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What’s The Difference Between AC and DC Power?

Posted by Eric Giacomini on Oct 26, 2017 3:45:00 PM

Originally posted on Mar 2, 2015 - updated Oct 26, 2017


Do you question the best way to transmit electricity to network devices throughout your data center? Some argue that alternating current (AC) is the less expensive and accessible method of using power, while others claim that it’s safer and more efficient to use direct current (DC).

What’s the difference between the two types of current? In a nutshell, AC wavelength changes direction, while DC’s is constant, or a “direct,” line. In the U.S., AC wavelengths oscillate at a frequency of 60 Hz per second. Due to the fact that AC power changes direction, you simply need a transistor to adjust the voltage, or force that pushes the current.

The voltage in a DC supply unit (such as a fuel cell), by comparison, cannot be changed unless the power supply is altered or turned off, such as with a high-voltage direct current (HVDC) system. DC is, therefore, less efficient and affordable to transmit than AC power, but it can be accomplished.


What’s the better power solution for your data center? The truth is that they both have specific uses. It’s not a matter of choosing one or the other. In fact, migrating away from AC would be impractical and difficult because your facility is most likely wired to receive it already. It’s much less expensive and much more practical to use AC directly from the power grid for your daily data center power needs. Most data centers take AC, convert it to DC to power fuel cells and batteries, and then convert it back to AC to power their machines.

Server Technology carries a full line of rack mount power strips that allow you to feed AC or DC power to your data center equipment cabinets or remote site all while providing advanced power monitoring metrics and management capabilities.

 View AC PDU Products     View DC PDU Products



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Topics: data center power, DC power, AC Power

On the Subject of Electrical Inequality

Posted by RJ Tee on Aug 18, 2017 3:35:34 PM


I must admit I have been thinking a lot about quality lately.

Our data center industry, at its core, is about power correction, conditioning, and quality.  The ability of a mission-critical electrical system to deliver the proper sine wave to the server is a multi-billion-dollar industry. 

(My apologies in advance to the mechanical minded for such unilateral statements.)

But as I ponder that fact, I can’t help but wonder why there's a tendency to buy only the best switchgear and generators, and pinch pennies when it comes to rack PDU’s?

Here are a few thoughts on the paradox of such logic:

You don’t plug a server into a generator.  Indeed, this practice has never existed.  And the truth is that the first encounter your IT equipment has with the electrical system is not with any of the big ticket electrical items such as UPS or generator, but with the lowly power distribution unit in the back of the rack.


This powertrain doesn’t have a caboose.  Don’t worry, the average rack PDU doesn’t get offended.  But it would like to remind you of its critical position in the powertrain.  In a mission-critical one-line, there is no portion of the infrastructure that is less important than another.  In data centers, the powertrain is all engines – if any portion fails, the entire enterprise comes to a standstill on the tracks.     

Read the Uptime is Revenue Industry Brief Today

Your budget afterthought.  In most data center projects, the electrical build is the largest single line item in the budget.  And within that budget, the choice of rack PDU usually accounts for 2-3% of the overall spend.  That’s all.  So doesn’t it make sense to buy the absolute best rack PDU’s for your IT equipment, and spend your time and effort scrutinizing the largest components?  Keep in mind that fractional savings on switchgear, for example, would more than pay for the highest quality rack PDU available.   

For more ideas about how to improve the quality of your rack PDU’s, you can check out the entire Server Technology product line here.

click to view the Servertech rack PDU buying guide

Topics: data center power, rack PDU

Innovative Solutions For Government Clients: Part 2

Posted by RJ Tee on Jan 23, 2017 11:30:00 AM


In Part 1, we explained how the federal government is improving data center efficiency, lowering overall energy costs and optimizing their data center environments. In our next segment, we will dive deeper into solutions that can help meet those critical needs.

Federal Sales Manager Jason Mollicone discusses how Server Technology’s expertise with intelligent PDUs positions the company to best provide solutions to the power challenges faced by the federal government. He says the need for remote monitoring and management has become a priority over the past couple of years.

“We’re really starting to see those conversations come up in the federal space,” he says, explaining that Server Technology’s intelligent rack power solutions – from our Smart rack PDUs to our Switched PDUs - can help clients drill down to the outlet level, if needed, to see individual IT device power consumption and trends while allowing all necessary data points to be collected.

“Also, you have remote access into your PDUs, so if something needs to be turned off or rebooted remotely, you can do so very quickly,” he says. “In addition, from a security perspective, you can lock individual outlets to ensure proper access is granted prior to plugging in additional devices.”

On the Front Lines of Power Trends

A big buzzword in not only the government space, but with all data centers – is efficiency. Mollicone says one of Server Technology’s efficient solutions, Alt-Phase technology, can greatly enhance efficiency in three phase power applications. Alt Phase technology allows customers to easily balance loads by cording outlet by outlet instead of bank by bank, as you do in a traditional 3 phase rack PDU. This improves operational efficiency by allowing the customer to properly utilize available power in each rack, while improving air flow. In addition, it keeps phases well balanced, which increases power efficiency and lowers overall costs. 

The Impact of DCOI

With the institution of the Federal government’s Data Center Optimization Initiative (DCOI), which requires agencies to optimize their existing infrastructure and report on their efforts to do so, Mollicone says the pace of finding more efficient solutions for government clients has quickened.

“These data centers are very expensive to operate and maintain,” he says. “So, the more we can do to help lower costs, while providing the right solution, the better.”

Server Technology’s solutions for our federal clients also include the ability to provide more outlets per rack, which is found in our High Density Outlet Technology (HDOT) PDUs. The reason this is crucial, Mollicone says, is because the government’s recent consolidation efforts means we’re seeing rack densities increase.

“Equipment that may traditionally require three or four rack PDUs can now be implemented in two rack PDUs,” he says. “The more outlets we can put into one rack PDU means fewer PDUs are needed overall, resulting in less total hardware, lower costs and cleaner airflow, all while minimizing deployment time. That’s a good thing because it means there is less to manage and speaks very well to the goals of DCOI.”

Ultimately, it comes down to serving the client’s needs and developing innovative solutions to meet – and exceed – their expectations, a value Server Technology was founded on.

“If you can understand their challenges and have a solution that touches on all those points, there’s nothing more powerful,” he says.

Topics: data center power, efficiency, government data center

Three Things You Don’t Know About Your Own Data Center (But Should)

Posted by Josh Schaap on Jan 12, 2017 1:19:38 PM


Originially posted Jan 12, 2017, Updated Aug 09, 2017

This is your data center speaking. You think you know me pretty well, right? After all, you spend almost all of your time around me. Take a harder look, however, and you’ll see that there are some important things about me that you aren’t aware of! 

Ask yourself the following questions:

How many devices do I have?

Take a guess; I’ll bet you’re off by at least 15 or 20 pieces of hardware that have gotten buried while you’ve been expanding. You keep adding new components like servers, racks and switches; but you don’t monitor any of these devices in real-time. As a result, you’ve lost track and many of the devices are now sucking up power without your knowledge and steering you ever-closer to network capacity.  Learn how to find and get rid of zombie servers in this blog.

What is my ideal temperature?

I’ve been running at a cool 65 degrees ever since I was built. Did you know, however, that I am capable of safely operating at a temperature of about 15 degrees warmer? No, you didn’t, because you never experiment with different settings! If you did, you might find that you could significantly reduce your monthly expenses by raising the temperature on your cooling system.

How much power do I use on a daily basis?

You know how much you pay for electricity. But you don’t know how much power each one of your devices actually uses. A data center power monitoring solution, like the All-In-1 Solution, will provide this information, and will distribute it directly to your mobile phone—so you can see every device on your network, and how much power each one is using in real-time. So, it’s time to get to know me better. After all, I’m one of the most critical parts of your entire organization. So I suggest you check out Server Technology’s advanced line of data center monitoring products to see how you can protect me.

Need better insights into your data center?  Try Sentry Power Manager for a 120-Day Free Trial!


Topics: data center power, SPM, Sentry Power Manager

The Big Decision: Smart vs. Switched Data Center PDUs

Posted by Erik Stabile on Dec 28, 2016 4:37:24 PM


Recently, many customers have inquired about whether they should implement smart or switched power distribution units (PDUs) into their data centers. After all, when looking at the two products side by side, they appear to be almost identical, as both products offer the following features:

  • Branch circuit protection
  • Input current monitoring
  • Environmental monitoring
  • Access, security and communications
  • An expansion module
  • Interoperability with Server Technology’s Sentry Power Manager (SPM)

There is one major difference, though, between smart and switched PDU: A switched PDU provides the ability to toggle power on and off on a per-outlet basis. As such, a switched PDU typically offers more control and flexibility on an outlet where it’s being used.

Conversely, a smart PDU will provide the same level of critical power and environmental data, but will not allow you to make changes to the outlet from a central location. Smart PDUs are more for monitoring and reporting purposes.

Here are some reasons a business would consider investing in a switched PDU:

Rebooting and power-up sequencing: When a core network device fails, it doesn’t always need to be taken in for service, or manually inspected. Sometimes, all it takes is a reboot to correct the underlying error. Reboots aren’t always easy, though, particularly for multisite data centers or colocation facilities. They can be time consuming and expensive, if they require sending technicians out to the actual data center to complete the task. Using a switched PDU, reboots can be performed remotely from a Web interface—thus potentially eliminating the need to deploy service technicians.

Switched PDUs also come in handy following power outages. In this case, operators need to be careful to avoid power surges when powering up equipment, as this can lead to additional network downtime. A switched PDU can enable staged power-up sequencing, allowing the network to ease back up to scale. 

“Locking out” unused outlets: Resources like space, power and cooling come at a premium price in medium-to-large data centers—especially in growing facilities. For this reason, it can be very challenging trying to deploy new IT equipment safely. Before a device can be installed into a cabinet, it’s vital to track the cabinet’s power usage and environmental conditions over time. Otherwise, installing the device could prove to be dangerous.

Suffice to say, in a medium-to-large environment it can be very difficult trying to keep a running historical account of each cabinet’s usage history and available capacity. With the help of a switched PDU, though, managers can easily identify outlets which are not safe for use based on aggregated historical data. Then, the outlet can be toggled off so that no equipment can be added to it. 

Scheduling power loads: Many data centers waste power by continuing to run equipment during off-hours when the network is not being fully used, usually because it is more cost-effective to keep the equipment running and saves time over having to manually reboot. A switched PDU allows operators to strategically schedule each outlet to avoid wasting power. As we explained in this white paper, one government agency was actually able to reduce power usage in their POC data center by an average of 50 percent for any given week using a switched PDU. It should also be noted that switched PDUs are ideal for identifying and eliminating “zombie” servers, or comatose servers that use large volumes of data over time by running idly.

The aforementioned points are just some of the benefits to using a switched PDU, and the white paper contains many more.

Keep in mind, though, that determining the right type of PDU can be very complex. And in some cases, a switched PDU may not be the best choice to fit your needs. For example, if you are managing a single facility, there may be little need to use remote management technologies; your staff members may prefer to perform outlet changes manually. The scope of your operation, your risk factor for downtime, your budgetary allowance and your staff members’ preferences should all be considered when deciding what type of PDU to use.  

Server Technology can outfit your business with smart or switched PDUs—and both can be equipped with Per Outlet Power Sensing (POPS) technology capable of reporting voltage, kW power, current, crest factor and power factor. Server Technology also offers metered and basic PDUs. To see a side-by-side comparison of all of Server Technology’s PDUs, click here.

Topics: switched PDUs, data center power, smart pdus

The One, The Only: HDOT With POPS

Posted by Josh Schaap on Dec 22, 2016 9:17:40 AM


What do you get when you take the flexibility of Server Technology’s High Density Outlet Technology and combine it with Per Outlet Power Sensing? A pretty amazing product, says Vimal Bhakta, Senior Engineering Manager for Server Technology.

“It’s great,” he says with a smile.

If you haven’t already, take a second to watch Vimal share the good news about HDOT POPS PDUs in our new video:

In the video, Vimal runs down the key benefits of adding POPS technology to our award-winning HDOT alt-phase rack PDUs. He discusses how data centers can use this winning combo to find solutions for density, capacity planning and remote management.

HDOT’s alternating phase power is designed for three rack power configurations, and with each configuration, there are four product types to choose from, depending on the level of control you need:

Thanks to its modular design, each HDOT product type gives customers the flexibility to configure the location and quantity of C13 and C19 outlets on the PDU. As a result, there are literally thousands on thousands of configurations possible. To get a sense of how customizable our PDUs really are, check out our Build Your Own PDU tool which walks you through four easy steps to building the perfect power solution for your data center. It’s so remarkably easy that you can even build a PDU right from your tablet or phone.

So, why HDOT? The short answer is that it provides 20 percent more outlet real estate than conventional outlet-based PDUs. We’re able to achieve this by removing unneeded material around the outlet and group them as close together as physically possible.

HDOT PDUs also feature high native power cord retention and alternating phase power for cable management and load balancing. Ultimately, this helps customers operate at the highest efficiency possible.

Available in Smart and Switched POPS, these PDUs provide +/- 1 percent energy consumption accuracy at each outlet for typical data center equipment loads. As a bonus, it’ll also help you identify abnormal rack equipment power behavior such as zombie servers on the data center floor.  

In the end, HDOT is the most reliable and adaptable customer power solution for data center rack equipment, Vimal says.

“HDOT is a true game-changer out in the PDU market,” he says. “Customers love it … I love it … Only with Server Technology will you Stay Powered, Be Supported and Get Ahead.”

Topics: data center power, intelligent PDUs, rack PDU

Use Top Shelf PDUs for your Colocation

Posted by Erik Stabile on Dec 19, 2016 8:43:08 AM

BeautyGroupColor_small.jpgIf there’s one need you can’t skirt around as a colocation provider, it’s rack-level power management.

Power is expensive, and there is too much at stake in your mission critical environment to go without a reliable network of intelligent power distribution units (PDUs)  that can track daily usage, prevent outages and respond to environmental alerts.

Here at Server Technology, we offer best-in-class power distribution units (PDU) that are ideal for use in large colocation centers. Here are some reasons why you should consider Server Technology for your rack-level power management needs:

Fast shipment times: Oftentimes, vendors will make customers wait several weeks to receive products, which is far too long. With Server Technology, you will always be guaranteed fast shipment times. We store our products in our own warehouse, which saves a great deal of time. We are able to ship our Fast Movers in just a few days.

Get more, pay less: Our HDOT PDUs offer more outlets per form factor than anything else on the market. Buying one HDOT PDU from Server Technology is like buying two or more standard PDUs, and more power density means more white space for future data center growth. Choose a PDU with Alternating phase outlets, which alternate the phased power on a per-outlet basis instead of a per-branch basis. This allows for shorter cords, quicker installation and easier load balancing for 3-phase rackmount PDUs. Shorter cords mean less mass, making them less likely to come unplugged during transport of the assembled rack.  Learn more about density solutions.

Custom design: Why settle for one-size-fits all solution, when you can use our Build Your Own PDU portal? We make it possible to choose your type of PDU (metered or smart or switched, smart POPS or switched POPS), and then add specific power, plug and color options.

Best value: Our new High Density Outlet Technology Switched PDU with Per Outlet Pops Sensing (POPS) technology solves three challenges in one:  Power density, capacity planning and remote management.

Server Technology is your go-to provider for all of your PDU needs. You’ll be hard-pressed to find a vendor that offers as high a level of quality, and support.

To get started, click here.  

Topics: data center power, colocation

Innovative Power Solutions for Government Clients: Part 1

Posted by Erik Stabile on Dec 7, 2016 10:51:19 AM


Helping the federal government operate more efficiently may sound like a Herculean task, but it’s one the Power Strategy Experts at Server Technology are well prepared to take on. With years of experience working with the federal government, we proudly help the U.S. Air Force, U.S. Coast Guard, NASA, the Army, Navy and others with their data center power needs.   

There are some unique needs and initiatives driving change in the Federal data center space. We’ll explore some of those in this, the first of a two-part series.  

Data Center Evolution: The Path to High Efficiency 

Charles Darwin is quoted as saying “It is not the strongest or the most intelligent who will survive but those who can best manage change”. Technology presents real changes in our lives and as it continues to advance, so must our actions and behaviors.  The ability to handle rising rack densities and scale while improving efficiencies in the data center is more critical than ever.  As a result, the Federal Government continues to improve and optimize their approach to continual evolution. Part of their improvements lie in the Data Center Optimization initiative (DCOI), designed to improve efficiency, lower operation costs and enhance overall optimization. Building off of the success of the 2010 Federal Data Center Consolidation Initiative (FDCCI), DCOI looks to continue consolidation efforts by requiring existing data centers to operate at apower usage effectiveness/PUEbelow 1.5 or face closure by September 30, 2018. For Nevada-based Server Technology, “These requirements will call for critical data center infrastructure improvements, says Federal Sales Manager Jason Mollicone. As a result, Mollicone says, “This creates a lot of opportunity for us to address real customer challenges,” he says. In order to reduce PUE and increase efficiency, monitoring and reporting of data must be implemented. Our solutions allow the customer to monitor, collect and report on the data needed in order to be efficient and successful towards DCOI goals. 

“Today, the federal government is putting more enforcement in place to optimize and improve facilities to ensure that funding and energy are being used effectively,” he says.  

Each initiative instituted by the Office of Management and Budget (OMB) includes data center consolidation and server room optimization, which will help the government operate its data centers more efficiently and effectively. “We’re helping customers put real metrics in place to say, ‘OK, here’s what’s going on in our data center, and here is how we can make the necessary improvements to improve efficiency’” Mollicone says. “We want to put accurate data behind everything and take out the guess work so the customer can be in the best position possible.” This data can be used to make decisions, such as determining which facilities are not efficient enough to remain operational. Other times, it means making adjustments and upgrading facilities to make them run more efficiently and save taxpayer dollars, Mollicone says.  

“It’s about creating a more efficient environment that helps lower costs, save energy and optimize data center infrastructure,” Mollicone says. “Server Technology’s solutions are great because they allow the customer do that at the rack level, which is a key component in operating and maintaining an efficient environment.” 

Next, in part two, we’ll explore some of the solutions Server Technology has developed to serve our federal clients.  

Topics: data center power, government consolidation, server technology solutions

Five Key Benefits of HDOT Switched POPS PDUs

Posted by Erik Stabile on Dec 6, 2016 10:06:39 AM


Not that long ago, we told you about our customer-focused approach to design and production. We showed how our products often result from working closely with customers to determine their power distribution needs. Now, we’re excited to roll out the newest evolution in customer-driven design: the HDOT Switched POPS PDU 

With this HDOT® Switched POPS® (Per Outlet Power Sensing) unit, we’ve unleashed one of the most powerful additions you can make to your data center floor, giving you complete control and the peace of mind that comes with it.   

Click Here To Build Your Own HDOT PDU  with Alt-Phase and POPS

Here are the top five reasons to consider HDOT Switched POPS:  

  1. All the right outlets in all the right places: featuring a slimmer form factor and stacked outlets, our HDOT (High Density Outlet Technology) PDUs are designed with maximum density in mind. With HDOT technology, we’re able to fit as many as 43 C13s in a 42U high network managed PDU device, which is more than 20 percent smaller than PDUs employing standard outlets.  
  2. High native cable retention: Our PDUs feature high cable retention to reduce accidental disconnects by making sure power cords are solidly connected to devices. Our PDUs are tested for up to 12 pounds pull strength, eliminating the need to purchase ancillary locking cord devices.  
  3. Easy load balancing with alternating phase: With HDOT technology, you’re not only getting the highest outlet density available in a network-connected rack PDU, you’re also getting three-phase powered wired in an alternating fashion per outlet. This helps simplify load balancing, reduces cord lengths and stimulates better airflow.  
  4. Build it yourself: With Server Technology’s Build Your Own PDU tool, you can select the number and arrangement of outlets that best suits your data center power needs. Our new four-step configuration process graphically walks you through customization options such as voltage, amperage, phase, plug type, input cord orientation, outlet configuration, connectivity and color selection. 
  5. Options galore: HDOT PDUs are available in smart, switched and POPS. With the addition of the switched line, you’re able to remotely turn outlets on, off or reboot them – either individually or as a group. See our complete line here 

With POPS onboard, our PDUs provide +/- 1 percent billable-grade accuracy for energy consumption at each outlet for typical data center equipment loads. The POPS technology also includes warnings and alarms for current, power and power factor, both for low and high values.  

Learn more about HDOT Siwtched POPS PDUs here 

Topics: data center power, Per Outlet Power Sensing, HDOT Switched POPS

Monitoring At The Cabinet, Zone And Location Levels

Posted by Josh Schaap on Nov 23, 2016 10:54:41 AM


Pardon the cliché, but knowledge really is power, especially when you’re dealing with actual power in a data center. Take, for instance, the knowledge of how much power your cabinets need and how much power is available, or knowing the IT load. With that information in hand, you can solve a number of data center problems.

Thanks to Server Technology’s award-winning Sentry Power Manager, you can see the amount of power used in a cabinet and roll this information up into groups – or zones – of cabinets.  Alternately, you can roll up power information into locations in order to gain several key metrics that will help you make better decisions, including:

  1. Monitoring at the cabinet level: Seeing your power usage allows you to identify potential hot spots in your data center. Also, knowing the amount of cabinet power usage lets you run reports to identify cabinets with the power and space availability for the installation of new devices. Other advantages: you can pinpoint the cabinets that have either exceeded capacity or will exceed capacity at some future time period, based on the current growth rate. SPM’s Predictive Trending tools designed for power and temperature give you reliable estimates - based on past growth – about when you’ll exceed power or cooling thresholds.
  1. Zone level monitoring: When you have a solid idea of your zone level power usage (by rolling up cabinet-level power monitoring) you can effectively compare power monitoring information from the UPS or RPP against actual device usage. Also, this information can be used to see how many additional cabinets can be installed within a zone. This is important because power trends and reports provide the worst-case power load levels for the purposes of planning.
  1. Location level monitoring: When you’re planning for the allocation of new cabinets, knowing the power usage per location helps. With this knowledge, you can gain a better understanding of how many new cabinets could be supported, based on either the current infrastructure or by adding a new infrastructure.

Ready to learn more about Sentry Power Manager? See the top six reasons why it’s a data center staple or download a free evaluation copy today.

Topics: data center monitoring, data center power

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