specialist References:

EPI training emphasizes that commissioning is essential for verifying that the data center meets design and performance criteria, aligning with best practices in data center project management to minimize risks and ensure readiness for operation.

The minimum requirement for power feeds to a Rated-3 data center according to ANSI/TIA-942 is to have two independent power feeds, which can come from two different substations provided by the same power company. This ensures redundancy and concurrent maintainability, as each feed can support the load independently during maintenance or failure of the other.

Detailed Explanation:

The separation by two substations ensures resilience in case of a localized outage or substation maintenance, aligning with Rated-3 requirements for uninterrupted operation. ANSI/TIA-942 permits these feeds from a single utility provider as long as they are supplied from distinct substations.

EPI Data Center Specialist References:

EPI underscores the importance of dual power feeds from separate substations for Rated-3 facilities, highlighting that the ability to draw from different substations aligns with redundancy requirements for high availability.

The aisle pitch is the total width of a rack row plus cold aisle plus rack row. For 1.0 m racks on each side with cold aisle containment, ASHRAE and TIA-942 recommend the 7-tile rule (each tile ~0.6 m). This ensures enough width for equipment clearance, airflow distribution, and human access.

5-tile pitch is too narrow, restricting containment effectiveness.

8–10 tiles may be used in some hyperscale layouts but are not standard for 1 m racks.

Thus, the correct design recommendation is the 7 tiles pitch rule.

Testing smoke sensors should be conducted according to the vendor specifications to ensure compliance with safety standards and accurate results. Vendors provide specific testing procedures to account for the sensor type, environment, and operational characteristics, ensuring that tests do not damage the equipment or provide false results.

Detailed Explanation:

Smoke sensors can vary by type and sensitivity, so following the vendor's recommended testing procedure ensures the sensors function correctly without risking sensor damage. Injecting smoke or using a self-test might be insufficient or could lead to inaccurate assessments if they do not align with the vendor's testing protocol.

EPI Data Center Specialist References:

EPI recommends adhering to manufacturer specifications for testing critical safety equipment, ensuring that tests reflect real-world conditions without compromising sensor integrity or reliability.