UPS power must be higher than PSU rated power?

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Discussion Overview

The discussion revolves around the relationship between the rated power of a Power Supply Unit (PSU) and the required power rating for an Uninterruptible Power Supply (UPS). Participants explore whether the UPS must exceed the PSU's rated power and by how much, considering different load scenarios and assumptions about power consumption.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • Some participants question if the PSU's marked power (e.g., 1000W) represents output power and suggest that the UPS must be rated higher than this value.
  • Others argue that the actual load drawn from the PSU may be significantly lower than its maximum rating, proposing that a UPS rated about 20% higher than the actual load would suffice.
  • One participant shares a personal example of using a 600W PSU with a peak consumption of 150W, suggesting that a smaller UPS could be adequate if the peak consumption is measured.
  • There is a discussion about the importance of measuring peak consumption before selecting a UPS, with some suggesting that a UPS should be rated higher than the maximum output of the PSU.
  • Questions arise regarding the input power specifications of the UPS and whether they are relevant to the discussion about PSU ratings.
  • Several participants express confusion about the definitions of input and output power in the context of UPS and PSU, leading to clarifications and misinterpretations of the original question.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the exact power rating required for the UPS in relation to the PSU. There are multiple competing views regarding how much higher the UPS should be rated compared to the PSU, and the discussion remains unresolved.

Contextual Notes

Some limitations include the lack of specific assumptions about load conditions, the need for clarity on definitions of input and output power, and the varying interpretations of PSU ratings among participants.

user079622
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Is PSU marked power, output power?
If PSU has marked 1000W that mean it drain /input power is higher than 1000W so UPS must be higher than 1000W(PSU rated power)?
How much higher UPS power must be, assumption is that ups drive only computer and monitor(maybe only 20W)?
 
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The PSU may be able to source 1000 watt, but the load may only be drawing a maximum of 500 watt.
The UPS would need to be rated something like 20% more than is needed, about 600 watt to support that 500 watt load on the PSU.
 
user079622 said:
Is PSU marked power, output power?
The datasheet should show both input requirements and output capability.
 
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Baluncore said:
The PSU may be able to source 1000 watt, but the load may only be drawing a maximum of 500 watt.
The UPS would need to be rated something like 20% more than is needed, about 600 watt to support that 500 watt load on the PSU.
More than is needed or rated?
If psu has rated 1000w, ups must be 1200w?
 
user079622 said:
More than is needed or rated?
More than is going to be needed.
 
user079622 said:
If PSU has marked 1000W that mean it drain /input power is higher than 1000W so UPS must be higher than 1000W(PSU rated power)?
It's advisable to measure the peak consumption of the set before selecting an UPS.

For example I have a rig with a 600W PSU (recommended due the VGA card).
It eats up around 60W average/idle (with monitor).
The peak is around 150W.

In theory I could do with a 300W UPS (with ~ a dozen minutes of uptime, worst case) but since I wanted long battery time (even at the end of the battery lifetime) I bought a 900W one - that was the type with the biggest single battery I could fetch.
 
Baluncore said:
More than is going to be needed.
@berkeman

At psu write max total output is 1450W.
That mean it can drian 20% higer then that.
 
user079622 said:
At psu write max total output is 1450W.
And what voltage and current are listed at the power cord input to the UPS?
 
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berkeman said:
And what voltage and current are listed at the power cord input to the UPS?
I dont know.
Why do you need power input of UPS?
 
  • #10
user079622 said:
I dont know.
Just look where the power cord goes into the UPS...

user079622 said:
Why do you need power input of UPS?
I guess I don't at the start of this thread, you were asking whether the "power" of a UPS was its input or output power.
 
  • #11
berkeman said:
Just look where the power cord goes into the UPS...I guess I don't at the start of this thread, you were asking whether the "power" of a UPS was its input or output power.
I dont have UPS and I didnt ask that.
I ask for PSU power..
 
  • #12
user079622 said:
Is PSU marked power, output power?
If PSU has marked 1000W that mean it drain /input power is higher than 1000W so UPS must be higher than 1000W(PSU rated power)?
How much higher UPS power must be, assumption is that ups drive only computer and monitor(maybe only 20W)?
Okay, I guess I misinterpreted your OP. Nevermind.
 

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