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Critical Power Blog

Capacitors, UPS

UPS Capacitor Replacement: When, Why, How? (Video)

While much attention has been given to the importance of regularly replacing uninterruptible power system (UPS) batteries, there is also a lesser-known, often-overlooked component that cannot be ignored: the capacitors. After batteries, capacitors rank among the most common UPS elements susceptible to failure. Proactive attention to these components can extend the life of the UPS system and optimize the protection of your critical equipment.

Unified Power is the largest independent provider of mission critical power services in the United States. From battery preventive maintenance to battery capacity testing, UPS preventive maintenance and more, we can service any of your needs. Have a specific question about your specific power needs? Learn about all the power protection services we offer.

Education, UPS

Which UPS Topology is optimal for your environment?

The central design of an uninterruptible power system (UPS) is categorized as its topology. Of the three primary UPS technologies available today — standby, line-interactive and online — each offers different performance characteristics and varying degrees of protection.

It’s important to recognize that not all UPS’s are not created equal.

Determining the best topology for your facility depends on a number of factors, including the level of reliability and availability required, as well as the type of equipment being protected and the overall application/environment.

Various UPS topologies are appropriate for different uses, but no single UPS type is ideal for all applications. Consider the following:

Standby — Also referred to as an off-line or passive system, standby topology provides the most basic type of UPS protection. Safeguarding connected equipment against three of the nine most common power problem — power failures, sags and surges — the standby UPS allows equipment to run off of utility power until it detects a problem.

At that point, the UPS switches to the battery. Standby UPS’s are best suited for less critical applications such as office environments, provided that the power supply is not subject to frequent disruptions.

While an attractive alternative from a cost perspective, the downside to standby UPS’s is that they do not buffer equipment against other power anomalies, and they must resort to batteries frequently, which can reduce battery run time and service life.

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Line-interactive — A UPS with line-interactive topology is designed to shield connected devices from power failures, sags and surges like a standby model does, but it also provides protection against under- and over- voltage conditions.

Typically used to safeguard enterprise network and IT applications, the line-interactive UPS is controlled by a microprocessor that monitors the quality of incoming power and reacts to fluctuations. One of the biggest advantages of the line-interactive topology is that it compensates for under voltage and over voltage circumstances without using the batteries.

These systems provide more protection than standby UPS’s, with better power conditioning and regulation that helps prolong battery life. Battery usage is lower than a standby UPS, but still higher than an online model.

Online — An online or double-conversion UPS is designed to deliver continuous protection against all nine of the most common power problems.

Supplying a consistent power quality regardless of any incoming instabilities, the output voltage of an online UPS is entirely regenerated by a sequence of AC to DC conversion, followed by DC to AC conversion in order to create power supply without any electrical interference.

During erratic power or fleeting disturbances when AC input power falls outside of preset tolerances for line-interactive mode, the online UPS switches to online double-conversion mode, completely isolating equipment from incoming power.

If power is lost altogether, or the input power exceeds the tolerances of the rectifier, the UPS will rely on the battery to keep loads operating, then convert back to high-efficiency mode when it is safe.

Online UPS’s are the best choice for critical applications or those involving highly sensitive equipment, such as data centers, communications hubs and other mission-critical installations where continuous, clean power is a business-critical requirement.

While all three UPS topologies outlined above meet the input voltage requirements for IT equipment, there are significant differences in both performance and demands on the battery.

If you need assistance determining the optimal topology for your environment, Unified Power can help you to properly identify and compare systems.

Still have questions? Get a response immediately.

Click above to get started or call 240.772.1710 for instant help.

Batteries, UPS

10 Things You Need To Know About UPS Batteries

While undeniably the heart of any uninterruptible power system (UPS), batteries unfortunately are also the most vulnerable aspect. In fact, battery failure consistently ranks among the most common causes of load loss. Understanding how to properly maintain and manage UPS batteries is not only instrumental to extending their service life but can also help thwart costly downtime. Bolster your battery knowledge with these 10 truths:

1. All batteries will experience an “end of useful life”The IEEE defines a UPS battery’s “end of useful life” as the point when it can no longer supply 80 percent of its rated capacity in ampere-hours. At this stage, the aging process accelerates and you should replace the battery. Although the average lifespan for VRLA batteries is three to five years, actual life can vary dramatically due to environmental conditions, the number of discharge cycles and the amount of maintenance received.

2. Batteries die for a variety of reasons – Among the most common causes of battery failure are high or uneven temperatures; inaccurate float charge voltage; loose inter-cell links or connections; loss of electrolyte due to damage or drying out; lack of maintenance; and aging.

3. VRLA and VLA are the two most common types of UPS batteries – Valve-regulated lead acid (VRLA) batteries, also known as sealed or maintenance-free, are batteries that have been encased to prevent any liquid from leaking. Vented Lead Acid (VLA), also known as flooded or wet cell, are comprised of a hard enclosure, lead plates and an electrolyte that allows the flow of current. Don’t miss our next blog, which will explore both of these battery types in much greater detail.

4. Different UPS systems use different batteries – While basic battery technology — and the risks to battery life — remain the same regardless of UPS size, there are some differences between applications. Smaller UPS’s (250VA to 3kVA range) typically contain a single VRLA battery, while the use of wet-cell batteries becomes much more common in bigger systems.

5. Your UPS maintenance plan should cover the batteries, too – A solid, comprehensive service plan will include both the UPS components and the batteries. Regularly scheduled preventive maintenance visits allow trained technicians to inspect, test, calibrate and upgrade battery components, ensuring factory-specified performance and longevity.

6. The battery type will dictate maintenance requirements – The type of batteries will impact which maintenance tasks need to be performed and their frequency, with wet cell batteries requiring more maintenance than VRLA. However, even batteries that claim to be “maintenance-free” still need regular inspection, cleaning and testing.

7. Stored batteries require attention, too – If UPS batteries sit unused with no charging routine, their life will decrease. Due to the self-discharge characteristics of lead-acid batteries, it is recommended that they be charged every three to four months when in storage to avoid permanent loss of capacity (which will occur between 18 and 30 months). To prolong shelf life without charging, store batteries at 10°C (50°F) or less.

8. There is a difference between hot-swappable and user-replaceable batteries – Batteries can be both hot-swappable and user-replaceable. Hot-swappable batteries are able to be changed out while the UPS is running. User-replaceable batteries, which are generally found in smaller UPS’s, indicates that no special tools or training is needed to replace them.

9. A battery’s discharge rating is key to measuring performance – Batteries are generally rated for more than 100 discharges and recharges. However, many will display a marked decline in charging capacity after as few as 10 discharges. The lower the charge that the battery can accept, the less runtime it is able to deliver. Be sure to look for batteries with a high-rate design that sustains stable performance for a long service term.

10. Thermal runaway can have explosive consequences – Often occurring without any warning signs, thermal runaway takes place when the heat generated in a lead-acid cell exceeds its ability to dissipate it. Typically caused by overcharging, excessive charging, internal physical damage, internal short circuit or a hot environment, thermal runaway can result in an explosion, especially in sealed cells.

Batteries, UPS

Knowledge is Power: Understanding UPS battery options

When it comes to the batteries within uninterruptible power systems (UPSs), one size doesn’t fit all.

In fact, for decades, most smaller standby systems have used sealed VRLA batteries, while larger double-conversion systems have typically relied on flooded-cell VLA batteries.

There’s also a relative newcomer to the family, as lithium-ion has joined the two decades-old siblings. Here, we break down the UPS battery family tree:

1. Valve Regulated Lead Acid (VRLA). Commonly referred to as sealed lead-acid (SLA) or maintenance-free, VRLA batteries are the most common type of UPS battery.

Lower upfront costs, relative safety, easy availability and minimal maintenance are the primary advantages of this battery. However, deeming VRLA batteries “maintenance-free” is slightly inaccurate, as they still require regular cleaning and testing.

On the downside, sealed batteries have a short lifespan of about 3 to 7 years. The term ‘valve regulated’ represents the manner in which gas is released from a VRLA battery; if pressure becomes too great, a valve will vent the gas.

Because heat is detrimental to this type of battery, their optimal environment is a dry, temperature-controlled area of 77 degrees or lower.

It is important to note that since water cannot be added to most VRLA batteries, anything that increases the rate of evaporation or water loss — such as temperature or heat from the charging current — will subsequently reduce the life of the battery.

a. Absorbent glass mat (AGM). AGM batteries are a subtype of VRLA batteries. In AGM batteries the electrolyte is held in woven glass fiber mats.
This design allows for flexibility of design, improved self-discharge rates, and a wider operational temperature range.
b. Gel Cell. The second VRLA subtype. Originally conceived during the early 1930s for use in portable electronics early gel cells were less likely to leak when handled roughly.
A modern gel cell uses an electrolyte mixture usually comprised of sulfuric acid mixed with pyrogenic silica resulting in a gel like substance.
Gel cells are known for increased tolerance to vibration, as well as allowing for the lower cost 1-12 Amp hour range VRLA batteries found in smaller UPS systems.

2. Vented Lead Acid (VLA). Also known as flooded or wet cell batteries, VLA not only boast exceptional reliability, but an average lifespan of 20 years.

Composed of thick, lead-based plates flooded with electrolyte acid, these batteries typically have higher upfront costs than their VRLA counterparts, as well as pose a number of safety concerns.

As a result, they require regular maintenance and careful handling because their liquid is corrosive and can be set off by forceful movement.

Wet cell batteries should only be used in areas with proper ventilation and must be adequately protected against vibration and shaking due to the possibility of liquid spilling. In addition, they are prone to damage in extreme climates as the water inside can evaporate or freeze.

Even though wet cell batteries require more maintenance and are more expensive to replace, they are a highly reliable power source for double-conversion UPSs.

3. Lithium-ion. The new kid on the block when it comes to UPS applications, lithium-ion batteries have matured significantly in recent years, both in their design and range of potential uses.

Lithium-ion creates a safe and stable alternative battery option for UPSs, with benefits that include longer lifespan, weight reduction, smaller footprint and expanded warranty coverage.

While originally deployed as battery cabinets in three-phase UPS installations, there are now smaller single-phase lithium-powered UPSs on the market.

Although this type of battery tends to be more expensive than the other two options — which is expected to change as adoption rates become more widespread — lithium-ion batteries offer lower long term operational expenses since they last longer.

While each of the three types of UPS battery has its own set of advantages and disadvantages, it is important to understand your options — not to mention, how to best manage and maintain them.

One battery pitfall to avoid at all costs is thermal runaway, a topic we explored in our last blog.

UPS

5 Steps To Prevent Thermal Runaway

When it comes to ailments that affect batteries in uninterruptible power systems (UPS’s), few have the capacity to spark disaster like thermal runaway.

Occurring most often in valve-regulated lead acid (VRLA) batteries, this potentially hazardous condition is created when the rate of internal heat being generated exceeds the rate at which it can be expelled.

Ultimately, the increasing temperature dries out battery cells until the container softens, breaks and melts, triggering a range of possible catastrophes — from load failure and costly unplanned downtime to electrical fires, exploding batteries and the release of toxic chemicals.

Although thermal runaway clearly has the capacity to evolve into a true disaster, the good news is, it is unlikely to occur if just a few simple rules are followed.

Above all else, heed the old adage “an ounce of prevention is worth a pound of cure.” To that end, be sure to:

1. Keep cool — Because heat is one of the primary factors that leads to thermal runaway, it is critical to maintain the temperature of the battery environment at 77°F or below.

The second factor related to thermal runaway is the charge current. As the battery heats up, the internal resistance to the charging current is lowered, which allows more current and in turn, creates more heat.

Once thermal runaway begins, it cannot stop itself; the only cure is to remove and replace the batteries.

2. Trust the experts — Performing regularly scheduled preventative maintenance on the UPS and batteries in instrumental in avoiding thermal runaway.

During a PM visit, technicians can spot problematic batteries or cells before they fail, as well as adjust the charging voltage and current to ensure batteries are not overcharged.

In addition, while VRLA batteries are often deemed “maintenance-free,” they still require regular cleaning, checking and testing by trained professionals.

Need help deciding on a UPS? Get a free site assessment!

Click above to get started or call 240.772.1710 for instant help.

3. Replace the batteries — Some VRLA batteries may be pro-rated up to 10 years, but in reality, their average life expectancy generally falls between 5 to 7 years.

All UPS batteries have a rated capacity that is based on specified conditions, and any variation from these guidelines can alter the battery’s performance, shorten its expected life and lead to conditions such as thermal runaway.

To be safe, experts recommend replacing batteries when they reach 5 years.

4. Monitor your environment — Although battery monitoring systems have historically been more prevalent in higher cost, wet-cell installations, the fact is, thermal runaway is more common in VRLA battery strings.

With an array of offerings available for lead-acid battery applications, a monitoring system will record the voltage and temperature of every jar, saving data so it can be reviewed to establish trends.

A monitoring system can also identify if a particular jar has abnormal conditions, enabling it to be isolated and replaced long before thermal runaway has the chance to rear its ugly head.

Laboratory tests by battery vendors have shown that it takes hours or days for thermal runaway to be self-sustaining.

5. Be aware — While routine service calls, regular battery replacement and a monitoring system go a long way toward avoiding thermal runaway, don’t forget the value of simply keeping your eyes open and ears on the ground.

Visually inspect batteries for signs of corrosion or other defects, and keep your ears pealed for any unusual rattling or other sounds coming from the UPS.

By adhering to these simple guidelines, you can significantly reduce the likelihood of thermal runaway running away with your critical load!

Still have questions? Get a response immediately.

Click above to get started or call 240.772.1710 for instant help.

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