Planning to setup utility UPS systems.

[samalex]

Hi I am working as a graphic designer. In my shop I have my computers and it's related devices. among this some devices consuming more power. So if I am installing utility UPS systems in my office what kind of criteria should I follow. Will it help me to save over consumption of power?

 

[ads-ee]

"Over consumption of power", what is that supposed to mean?

The link you gave is to a power conditioner, it's mainly used to isolate you from your local power utility service. It also allows you to fail over to a local generator (which stays isolated from the utility) if utility power fails.

If anything it won't save you power and will likely make you use more utility power as such isolation systems will have power loss.

 

[D.A.(Tony)Stewart]

UPS requires battery charge and storage for DC-AC inverter to provide power when grid power is interrupted. These are called 2 stage UPS. A good design avoids power interruption, glitches and brown-outs that may drop your PC PSU , "faster than a rock", since they are designed cheaply to have only 1 cycle of storage capacity at line speed, unless under-utilized. ( So a good PC PSU is also important)

If the line is marginal to begin with, it can interrupt even faster unless it has an active PFC with regulated storage power independent of line input within the operating range.

More power hungry but in theory more reliable are 2 stage SMPS's that run off battery all the time meaning the 80% or so typ. efficiency of 2 stages (90%x90%) are always active so a fast transfer regulated AC out is not needed. THe batter charger only covers what power you use plus inherent no load losses for 2 stages (AC-DC and DC-AC)

Cheapo UPS systems output pseudo sine (3 level) or square wave(2 level) AC voltage and this increases stress on PC PSU caps and diodes reducing their life. Pure sine wave UPS systems are expensive, but then PC PSU's are cheap giving the obvious tradeoff of cost vs reliability. Having spare PSU'ss for PC's may be a good tradeoff or even a spare PC. Any redundancy is good.


Most important is warranty and guarantee.
then reliability and then cost of unit.
then the cost is dependant on your actual load power and storage power of UPS run time.
How long and how often do you lose power? Minutes? hourss? yearly? daily?

Cost of inefficiency may not be a top priority here but maybe there,
Let's use imaginary currency#

Let's say your electricity cost is 1#/kWh average.

Next assume you need 1 kilowatt (1kW) to run two small towers, 2 LCD's , a laptop laser printer etc
( it may be 2kW average and laser printers peak power may be 20x idle power during the heat cycle, so read specs or measure it.)

Then how much does it cost to waste UPS power assuming 5000h/year * 1kW * 100# (5kh= 13.7h/day x365)
Well that depends on efficiency. Let's say inefficiency is 20%.
then Load cost is 5kh * 1kW *1#/kWh = 5k# per year.
then UPS extra power is %loss x above.

Keep in mind a PC with a 500W PSU might only actually use 150W most of the time but more on demand
So a good AC power meter to measure actual device load may help size your battery or run-time calculations.
Then expect battery replacement every ~5 yrs or less.


Our power is up 99.999% of the time here in Toronto and shuts down up to minutes maybe a couple times a year and maybe few for a second.

So your needs may be different.

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https://www.smps.us/uninterruptible-power-supply.html

SPS inverter operates in standby mode and starts up only when the input source fails, it has the highest efficiency (95-98%) and reliability. Because it is also the cheapest UPS power supply (under $0.10 per rated volt-amp), it became the most common backup product used for desktop PCs. Note, in some older systems the inverter generated square-wave type output rather than a sinusoidal one, which could cause problems to some sensitive equipment.

This is probably the best bet for you. It may be interrupted but then only for as long as it takes to reboot and redo what you lost in work..

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Your biggest cost for long power interruptions is battery cost.

A typical 1500VA UPS gives you 1.6 minutes of interruption time with 17VAh car battery.

If you need a few hours you need to measure the VA load you have and determine the fast discharge capacity of the batteries you add to the unit.
https://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=7370379&csid=_61


So in your case if it is a long time, the biggest cost is battery and replacing them in 3 to 10 yrs depending on quality and cycles used.

The best solution depends on your specified requirements for VA and h ( total power and time)

It is rated in VA since many loads like PSU's are not PF corrected otherwise it would be watts.,

1st define your peak load with a power meter and include surge start power peaks
Test with a non-sine UPS and with grid power as it may be different results.

2nd define your average load in VA and W to determine the inverter size
3rd define the max energy storage required in VAh

Go shopping

Then when you need to decide how much to spend.
Estimate cost of power down time and lost work.
Compare with total cost of ownership for uninterrupted power over 10yrs.