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SK0-004 · Question #884

A server technician is procuring and installing a single-phase rack PDU that will meet the following requirements: Maximum line current per phase: 30A Rate current per phase: 24A Maximum current…

The correct answer is D. Purchase a PDU with a minimum load capacity of 5kVA. PDU load capacity is determined by multiplying the rated current per phase by the nominal voltage; the PDU selected must meet or exceed that value.

Server hardware installation and management

Question

A server technician is procuring and installing a single-phase rack PDU that will meet the following requirements:

Maximum line current per phase: 30A Rate current per phase: 24A Maximum current draw: 6 x 16A Nominal voltage: 208V Based on these requirements, which of the following can be implied regarding load capacity?

Options

  • APurchase a PDU with a minimum load capacity of 2kVA.
  • BPurchase a PDU with a minimum load capacity of 3kVA.
  • CPurchase a PDU with a minimum load capacity of 4kVA.
  • DPurchase a PDU with a minimum load capacity of 5kVA.

How the community answered

(17 responses)
  • A
    12% (2)
  • B
    6% (1)
  • C
    24% (4)
  • D
    59% (10)

Why each option

PDU load capacity is determined by multiplying the rated current per phase by the nominal voltage; the PDU selected must meet or exceed that value.

APurchase a PDU with a minimum load capacity of 2kVA.

2kVA equates to roughly 9.6A at 208V, far below the 24A rated current and dangerously undersized for this load.

BPurchase a PDU with a minimum load capacity of 3kVA.

3kVA equates to roughly 14.4A at 208V, still well below the 24A rated current requirement.

CPurchase a PDU with a minimum load capacity of 4kVA.

4kVA equates to roughly 19.2A at 208V, which does not meet the 24A rated current and would overload the PDU under normal sustained use.

DPurchase a PDU with a minimum load capacity of 5kVA.Correct

Using the rated current per phase of 24A at the nominal voltage of 208V gives 24 x 208 = 4,992 VA, which requires a PDU rated for at least 5kVA. The rated current (not the maximum line current) is used because it represents the sustained safe operating load the PDU must support. A 5kVA PDU is the minimum that covers the 4,992 VA load requirement.

Concept tested: PDU load capacity calculation using rated current and voltage

Source: https://www.schneider-electric.com/en/work/products/product-launch/power-distribution/

Topics

#PDU#power calculation#kVA#rack power

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