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Exin CDCS Exam - Topic 1 Question 29 Discussion

Which class of UPS is ideal for data centers?
C) VFI (Voltage and Frequency Independent)
A) VFD (Voltage and Frequency Dependent)
B) VI (Voltage Independent)
D) First class

Exin CDCS Exam - Topic 1 Question 29 Discussion

Actual exam question for Exin's CDCS exam
Question #: 29
Topic #: 1
[All CDCS Questions]

Which class of UPS is ideal for data centers?

Show Suggested Answer Hide Answer
Suggested Answer: C

IEC 62040 defines UPS topologies:

VFD: Line-interactive; dependent on mains.

VI: Stabilizes voltage but not frequency.

VFI: Double-conversion online; fully isolates output from mains fluctuations.

Data centers require continuous, clean, and stable power. VFI is the only topology that protects against both voltage and frequency disturbances, meeting ANSI/TIA-942 Rated-3/4 requirements.

Thus, VFI is the ideal UPS class.


by Sanda at May 12, 2026, 08:35 AM

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Lenna
5 hours ago
I think VFI is the best choice. It offers stable power.
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Lon
5 days ago
Surprised to see VFD even mentioned here!
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Sheridan
11 days ago
Wait, is VFD really that bad?
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Adrianna
16 days ago
Definitely VFI, it handles fluctuations well.
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Edmond
21 days ago
I thought VI was more efficient?
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Geraldine
26 days ago
VFI is the best choice for data centers!
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Muriel
1 month ago
Totally agree, VFI is the way to go!
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Jeannetta
1 month ago
Wait, I didn’t know VFI was the top pick!
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Sarah
1 month ago
VFD? No way, that’s outdated!
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Lashandra
2 months ago
I thought VI was sufficient for most setups?
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Shelba
2 months ago
Definitely VFI is the best choice for data centers.
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Flo
2 months ago
I believe VFI is ideal because it provides the best protection against power issues, but I should double-check the definitions to be certain.
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Jutta
2 months ago
I’m a bit confused about the differences between VFD and VFI. I feel like I need to review their characteristics again.
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Nobuko
2 months ago
I remember practicing a question like this, and I think VFI was highlighted as the most reliable option for critical loads.
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Stephaine
4 months ago
I think the VFI class is the best choice for data centers, but I’m not entirely sure why it’s preferred over the others.
upvoted 0 times
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