English Community

Datacenter SystemsThinkSystem
All Forum Topics

1 Posts



4 Signins

10 Page Views

  • Posts: 1
  • Registered: ‎07-08-2020
  • Location: US
  • Views: 10
  • Message 1 of 2

ST550 with redundant 750's UPS Power Requirement

2020-07-08, 18:44 PM

In trying to size the UPS and runtime requirements of an ST550 with redundant 750w power supplies, what is the reasonable power requirement to budget for on a UPS?


413 Posts



1968 Signins

30023 Page Views

  • Posts: 413
  • Registered: ‎03-07-2017
  • Location: TW
  • Views: 30023
  • Message 2 of 2

Re:ST550 with redundant 750's UPS Power Requirement

2020-07-10, 2:26 AM

Hi NormL


Provide you with a rough calculation for your reference:


1.List all equipment to be protected by the UPS. 

In this case, only ST550.


2.List the amps and volts for each device.  Multiply amps by volts to determine VoltAmps (VA).  

Assume that this ST550 has two 750w PDUs(redundant). According to the formula to convert the Watts to Volt Amps: W = VA * pf ( For servers, the power factor is often 0.9)

In this case, the VA of each PDU is 750/0.9


3.Multiply the VA by the number of pieces of equipment to get the VA subtotals.

Two PDUs VA= (750/0.9)*2 = 1667


4.Add the VA subtotals together.


5.Multiply the total by 1.2 to get the grand total. This step ensures the redundancy.

1667*1.2 = 2000


6.Use the grand total to select a UPS. When choosing a UPS, be sure that the total VA requirement of supported equipment does not exceed the VA rating of the UPS.


Please feel free to leave your comment, thank you for support Lenovo
Forum Home

Community Guidelines

Please review our Guidelines before posting.

Learn More

Check out current deals!

Go Shop





No, I don’t want to share ideas Yes, I agree to these terms