Sinewave and non sinewave in UPS

[blackblack1]

I have an APFC PSU (Corsair CS650M). Some said that APFC PSU need pure sinewave AC for it to run smoothly. Unfortunately I have an offline UPS that generate synthesized sinewave (non-sinewave).

I need to confirm one thing, does the offline UPS generate non-sinewave only when in battery mode, and generate sinewave whenever it plug into direct AC power, or am I missing something ?

Thanks a lot.

 

[Karsten75]

I have an APFC PSU (Corsair CS650M). Some said that APFC PSU need pure sinewave AC for it to run smoothly. Unfortunately I have an offline UPS that generate synthesized sinewave (non-sinewave).

I need to confirm one thing, does the offline UPS generate non-sinewave only when in battery mode, and generate sinewave whenever it plug into direct AC power, or am I missing something ?

Thanks a lot.

If you don't provide make/model of your "offline UPS", how do you expect us to divine how it works?

 

[blackblack1]

If you don't provide make/model of your "offline UPS", how do you expect us to divine how it works?

I'm sorry, didn't realize I forgot to mention that. The model is ICA CP1400.

 

[Karsten75]

OK that seems to be a line-Interactive system

Line Interactive UPS

In the line interactive design, the battery and AC power inverter are perpetually connected to the UPS output, and the battery can be charged by operating the inverter in reverse while AC power is set at normal levels. In case of power failure, the transfer switch can shift electrical flow from the battery to the system output. Because the inverter is continuously connected to the output, the UPS provides additional filtering and lowers the risk of switching transients. A tap-changing transformer is sometimes included in the line interactive UPS, and this allows it to provide voltage regulation that prevents the UPS from switching to battery power prematurely. The line interactive design’s high levels of efficiency and reliability, as well as its relatively small size and low cost, make it well-suited for a range of uninterruptible power applications.

http://www.thomasnet.com/articles/electrical-power-generation/ups-system-types

[strike]That seems to imply that the output current is supplied is always treated and hence will be simulated sine wave. I may be wrong, though. [/strike] Edited to correct better information provided later in thread.

Here is a good read of the two types of UPS device commonly available in low-power applications.

http://www.apcdistributors.com/white-papers/Power/WP-79%20Technical%20Comparison%20of%20On-line%20vs.%20Line-interactive%20UPS%20designs.pdf

 

[blackblack1]

OK that seems to be a line-Interactive system

Line Interactive UPS

In the line interactive design, the battery and AC power inverter are perpetually connected to the UPS output, and the battery can be charged by operating the inverter in reverse while AC power is set at normal levels. In case of power failure, the transfer switch can shift electrical flow from the battery to the system output. Because the inverter is continuously connected to the output, the UPS provides additional filtering and lowers the risk of switching transients. A tap-changing transformer is sometimes included in the line interactive UPS, and this allows it to provide voltage regulation that prevents the UPS from switching to battery power prematurely. The line interactive design’s high levels of efficiency and reliability, as well as its relatively small size and low cost, make it well-suited for a range of uninterruptible power applications.

http://www.thomasnet.com/articles/electrical-power-generation/ups-system-types

That seems to imply that the output current is supplied is always treated and hence will be simulated sine wave. I may be wrong, though.

Here is a good read of the two types of UPS device commonly available in low-power applications.

http://www.apcdistributors.com/white-papers/Power/WP-79%20Technical%20Comparison%20of%20On-line%20vs.%20Line-interactive%20UPS%20designs.pdf

Thank you very much !

After read the references you gave, my thought is that in usual condition (no power failure), the UPS is switching to AC power, not battery. In some websites of Line Interactive UPS brand, some manufacturers wrote that in AC mode, the waveform is sinewave, while in battery mode, the waveform is simulated sinewave.

(ex : http://www.prolink2u.com/newtemp/line-interactive-ups/260-pro1200sv-pro1200svu-pro1200-series.html)

Unfortunately ICA didn't write as detailed as that on their website thus making me curious about that

 

[ko888]

On a line interactive UPS the wave form is a sine wave when operating on the AC power grid since there is no power conversion going on.

When there is a power interruption event the UPS should switch over to battery backup mode that converts the battery's DC power into AC power through an inverter. The wave form, that the inverter creates, is a simulated sine wave which may be a problem with some PSUs that have an APFC circuit. If there is an incompatibility then the UPS will fail to switch over to battery backup mode or it will report an overload condition and shut itself down

 

[blackblack1]

On a line interactive UPS the wave form is a sine wave when operating on the AC power grid since there is no power conversion going on.

When there is a power interruption event the UPS should switch over to battery backup mode that converts the battery's DC power into AC power through an inverter. The wave form, that the inverter creates, is a simulated sine wave which may be a problem with some PSUs that have an APFC circuit. If there is an incompatibility then the UPS will fail to switch over to battery backup mode or it will report an overload condition and shut itself down

Thank you very much ! A clear explanation. Which one shut itself down first when incompatibility occur ? The UPS or PSU ?

 

[ko888]

On a line interactive UPS the wave form is a sine wave when operating on the AC power grid since there is no power conversion going on.

When there is a power interruption event the UPS should switch over to battery backup mode that converts the battery's DC power into AC power through an inverter. The wave form, that the inverter creates, is a simulated sine wave which may be a problem with some PSUs that have an APFC circuit. If there is an incompatibility then the UPS will fail to switch over to battery backup mode or it will report an overload condition and shut itself down

Thank you very much ! A clear explanation. Which one shut itself down first when incompatibility occur ? The UPS or PSU ?

The UPS will shut itself down when detects an overload condition. There may not be an actual overload condition but the UPS thinks there is one.

 

[blackblack1]

The UPS will shut itself down when detects an overload condition. There may not be an actual overload condition but the UPS thinks there is one.

Then the CPU will shut down incorrectly just like without UPS?

 

[ko888]

The UPS will shut itself down when detects an overload condition. There may not be an actual overload condition but the UPS thinks there is one.

Then the CPU will shut down incorrectly just like without UPS?

Exactly. If the UPS is unable to switch over to battery backup mode without any problem then it is essentially useless.

A pure sine wave UPS avoids any incompatibility problem.