Nominal Output Voltage

Nominal Output Voltage is the voltage that the UPS supplies to the connected equipment while on battery.  It should be matched with the input voltage of you load.

Voltage Requirements

The voltage requirement is the input requirement for the UPS.

It usually goes something like this: We have to upgrade our server. We probably should upgrade our whole setup to deal with the power requirements. Hmm… budget’s tight. We already have server racks, each with a single or multiple UPS units installed. Could we re-arrange the power distribution and save some cash? How would that work?  Please pass the aspirin…

The good news is that you might actually be able to – with the right understanding of power redundancy. Contrary to popular belief, this isn’t strictly limited to large infrastructure installments, and can also be easily incorporated into single server-rack installations. By rearranging your current equipment, you can unlock the full potential of your existing hardware, greatly increasing your up-time, and limiting the occurrence of a power failure interruption.

Why use redundancy in power distribution?

A UPS has a big job to do – ensure reliable power delivery and protect your equipment – and they do it well. Until, they don’t. UPS units, like everything else, need maintenance and with the popular (but not advised) “set ‘em and forget ‘em” mindset, they sometimes fail. So, there’s a good chance that at some point your equipment will be offline for a period of time.

With at least two power sources, a redundant system eliminates single point failures. In the event that one source should fail (or require routine maintenance), the second will ensure your equipment is still protected and supplied with reliable power.

Here’s the “how-to”:

Your Options: Basic Power distribution models

Capacity or “N” system (no redundancy)

An N system is a system comprised of a single UPS module, or a paralleled set of modules whose capacity is matched to the critical load projection. This type of system is by far the most common of the configurations in the UPS industry. The small UPS under an office desk is an N configuration, as per Figure 1.0.

Parallel “N+1” system (redundant system)

Parallel redundant configurations allow for the failure of a single UPS module without requiring that the critical load be transferred to the utility source. A parallel redundant configuration consists of paralleling multiple, same-size UPS modules onto a common output bus.

These configurations can include additional components to better improve single point failure elimination:

• Automatic transfer switches (ATS)
• Static transfer switches (STS)
• Power distribution units (PDU)
• External maintenance bypass switches
• Additional Battery packs

Examples:

• If your system draws 100W, and you install a single 100W UPS, this can be described as an “N” type configuration.
• If a system draws 100W, and two 100W UPS’s are installed in parallel operation, the configuration is considered an “N+1”.
• If the load is 100W, and there are three paralleled 100W UPS’s, the configuration would be “N+2” …and so on.

It isn’t uncommon to find expressions such as “2N”, “N-1”, “2(N+1)”, but they’re generally representations of larger power distribution schemes, or lesser commonly used denotations.

Redundant configurations

Single-Corded design

This design will offer protection for equipment with a single power supply or input.
Represented by arrows in Figure 2.0, the power cords from the equipment are connected to a Power Strip or PDU within the rack installation. The Power Strip is supplied directly from an ATS which is installed as an intermediary between the UPS’s and the Power Strip. In the event of scheduled maintenance or a single UPS failure, the ATS will automatically redirect 100% of the available power from the remaining UPS to the Power Strip.

Dual-Corded design

This design will offer protection for equipment with dual power supplies.
Represented by arrows in Figure 3.0, the power cords from the equipment are connected to two separate Power Strips or PDU’s. Redundancy in this system is achieved by dedicating a UPS to each Power Strip. Under normal operation, the equipment will draw 50% of its power requirements from Power Strip 1 and 50% from Power Strip 2. With the loss of UPS1, UPS2 will continue to supply Power Strip 2 and the equipment will redirect 100% of the required power draw through the remaining active power supply.

Greater redundancy

In the pursuit of eliminating single point failures, these pointers can greatly improve upon the redundancy of a power distribution system:

• Use modular UPS’s. These devices can be easily scaled-up to improve redundancy.
• Always pair a Power Module with Battery Module within a Modular UPS.
• Install additional External Battery Packs.
• Make backup Generator power accessible to your system through the implementation of a STS or ATS.

Feel free to reach out to us about your specific power needs. We love this stuff.

-Eddie

Additional resource:
- Comparing Availability of Various Rack Power Redundancy Configurations

When an updated alarm clock with Double A batteries is out of reach, just hook up a BE550G and you’ll always be up on time (courtesy of Rick’s mom):

*Long drive + two daughters + wife – iPhone/iPod/iPad = unbearable. A SU700 should do the trick (courtesy of Rick):

Fishes need power, too (courtesy of COO, Adam):

We take our coffee VERY seriously (courtesy of CBM break room):

Have one to add? We’d love to see it! Email us you’re pic, or post it to our Facebook page, and we’ll send you a CBM t-shirt (while supplies last).

*How the heck does this work? The UPS is charged and ready to go, then it’s plugged into a surge protector that’s plugged into a converter that’s then plugged into the car. And, yup, they’ve blown it out a few times.

Problem to solve?  Question to answer?  There’s probably a big, color-coded sticky note for that, either currently adorning our walls or in our files (i.e. big pile of folded notes on the floor of various offices).

One of our conference rooms.

So, when I started to write this post about Offline VS Online units, I knew exactly where to turn.  On one of my first days with the company, I was given a very comprehensive lesson complete with – you guessed it – a big sticky note.

Offline (bottom red) vs Online ( orange)

Before really digging into Offline VS Online, we should probably go over the 3 main parts of a UPS:

1. Rectifier: converts AC (wall power) to DC (battery voltage)
2. Batteries: reserved power
3. Inverter: inverts DC (battery power) to AC (wall power)

Now, let’s go over an offline unit.  In an offline unit (bottom red), most of the available power coming out of the wall goes directly to the computer (or other device the UPS is protecting), and some of the power goes through the rectifier and to the battery to keep the battery charged.  The inverter is normally off.  In the event of a power outage, the rectifier turns off and the inverter switches on to draw power from the battery to power to the load.  The switchover time is 4 milliseconds, which is acceptable in most circumstances.

The online unit (orange), on the other hand has no switchover time, because the UPS is always online.  In other words, all available power from the wall always go through the rectifier, charges the batteries, and then goes through the inverter to power the computer.  If the power goes out, the rectifier simply shuts off, the battery continue to supply power to the inverter and it’s business as usual.  Zero switchover time.

Besides switchover time, there are may pros and cons:

An offline unit is generally sufficient for your desktops, IP telephone systems and micro-servers.  An online unit is suggested for mini-servers and anything larger.

(source)

Output Power Capacity

Output Power Capacity is the amount of Watts or VA that the UPS can supply at a steady state indefinitely.  The unit can put out more power at time of need, i.e. supply more energy to start a computer, but then return to steady state.

Max Configurable Power

Max Configurable Power is the maximum amount of power the unit can supply for a short period of time, i.e. the amount of power the unit can supply to start a computer.

APC thought so, too, which is why they’ve made it easy to do just that (as long as you have the know-how – that’s where we come in!).  Listed below are the most commonly utilized APC communication protocols.  Depending on your model, you may find one or more of these options available:

USB Port: RJ50-to-USB(A) or USB(A)-to-USB(B)

Networking Port: RJ45-to-RJ45

Serial Port: DB9-to-DB9

EPO connector (Emergency power off)

Software

- HyperTerminal.

- Powerchute Business Edition.

- PowerChute Network Shutdown V2.2.4

- PowerChute Network Shutdown V3.0.0

Additional APC Knowledge Base resources:

- SIGNALLING CABLES: Windows XP Software & Cable Compatibility

- USB: How multiple USB devices connect to host devices. USB connectivity schematics

- NETWORK: How do you make a Network Management Card communicate on a network?

- HYPERTERMINAL: Adding External Batteries to an SU, SUM, SURT, or SUA series Smart-UPS

- SERIAL: What are the computer interface port specifications for the 3G Smart-UPS family?

Watts measures the real power drawn by the equipment (i.e. the actual power you’re consuming).

Volt Amps (VA) is the “apparent power,” or, to get technical, the product of the voltage applied to the equipment multiplied by the current draw. (i.e. the power you’re paying for).

As a rule of thumb, the VA rating is always going to be greater than or equal to the watt rating. The ratio of watts to VA is called the power factor.

Again, we admit it gets confusing. And that’s why we like to get beer involved.

Think about it this way:

The mug is always the same size, but the ratio of beer to foam is determined by the pour. I’m willing to bet you’d rather have more beer in your mug. In the same way, the lower the power factor, the lower the efficiency of the unit, and the lower the usage of available power.

While the UPS industry often works off a .6 power factor, APC has a .67 or higher standard on all of their single-phase UPS units. In efforts to be greener, APC is currently trying to move the power factor closer to 1, giving the unit the exact power it needs and saving energy at the same time. You’ll notice in some of our units that the power factor is .7 or higher, particularly with the SURT models which include power factor correction.

So, how is this helpful?
It’s important to know when sizing your UPS. Let’s use desktop computer as an example. On the nameplate, find the amperage (A) and voltage (V). Then, determine the VA by multiplying the V x A (likely 120 or 280). Now, you know the VA rating and can therefore purchase the correct UPS to support the unit.

Wait, where to the watts come into play?
Remember, efficiency, efficiency, efficiency. A unit with an output power capacity of 670 Watts / 1000 VA is more efficient then one with a capacity of 600 Watts / 1000 VA – just like these beers are more efficient then the foamy one above.

Still have questions? Contact our team of beer-loving experts at 410-521-1000.

Our goal is to provide our visitors with an easy way to purchase expertly reconditioned units online, and to learn about the other products and services we offer. Amongst these services is our new Comprehensive Protection Plan – the easiest and most efficient way to ensure complete protection for an entire UPS fleet. Under this option, customers purchase a number of service credits based on their current failure rate, and redeem them throughout the year. This program is being offered through our evolving partnership with APC.

We also include all user manuals on the individual product pages, as well as troubleshooting guides, so that information and answers are easily accessible. Visitors to the site can reach both our sales and support team directly via the Contact us  page.

This website is always evolving to best serve our customers. Please send us your feedback, or leave a comment below, as we will use it to make improvements to our content and offerings.