The intention of this article is to inform you of the basic principles and building blocks of an uninterruptible power supply (UPS) and what it does to offer you backup power when the mains fails.

Why is UPS backup power protection, like Riello UPS from Standby Systems, so essential in South Africa?

The power grid in South Africa, which has been failing for over a decade, has meant that power dips, surges, brownouts, and blackouts, including the very common rolling blackouts we have all become used to in daily life, are a common topic of discussion. Also frequently sought after are reliable sources of power backup during these outages to aid in the protection of your critical and sensitive loads because of all the bad power they are being subjected to from the mains grid.

The most common form of backup power that is affordable for both business and personal use is a Riello AROS uninterruptible power supply or UPS system with a home inverter battery backup solution. They work reliably to support your essential electronic loads, and they use ELITE, high rate, or cyclic lead-carbon UPS batteries, which are easily recyclable locally.

A Riello UPS can either be used for short power bridges to prevent the load from being dropped during the changeover while the backup generator starts up. Usually, when the mains fails, the generator will be off, so the load would lose power without the intervention of the UPS battery backup, which keeps the load powered.

Once the generator is running, it will supply power to the load via the UPS. This will ensure that the power to the load, whether generator or mains, is clean and within equipment specification. The Riello unit will go as far as sacrificing damage to itself to prevent the very precious emergency load it is supplying from being damaged by bad power from the supply.

Why do you need to protect your load from bad power supply?

No one should take the chance and let their IT, Data centre, electronics, or any other critical load that relies on power from the grid, operate while being subjected to supply variations that will damage hardware and corrupt software operations.

Some possible causes of these problems occur, but are not limited to, the following:

• Very short power breaks

An instantaneous power loss of a thousandth of a second can easily damage IT equipment and sensitive electronic loads without even making the lights flicker. These brownouts, as they are commonly called, are easily prevented by installing a UPS between the ESKOM supply and the critical loads.

Usually, these breaks are so brief that the UPS backup battery doesn’t even have to work; rather, reserve power within the power electronic circuitry prevents the load from being affected.

The amount of equipment failure resulting from these brownouts is vast. It costs the South African economy millions each year in equipment damage and software corruption, never mind the loss of productive time.

• Grid supply voltage fluctuation

Due to the overloaded, unreliable, and ancient power supply generation and its transmission grid here in SA, the voltage supply to your devices will vary greatly during the course of the day, depending on how strained the grid is at any one moment. Most electronic and IT devices will handle power variations of 220 VAC +/- 10% easily; however, it is not uncommon to find grid supply at +/1 20% or even 50%. When this occurs, the equipment running on it suffers severe damage, which, in most cases, is not noticed instantaneously, but over time IT and electronic equipment are gradually damaged irreversibly, resulting in service-life expectancies that can be reduced by as much as 80%.

A Riello UPS, on the other hand, will prevent anything mains supply throws at it from getting to its inverter critical load and can handle input supply variations by up to 40% in some ranges without needing to use battery power to keep its output constant at a varying percentage of full inverter load.

The ongoing grid supply deterioration is ever-increasing
The complete power supply grid failure and meltdown is growing. All electronic and IT loads, in fact, any load using electricity, is suffering 24/7 invisible damage as a result thereof. Modern electrics are extremely small, compact, and highly efficient, but along with this comes their susceptibility to damage by bad power and more exacting power demand in terms of availability and variance of supply.
The only way to prevent power damage to your electronic and IT equipment is to let a UPS or inverter intervene and keep the voltage supply to your load constant at all times, whether the mains supply is on or not.

• Automatic Voltage regulators and surge suppressors are not sufficient

These devices will protect loads under some conditions but not all. Neither of them can make/generate power when the mains supply is off. Although a UPS is not a lightning arrestor, it will sacrifice itself before the load if it can under the circumstances. UPS systems are relatively cheap by comparison to sensitive electronic equipment and IT/Data centre loads.

• just a Genset is often not enough

A generator set will power a connected load for many hours if looked after, but it will not protect sensitive, and IT loads when power fails, nor when power returns. Under both conditions, the critical load will be dropped and subjected to power damage. Also, the quality of standby generators varies greatly, and the power quality they deliver varies accordingly. Gensets are also prone to massive voltage fluctuations in their outputs when large loads start up like air conditioning plants, for example, where inrush power is huge. This instantaneously drops the voltage output by as much as 30% or more.

On the other hand, a UPS system that is installed between the standby generator and the load will prevent the critical load from being affected in any way and ensure unhindered performance.

• Power uptime and reliability is the most essential thing in any industry or household in modern-day life

In years gone by, automation and IT infrastructure acted in a supporting role for any industry or process. With the evolution of technology in both hardware and software, the centre of any business or process in the modern environment is the IT component. As IT cannot operate without reliable power sources, it is a key component to ensure modern-day life works well.

• Power is essential but increasingly expensive

With the cost and demand for reliable power increasing exponentially, there is a need to save money by reducing losses and using power effectively and efficiently. As a UPS system is a key component to reliable power and critical load up time, efficiencies have become ever more important to drive power loss use while in operation.

So what is a UPS all about?

A UPS is a device that offers the user and the critical load two very important things:

A UPS keeps the inverter load up and running when the power fails with the option of long runtime with extended battery backup for several hours or short runtime with short battery backup just to enable the user to power down the load safely.
2 A UPS filters and cleans the power to the load to prevent the critical inverter load from being damaged by bad power.

So how many different UPS technologies are available?

Offline UPS systems
An offline UPS stays off while the mains supply is supplying the load. More well-known offline UPS models like the Riello IPlug and IDialog ranges are only available in the entry-level end of the UPS market from 400 VA to 1600 VA. They sometimes include a voltage regulator to protect the load under normal mains variations and are not always pure sine wave UPS’s. They are what is called ‘Modified Sine Wave,’ which resembles a square wave somewhat, thus making this technology undesirable for certain loads like motors. It works with an average desktop PC or Laptop for short battery backup time, allowing the user to shut down the load. Because they are off all the time, they have a switch-on time when the power fails, and although this is only milliseconds, certain sensitive loads will not work with this technology. This is the cheapest UPS technology available but not suitable for high-end devices.
Line-interactive UPS systems
A line-interactive UPS is on all the time. The inverter senses the mains supply, and under normal operation, the load is supplied by the mains power. More well-known models of line interactive UPS like the Riello Netpower, Vision, Vision rack, and Vision dual between 600 VA to 3000 VA normally include a more complicated automatic voltage regulator (AVR) and filtering circuits of varying levels.
This also depends on the product to ensure a better quality of mains supply to the load. As the inverter is always on, the switching time between the mains supply and the inverter when the power supply fails or goes out of set tolerance levels that would otherwise damage the critical load is much shorter than the offline technology. Although relatively cheap, this technology is either a modified sine wave or pure sine wave and is more expensive than the offline UPS technology, but still fairly cheap.
NOTE: Both offline and line-interactive UPS systems are also referred to as single-conversion UPS technologies as they do not work like the online double-conversion technology UPS.
Online double-conversion UPS system technology,
Online double-conversion technology UPS systems consist of a rectifier, which supplies battery power to the battery and simultaneously to the inverter input. The inverter is on all the time, and the re-created sinewave of the inverter feeds the critical load with clean, pure Sinewave power, under all conditions, like bad grid power supply or power failures. This will ensure optimal operation of highly sensitive loads like computers and sensitive IT / Datacentre UPS, heavy industry, medical systems, etc. Because all components operate all the time, it is always online. The power flow to the load firstly goes through the rectifier to make DC battery power and then secondly through the inverter to make AC load power. It has two conversion processes hence the term online double-conversion UPS system.

Online double-conversion UPS systems offer the load the best protection available and are generally all pure sinewave units and thus suitable for any type of load application if they are sized right. High-quality units such a Riello UPS systems are available in sizes from 700 VA up to 20 kW single phase. Most are scalable to allow for modular addition of the same size unit in parallel or parallel redundant UPS configurations to cater for load growth and or redundancy in the UPS power supply to the critical load.

Single module three-phase versions of online double-conversion UPS systems are also available from 10 kW to 800 kW with scalability. Additional modular units are available as per above for all ranges within the Riello arsenal and allow for UPS plants of 6.4 megawatts for large data centres or centralized power plants.

They are also available with various modes of operation with up to 99% efficiency; for more information, visit Standbysytems or Riello Ups.

How do I know which is the right UPS technology choice for my needs?

To help you choose the right UPS, several factors need to be taken into consideration:

UPS technology and type of operation, which one?

The first question you need to ask yourself is, do you need an offline UPS, a line-interactive UPS, or an online double-conversion UPS?

There are many answers, but budget and affordability usually have a big influence here. If budget is of no consequence, then the online double-conversion UPS units are the ones you should consider.

However, if affordability is a big thing, then general loads such as laptops, cell phone chargers, and Wi-Fi routers will work fine with a good offline technology UPS like Riello or Pureline Brands.

For more sensitive loads like some high-tech flat screens and sensitive electronics, where budget is still a consideration, it would be best to select one of the following. A high-end line-interactive solution like Riello, and alternatively the least budget-oriented but still good quality Pureline PLLI ranges from Standby Systems.

Ultimately your target should be the online double-conversion UPS system solution; it is the best you can get.

How many phases UPS do you need?

Generally, all IT And Datacentre UPS loads are single phase. However, above power ratings of 20 kW, it becomes technically challenging to have a single phase output UPS and is uneconomical for electrical wiring and distribution. Generally, 3-phase is the best choice from 10 kVA upwards.

Industrial, medical, and other process UPS loads often have equipment that needs a 3-phase supply. If the equipment requires a 3-phase power supply, then your emergency power UPS you select must also be a 3-phase unit.

Generally speaking, though, most household, small office, and small UPS applications are single-phase, which is more cost-effective than a 3-phase uninterruptible power supply system below 10 kVA.

How do I work out the VA rating of the UPS I need?

Many factors influence UPS sizing. These include some common factors such as the type of load connected to the UPS inverter, inrush or start-up power, especially for motors, air conditioners, laser printers, start-stop loads industrial, commercial, IT or home use, and many others.

For complicated building loads, processes, medical, IT, Telecoms, transport, and Datacentres, it is best to contact Standby Systems to assist you with a proper sizing solution. For smaller applications, request a UPS sizing calculator to assist you in selecting the load that you want on your UPS.

Make sure with any UPS load calculation to allow for future load growth. Select a modular product such as Riello, where UPS modules can be added as your UPS power consumption needs grow.

It is always good to allow 15 to 20% on top of your sizing calculation for a safety factor to ensure your UPS works trouble-free.

Do I need a rack or tower UPS?

There is no difference in the performance and internal components between a rack and tower UPS. In fact, many single-phase market UPS units nowadays are rack or tower design in the same casing, also called an RT UPS.

Generally, if your equipment requires UPS backup and is rack-mounted, you can put the UPS in the same rack; however, many people prefer to keep the UPS separate from the loads, so the UPS does not add to the heat load of the IT equipment room.

What battery back up time or run time do I need?

Generally speaking, a UPS system is intended for battery backup times of up to 60 minutes. However, due to the power crisis, they are being used more commonly to supply longer backup times of 4, 6, or 8 hours of standby.

Theoretically, any battery backup time is possible, but the cost increases exponentially as the time gets longer.

If you want a UPS to give you clean filtered power and sufficient time to shut down your loads in an orderly and controlled manner when the power fails, you will need the following. It will either be manually or by monitoring and shutdown software like the Riello watch and save software which uses a UPS network interfaces such as SNMP version3, Modbus, or Jbus, etc. Then an inverter with a battery backup of 5 to 15 minutes is generally more than sufficient.

If you have a standby generator set in your emergency power arsenal, then only minimum backup time is required. If fitted with an automatic mains fail panel (AMF), the generator should start and take the load, i.e., feed the UPS input in under 60 seconds. If the generator provided has fuel and is regularly serviced will run pretty much forever non-stop. In this case, a minimum backup is usually chosen, but many UPS users prefer to rather opt for 20 to 30 minutes backup time to allow time to start the generator manually should its auto start not work. If required, this will also give enough time to shut down the inverter load without dropping power and damaging it.

Battery backup times in excess of 4 hours are becoming increasingly sought after but also comes with a whole lot of additional requirements. If they are intended for use during daily rolling blackouts, i.e., 4-hour discharge every 20 hours, this includes:

A cyclic application for load shedding – determine the battery cycle and how many cycles
Depth of discharge during each cycle
Battery manufacturers limitations on recharge voltage and current
Recharge ability of the UPS rectifier
Partial state of charge/discharge
Recyclability and how green is the battery you use

Cyclic battery operation during load shedding?

Most UPS applications are a float application for an occasional discharge once a month or less. Suppose a battery is to be subjected to a cyclic operation, i.e., 4 hours discharge every 20 hours. In that case, this is known as a cyclic application, with a whole new set of sizing and application rules being needed to ensure the system works like it is intended to. This also comes with a huge cost implication to be done properly.

Depth of discharge and application sizing?

If a battery is to be subjected to everyday discharges, it is very important to make allowance for this in the initial battery sizing for your UPS. For a cyclic operation of 4 hours every day, you do not want to remove more than 30% of the battery’s total capacity, or it will not be able to recharge fully within the next 20 hours. This results in a roll-on effect if not sized properly, that the battery every day gives less and less backup at the same load with people blaming the battery and not the person who calculated the sizing.

Additional to the depth of discharge of the backup battery or DOD, as it is known, is the cycling ability of the battery. Generally, normal lead-acid UPS and general-purpose batteries are very limited to the number of DOD with less than about 1000 cycles at 30% DOD and 300 at 100%. This means replacing the battery is going to be necessary every 2 to 3 years which makes the total cost of UPS ownership very high. Remember, a battery is a consumable item; every time it is used for emergency power backup, a portion of it is used up.

Battery rechargeability in 20 hours?

A normal lead-acid battery product is very limited with regard to rechargeability. Manufacturers specify a recharge current under cyclic applications of no more than 20% of the ampere-hour (AH) rating, or the battery will be permanently damaged. Under float conditions, this is even less at 10%. Generally speaking, normal lead-acid products will not achieve a full recharge in 20 hours; however, there are some exceptions, like the lead-carbon and thin plate pure lead battery technologies.

Lead carbon battery technology is particularly suited to cyclic use with over 7000 cycles at 30% (DOD) and battery current recharge limit a whopping 40% of AH. Lead carbon batteries are also very resistant to PSOC discharge, making them a unique lead-acid battery for use in cyclic applications of rolling blackouts or even solar.

Recharge ability of the UPS rectifier?

Many UPS systems are incapable of supplying sufficient recharge current, in particular on a cyclic battery application. Any battery is only good and reliable if it is sized properly for its application, i.e., float or cyclic. However, what is often overlooked is the rechargeability of the rectifier. As mentioned already, a lead-carbon battery can charge at 40% of AH rating, so a 100AH can recharge at 40 amps, but the question is can the UPS rectifier deliver the 40 amps? Suppose the UPS rectifier is not large enough to deliver the recharge power. In that case, it’s as good as using the wrong battery – neither is the batteries’ fault, but rather the fault of the person doing the calculations.

Partial state of charge-discharge or PSOC discharge

If a normal lead-acid UPS battery is subjected to a PSCO discharge, it will cause the battery plates to sulphate. Sulphating reduces the battery’s ability to perform, so a new battery can “fail” within a few months or even days if being subjected to this. However, a lead Carbon battery like the ELITE ELC series of sealed valve regulated batteries is very resistant to PSOC discharge.

Recyclability

Any lead-acid battery product is easily recycled in Africa, as lead is a valuable commodity. At the end of the life of a UPS battery, the battery has scrap value. However, the same cannot be said for the Lithium-ion and Lithium Iron Phosphate LiFePHO4. They require hazardous packaging and hazardous container shipment back to a recycling plant on another continent at a very high cost to the end-user. In Africa currently, these products are definitely not green, nor do they give money back to the user at the end of their life. On the contrary, it costs as much to send them back overseas as it does to buy a new one. So doubling your initial purchase cost will give you an estimation of what the actual total cost of ownership is.

What is the actual true power rating of the UPS inverter?

When buying a UPS, ensure you know the wattage rating of the inverter. A supplier of a 1000 VA UPS may look affordable but, if it is only a 600-watt unit, and another supplier has a 1000 VA, 800-watt unit that is more expensive, then the lower wattage is the reason for the cheaper unit with the same VA rating. VA ratings and power factor can be used to trick the UPS buyer into thinking a cheaper model is the same size, but it’s the watts that you need to compare.

Does the company I’m looking to buy from have the support and infrastructure I need?

When buying a UPS, it is important to look at the support and infrastructure behind the company you are buying from. If your UPS breaks, you need it fixed and as quickly as possible. Ensure that your supplier has a dedicated team of service engineers available 24/7 that are all factory trained. The support team from Standby Systems have all been trained at the Riello factory in Milan, Italy. Ensure that the UPS supplier has all the spare parts needed ex-stores, not ex-works, which will have to come from overseas and, therefore, have a long delivery time.

Does the UPS I am considering have a battery care system?

Although a UPS is the heart of your backup power supply in emergencies and provides your connected inverter loads with clean and filtered power all the time, it is useless without the associated battery backup when it comes to power outages. All modern UPS systems, therefore, come with highly advanced built-in battery care and management systems. This system ensures the battery is maintained in an optimal condition at all times and doesn’t cost much more than a UPS without these functions. A battery is the heart of your UPS, so rather opt for a UPS with battery care and management built into it.

What software and control is available for the UPS I want, and do I need it?

There are many monitoring and control software packages available for UPS systems allowing remote control, fault reporting, and UPS system management, as well as the orderly shutdown of loads during a power failure if a generator backup is not available or when the UPS battery starts to go flat. Watch-and-save software from RIELLO UPS is a good example of a high-end product, and is available for free with any purchase of a Riello UPS. It can be used in conjunction with the slot in the network card in the rear of the RIELLO UPS for SNMP, MODBUS, JBUS ETC.

This software allows the user to:

Manage and control the UPS within the network locally or remotely
Immediately receive alarm notifications on a real-time basis
Provide automatic or manual remote shutdown of non-critical loads to conserve battery
Shutdown critical loads in an orderly manner if the battery is flat
Partial state of charge/discharge
Perform detailed analysis of your UPS plant and event history at your fingertips

Do I need a stand-alone or parallel redundant UPS?

For smaller UPS applications like a small office or home use, it is normal to use a single-phase UPS. However, it may be necessary for larger applications to consider a parallel UPS plant to achieve the N-load or redundancy of N+1 or N+2, as used in some critical applications. Paralleling ability is to be considered necessary if you expect your current UPS load size to grow in the future as your business grows.

What is the warranty on the equipment I’m looking at

Warranties on a UPS system and batteries are generally 12 months ex-works for plug-and-play applications or on-site for wired installations. Some UPS manufacturers like Riello UPS offer warranties of up to 5 years on all 3-phase UPS systems and some selected single-phase UPS systems. Certain batteries like ELITE TPPL are also available with up to a 3-year warranty option.

Do I need a Generator in conjunction with my UPS or not?

In South Africa, nowadays, with the ever-failing power grid, it has become common for substations to burn down and the distribution of power drastically interrupted to large areas for sometimes weeks on time, because of cable theft or no maintenance having been done. If such a situation occurs, the question is, can you live without power, and what will it cost your business in lost revenue? A battery backup has only a finite time, after which your UPS will shut down, and the load will be disconnected. Loss in revenue and productivity should be the deciding factor when buying a generator or not.

Take note
In today’s business world, huge monetary investment is put into IT infrastructure on an exponential basis every year as businesses become more reliant on IT and artificial intelligence in modern-day life. To keep this all operating properly, power reliability and cleanliness are increasingly critical, with modern IT loads having tighter tolerances regarding power supply than ever before.

Modern UPS systems have evolved to keep up with these new un-precedent high standards of power backup and filtering requirements. They have become an essential component in any IT infrastructure. Along with the efficient use and minimum power losses, any UPS user needs to be aware of all the factors that can (and do) affect your UPS.

Who is Standby Systems and Riello UPS?

Standby Systems was formed with its head office and factory in Laserpark, Honeydew, Johannesburg, in 2003 by Greg Bennet. The head office is in Milan, Italy. We have the sole distributor partnership of AROS UPS systems, now known as Riello UPS or, more commonly in Southern Africa, as AROS RIELLO UPS SRL, the 5th biggest manufacturer in the world.

Riello UPS systems are one hundred percent Italian designed, built, and tested above 4 kVA. With this high-quality UPS product range Riello UPS has, over the last 15 years, built itself up to become a worldwide UPS market leader as the fifth biggest manufacturer of UPS systems in the world.

Over the last 18 years, Standby Systems has grown into a Southern African first choice for the Riello UPS brand with countrywide coverage and 24/7 support at all major centres.

Standby Systems specialises solely in the art of UPS systems. It is a technically strong company with over 250 years of UPS technical expertise within our structure. It is a fully-fledged company consisting of over 30 employees countrywide. They have in-house testing and repairs of UPS systems down to component level, qualified technical UPS sales engineers, documented SHE and quality systems in line with ISO 9001 requirements, and full logistics support with crane trucks and complicated rigging equipment. We use red seal UPS riggers, including ex stock warehousing of RIELLO and Pureline UPS systems and ELITE high rate and cycling batteries, full UPS project management for any type of construction contract from JBCC to FIDCI, and many others, in house CAD facilities and design. A solid service and maintenance division of over 15 people countrywide, with a Riello UPS, spares department no other UPS company in South Africa can beat.

For further information, where do I go?

Click here for white papers on UPS topics.

Written by Greg Bennett, Managing Director, shareholder, and founding member of Standby Systems since start of trade in 2003. As the sole distributor for world-renowned and 5th largest uninterruptible power supply ( UPS ) manufacturer, formerly AROS and now Riello SRL 100% designed and built in Italy, in all regions of Southern Africa except UPS in Natal and UPS in West Cape.

Greg holds the technical qualifications of ND, NHD electrical engineering Technikon Witwatersrand in electrical engineering heavy current. He started as a successful bursary applicant with Siemens UPS. He has worked in all areas of UPS industries both nationally, including heading UPS production, UPS technical sales and project management, design, etc. He has offshore experience in UPS in both China for UPS production, sales, and distribution, and in Germany for international technical sales and support, while working for Siemens UPS from 1989 to 1999. After that, Greg returned to South Africa, where he remains active in the UPS industry.

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Why is UPS backup power protection, like Riello UPS from Standby Systems, so essential in South Africa?