Introduction
The battery system in a UPS represents the heart of the power protection benefit. This key element performs two functions: (1) it delivers energy during a power outage, and (2) it stores energy efficiently for extended periods of time. That stored energy is instantaneously available when needed to support the critical load on the UPS. In order to perform the above functions reliably, the charge level of the battery must be maintained. At the same time, battery charging should be controlled to maximize system efficiency and, more importantly, to maximize the float service life of the battery system. 

Two types of battery charging schemes have traditionally been used for UPS battery systems. The older and more commonly known is the “float” charge, which involves applying a constant voltage charge to the battery continuously for purposes of maintaining full charge during day-to-day operation of the UPS. This works quite well in many conventional battery applications. However, battery life may not be optimal, due to overcharging, for batteries that are used very occasionally as in standby applications such as a UPS. In a UPS, the battery system may sit in float mode for many months, without ever experiencing a discharge. Float charging for long periods of time means that “trickle charge” energy is constantly forced into a battery which is effectively already full. This results in very gradual degradation of the lead plates (positive grid corrosion), and it can impact float service life.  

Standby applications are better suited for “opportunistic” charging schemes. The system Eaton® utilizes is called ABM technology, which is essentially a set of charger controls and automated battery tests. It is implemented in Eaton single-phase UPSs from 500 VA to 18 kVA and three-phase models from 10 kVA to 3.3 MVA. Opportunistic charging schemes like ABM allow for periods of time where the battery is being fully charged, and periods of time when the charger is disabled. This reduces the time that the battery is subject to grid corrosion when compared to a traditional float charger — a reduction in grid corrosion that yields a measurable increase in battery life for UPS applications.
 
ABM Operational Summary
As shown graphically in figure 1, ABM consists of three operating modes:

1. Charge Mode
2. Rest Mode
3. Test Mode

Charge Mode
The UPS enters the charge mode under any of the following conditions:

• Whenever the UPS is commanded to turn on
• After any utility power outage lasting longer than 15 seconds
• Whenever the battery is replaced (or the battery breaker is opened and re-closed)

 
In charge mode, constant voltage charging of the batteries is used to recharge a discharged battery after a power outage, or whenever the ABM process is restarted. Charge voltage target is set to the manufacturers’ float level, and charge current is greater than 0.1 C A. Constant voltage charging lasts only as long as it takes to bring the battery system up to a predetermined float level (there is a 100-hour maximum time limit). Once this level is reached, the UPS battery charger remains in constant voltage mode, maintaining a float level. The current is at trickle charge levels during this time, and a 24-hour clock is started. At the end of 24 hours of float charging, the UPS automatically performs a battery test (see figure 1) at two different load levels to verify that the battery is performing, and to collect data for comparison to previous and subsequent automatic battery tests. If the test fails, an alarm is activated on the UPS and also through the remote monitoring system that may be connected to the UPS. At the end of the test, the charger resumes constant voltage mode and remains in that state for an additional 24 hours.

Rest Mode
Rest mode begins at the end of charge mode; that is, after 48 hours of float charging, and after a successful battery test. In rest mode, the battery charger is completely turned off. The battery system receives no charge current during this mode, which lasts about 28 days. Then, the charge mode is repeated as described above. Since the battery clearly spends most of its time in rest mode, as a result, the following benefits are realized:

1. The battery is not subjected to constant forced charge current; therefore, overcharging is not possible.
2. Thermal runaway is not a concern with the charger off.
3. The battery system cannot be damaged by ripple currents, since the charger is off.
4. Positive grid corrosion is greatly reduced, allowing extended service life.

During rest mode, the open circuit battery voltage is monitored constantly, and battery charging is initiated if any of the following occur:

• A power outage lasting longer than 15 seconds
• The open circuit voltage (OCV) of the battery drops below a predetermined threshold after 10 days of rest mode (If OCV drops below the predetermined threshold during the first 10 days, an alarm is triggered)
• 28-day timer expires (end of rest mode)
• The battery is replaced, or the breaker is opened and re-closed

Test Mode
There are two other battery tests that are performed as a part of the ABM cycle. The first is meant to detect battery conditions which could lead to thermal runaway. The bulk charging period is timed and if the float voltage is not reached in a predetermined time, an alarm is triggered and the charger is shut down. The second test is performed after the charge cycle is completed (i.e., at the beginning of rest mode). The battery is discharged at about 15% load for up to 6 minutes, then at 50% load for 45 seconds.. Upon reaching this point, the battery voltage is measured. If the voltage is below a specified threshold, dependent on the load, then an alarm is signaled indicating the battery is nearing the end of its service life and should be replaced.

Other Modes
ABM may be disabled by the user or an Eaton field technician at any time. In this case, the UPS battery charger operates as a conventional float charger only. This is recommended when a wet cell or flooded electrolyte battery is used with the UPS. ABM is intended for use with VRLA batteries. As a result, wet batteries do not benefit from ABM controls.

Many observers express concern regarding the ability for the battery to maintain capacity if called upon to support the UPS near the end of its rest mode. In other words, how much battery capacity is available on day 27 of a 28-day rest mode? Using a 15-minute battery as an example, under this condition, the battery would provide all but about 30 seconds of its 15-minute backup time. This is proportionally true for other battery sizes, as well. The intent in selecting the 28 day rest period is to limit the loss of capacity to approximately 5%.

ABM Performance
The ABM process above describes the benefits of using a “opportunistic” charging scheme. Those benefits, specifically extended service life, are in fact substantiated by data and empirical testing performed by Eaton as well as other independent sources. Some of this testing is recent and some of it was performed as many as 25 years ago.

ABM is not a new battery management feature. In fact, Eaton has been using ABM in its UPS products for 27 years, and it has proven itself beneficial in the field for more than two decades.

Note that in figure 4, the curve identified as “23/23 days” represents a float charger, and ABM (as implemented today) is best represented by the curve labeled “12/23 days.” At an ideal 25°C (77°F), there is a theoretical increase of six years in battery service life reflected in this analysis.

The above information shows a clear benefit of cyclic charging in UPS applications, both in simulated and in actual performance tests. These results would not be expected with non-VRLA batteries or in applications such as motive power chargers where the battery is discharged/recharged daily and therefore not deployed in a standby application.

Summary
ABM is unique in the UPS industry, but similar opportunistic designs are utilized by battery manufacturers and battery charger designers worldwide. The criticality and cost of the battery subsystem of any UPS dictates that special consideration be given to battery longevity. Additionally, with environmental concerns relating to battery removal and disposal becoming more prevalent, it is desirable to reduce the frequency of battery replacements during the life of the UPS electronics. ABM offers a significant benefit over conventional “battery monitors” which don’t provide charging control, and “multi-stage chargers” which protect the battery, but do not provide useful extension of battery service life.

Over the past 27 years, ABM has proven itself in both large and small UPS products, from the desktop to the data center, and from the medical lab to the factory floor. Anywhere a UPS is installed, a battery system is depended upon to provide backup power protection for critical business processes and even for personnel safety. The battery is all too often ignored as a maintenance-free product, not requiring attention or inspection. This neglect, though common, can be costly and possibly disastrous. The ABM system, by its nature, helps to provide early detection of problem batteries and thus protect the battery from unnecessary failures like electrolyte dry out and thermal runaway, while functioning to extend the useful life of this key component of power quality.

Demands on data centers are increasing, while the space and budgets for these facilities stagnates. As data center staff are forced to be more efficient, they turn to metered power distribution units (PDUs). A metered PDU offers the ability to conserve resources – money, personnel hours and space – at a granular level, freeing up staff to concentrate on more strategic tasks.

1.  Reduce cooling costs.
The cost for regulating a data center’s temperature can eat up an operating budget. Modern hot-air containment solutions help to reduce costs, but the lower operating temperatures for legacy rackmount PDUs mean they can only help so much. Newer metered rack PDUs have a higher operating temperature – up to 140°F/60°C – meaning a big cut to the cooling cost of your facility.

2.  Maximize space
Instead of requiring a dedicated infrastructure rack, a metered rack PDU is designed to utilize space that would otherwise go unused: vertically mounted inside or on the side of a server rack or enclosure. Not all vertically mounted metered PDUs are created equal, though. To make the best use of space, a rackmount PDU should have low-profile circuit breakers and a width optimized for side mounting to avoid interfering with access to hot-swap fans and power supplies.

3.  Prevent accidental disconnects
Downtime caused by a plug getting bumped out of place is an occurrence that happens too often in data centers. Most rack PDUs rely on external clops or cable trays to secure plugs. While those methods of prevention are effective, they require additional time from staff and represent an added cost. Next-generation metered rack PDUs offer built-in IEC outlet grips, which provide the same prevention without the need for proprietary power cords or bulky additions. 

The right metered PDU can provide all these resource-saving benefits. With the money, personnel power and space now available, your data center will be better able to meet changing computing demands.

Power distribution is facilitated through different pieces of equipment that take the power
conditioned by your uninterruptible power supply (UPS) and send it to your IT equipment.
Power distribution solutions can manage and even control energy consumption in smaller
environments as well as large data center applications.  Distributing power efficiently results
in reduced operating costs and increased reliability.

Rack power distribution units, also known as rack PDUs, are a key component to any IT environment.  They do exactly as the name suggests and distribute power to network equipment within racks.  A common misconception is that they’re just power strips, and at first glance, they even look like it, but modern rack PDUs provide benefits a simple power strip cannot.  Some of the valuable features include network connectivity, environmental monitoring and remote access, but we’ll get more into that later. This guide should help you get familiar with power distribution ,gain interesting insights and learn some key considerations for future IT investments.

To determine the level of protection you require from a UPS consider the following criteria:

• How critical is the application you need to protect?
• Do you need complete or partial protection?
• What size UPS do you require? VA, watts, sizing calculations?
• Battery run time required in minutes? In hours?
• What software and network considerations do you have? Platforms, SNMP, remote monitoring etc.?

The Powerware series of Single-phase UPSs protect against the most common power problems. Series 3 and 5 keep your system from failing due to outages and surges, and the Powerware Series 9 offers comprehensive protection against all nine causes, minimalizing opportunities for component stress, burned circuit boards, data crashes and program failures. Series 9 UPSs are recommended for mission-critical applications like high-end servers, hospitals and voice over IP applications.

Birds are chirping, flowers are blooming and spring is in the air.  Yard sales will soon become Saturday morning’s most prolific event for homeowners set on cleaning out their clutter. Are you taking the same steps to clean up your IT environment?  At this point, you may have just finished setting up some of the precious new IT equipment that you weren't able to squeeze into the 2016 budget or you’re beginning to finalize your spend for this year.  Regardless of your situation, here are a few tips to be more successful in your IT spring cleaning adventure and prepare for a more productive 2017.

1. Examine your infrastructure: Take a closer look at your needs. A big part of spending your 2017 budget effectively is understanding what needs to be upgraded or added most urgently.  In order to do so properly, you’ll need to assess your environment.  Take a detailed inventory including not only servers, switch and storage components; but also the power infrastructure, cabling, and environmental aspects of your IT infrastructure.
   
   
2. Define fault points: Reducing points of failure within your IT infrastructure is critical to maintaining business continuity. As you’re preparing to deploy new equipment or evaluating the needs for your 2017 spend, take a moment to recognize potential points of failure:
   
   
   1. Has your UPS been alarm gone off over the past few months, begging and pleading for a new battery? It may be time for battery or even unit replacement. 
      
   2. Have you repeatedly received over temperature alarms within your rack enclosures? Take this time to more properly balance your equipment within the rack in hopes of alleviating these problems.
      
   3. Have you been paying close attention to power consumption? Take a close look at, not only your UPSs but your monitoring software and rack power distribution units (PDUs). Take advantage of the capabilities your technology offers. For instance, turn off unused outlets on your PDUs and better control your power utilization if possible.
      
   4. Have you checked all plugs and connection points? Take a moment to make sure all plugs and connections secure, as well as electrically sound from a safety standpoint.
      
      
3. Tidy up while you’re at it: As you're adding, removing and relocating equipment within the rack, address any needs you have around cable management. Tighten and replace cabling where applicable, utilize free space behind the cooling components of your server, switch components to better improve airflow, and use cable ties to secure network and power cabling infrastructure to the sides of your enclosure.

IT maintenance is a must, whether it’s your network closet itself or the equipment that resides in it, so try to schedule a reoccurring time to do some technology housekeeping. It will not only help you on a daily basis, but it will look like you truly value your company’s investment. Who doesn’t like getting kudos from the boss? I hope these 3 tips are helpful reminders that you can put to use. What are some of your most efficient cleaning tips?