480volt UPS Solutions

Last month we talked about people using their home's 240volt power to operate 208volt UPS systems.  In that case customers could choose a 240volt UPS or buy a buck transformer to lower voltage to 208v.

In the case of 277/480volt power, the problem is the same, the solution a bit different.

Taking the 277volt line and powering a 208volt UPS with it will cause the UPS to immediately start shedding the power.  Yes the specs say it can take 189-294volts, but it is not designed to do this continuously.

Option 1 is to transform the entire load from 3phase 277/480volt down to 120/208.   This is expensive and requires a 300lb transformer (assuming a 10kva ups).  With the transformer, freight, and electrical work, this can cost over $3000.

Our recommendation, is to use a buck transformer and step down from 277 to 240volt.  Since, you cant simply buck all the way down to 208volt, you need a 240volt UPS.   This smaller transformer fits in a 3U rack cabinet and costs under $400.   Call us for the exact price based on your size

Either way, these are much cheaper solutions than trying to buy a 480volt UPS.

Fun fact... go to the APC Selector by load and ask for a 5000va UPS with 277/480volt power, put in 10mins and 10% expansion... and the selector spits out a $99,600 UPS solution

There is no S.U.R.G.E in a UPS

Well actually, there is a little, but its not worth trusting your expensive IT equipment to it.

A cheap power strip selling for $7 offers nearly the same amount of surge arresting protection as the $1700 APC Smart UPS 3000va UPS.

versus




In the mickey mouse world of plug in surge suppressors, the strip has 770 joules and APC ups has 880 joules.  While you'll learn what all that means here, to me the main point is that whether you can trust your plug in strip for serious protection.  If you dont then why would trust your UPS for surge protection.

If you are like me, a surge strip is an extension cord, and i wouldn't trust for anything critical or expensive.

Your solution... buy a hardwired, panel mount surge suppressor.  We have good ones here at our store.

120volt versus 208volt

If you can have either, what should it be?

I always recommend 120volt. But....
Choose 208volt for dense server racks that need a lot of power. 208volt provides more Uumph per outlet. (U/o) The main disadvantages are that 208volt units are more money and not all computer equipment can run on 208volt .

However, APC disagrees. Their white paper makes an argument for increased efficiency by going to 208volt . While it is true that units draw less current (amps) when you increased voltage (from 120v to 208) and hence cause less heat... its a paltry amount.

I told a customer recently, that I bet him leaving the light on in the server room causes more heat loss than the savings from 208volt to 120v. I suspect I will get an email from someone shortly proving me wrong.

UPSes and Generators

This week, we have had lots of discussions with people needing a UPS in combination with a generator.

Many large companies used to buy very large UPS systems to survive power outages.  However, with the high costs and limtations of these room UPSes many are now looking for a more affordable way.

Now the thinking is have a UPS that offers just enough runtime, until the generator can be activated.

If you are thinking of this design, remember generators provide "dirty power" so be sure to have:

• surge suppression on your panel feeding your UPS
• consider UPS units which use the Double Conversion ups technology, insuring clean power.

Other nice tidbits for our experience wtith generators for Hurricane Wilma:

• keep surge strips & extension cables handy... to reconfigure loads or reroute UPSes as needed.
• buy a led strip light for your server room... every watt is precious during generator runs
• keep several small desktop upses around... as replacements or casual offline use
• triage your loads as "important" and bare bones "essential" and make sure PDUs and UPSes contain only those loads.
• install an blue colored outlet that is connected to generator system, but not to the UPS for things like box fans and charging station.

The Power of U

UPS units have a power handling and battery module.  In rackmount units, they combine these 2 modules into a various form factor or rackspace thickness, called U.
Most manufacturers make a 3000va unit in a 2U, 3U or 5U format.
While there is no difference* in a the power handling capacities of each form factor, there are big differences in the battery capacity.
A 3000va 2U UPS unit using 1500va like the SUA3000RM2U has a runtime of 10min.  A 3000va 5U UPS unit using 1500va like the SU3000RMNET has a runtime of 19min.
This difference is because of the size of battery capacity.
Remember, while we express POWER capacity in VAs, we express BATTERY capacity in VAhs.   And this battery capacity is limited by physical space of the form factor.
Notice the battery capacity of the various 3000 units.

• SUA3000RM2U - 480VAh  (10min)
• SU3000RM3U - 672VAh (15min)
• SU3000RMNET - 864VAh (19min)

So remember, while all 3000va units have the same power (in VAs), the battery capacity of each form factor varies.

Oh, I could have had a VA

VA, or volt-ampere is the unit of measurement used to describe UPSes. Wikipedia has a great definition for it.

"While the volt-ampere (abbreviated VA) and the watt are dimensionally equivalent one may find products rated in both VAs and watts with different numbers. This is common practice on UPSs (Uninterrupted Power Supplies). The VA rating is the apparent power that a UPS is capable of producing, while the watt rating is the real power (or true power) it is capable of producing, as opposed to reactive power"

Remember, VA is not the amount of runtime for the UPS.
VA is the capacity of the transformers for the UPS.
More VA means more things you can plug into the unit.

In other words, given the standard 3U 120volt UPS and a 500watt light bulb…
A 3000va UPS will not last any longer than the 2200va UPS.