Quality control of the electricity supply

Sine Wave Scope Trace

This is a guest post by Werner Karau of Antares Power,  Power Inspired Distributor in Germany.

In this edition we consider the quality control of electricity supply.

May we invite you to a small thought experiment?

How do you answer this question: “Would you drive your car without fuel filter?”

“No, of course not“, you would probably reply. jerry-can

Gasoline or diesel fuel is needed to operate the engine. Okay, this is no breakthrough insight. Oil companies provide the quality of fuel in accordance with European standards. After delivery to the petrol station network they are no longer responsible for contaminants until use in your engine. The fuel is filtered before use by the engine of your car. The filters are regularly renewed so that your engine always receives clean and suitable fuel.

Without this filter foreign material can enter the circulation and cause malfunctions in the form of motor standstill, dropouts, reduced power, also accelerated wear, or in extreme cases even destruction and major engine damage.

It is self-evident to have these filters and to look after them.

Now we apply this model on the power, the fuel in form of electrical energy that powers your systems. Electrical energy is an unusual commodity. It is continuously needed, cannot be stored in significant quantities and is beyond quality control before use.

Before installation of complex systems it is sometimes quoted which sockets are to be used with which voltages, frequencies and circuit breakers. That was it mostly. Rarely references to preferred power grid systems such as the TN-S system with better EMC characteristics.

Practically all your systems are “somehow” connected to the existing power grid. An examination of the suitability for the operation of your systems will not take place. cable jumble

Basically, your system matches the high-performance engine of a luxury car, which is being used without a fuel filter. It has been developed with all of your expertise, continuously improved and manufactured under the highest quality standards to be now driven with dirty energy.

Some argue that all this is only the problem of the user. We cannot answer this question, however, but see the results in practice.

– Do you know the quality of the electricity at the installation site?

– Or does your customer, which is the user, know the state?

If your system has operating faults or disruptions, which appear suddenly and are inexplicable, components have a premature wear / failure or the unit is even destroyed, the user first seeks for the fault in the system itself.

Noisy Scope Trace Your “workshop team” will be sent to fix the error. If the cause is not to be assigned to an application error, components need to be replaced during the warranty period, so the costs can’t be billed to the user neither. When in doubt, ex gratia payments are to be made. Often the costs are agreed in the context of a maintenance contract.

The power companies cannot be held responsible for it, they guarantee for the security of supply to the delivery point up to a certain degree but not for the quality – especially since most interferences are “home-made” through the user.

Your system meets all the current standards and guidelines for the CE mark. Here, the electromagnetic compatibility, the emission and immunity has been checked. However, these tests will be held under standardized conditions in the test laboratory, real conditions cannot be simulated. Other devices of any manufacturer can be found in the immediate vicinity at each installation site. All are connected to one and the same power grid and some of them are connected via data cable.

Each unit carries the CE mark. It is simply not possible to examine any of these combinations in terms of interference in EMC laboratory. Influences are predetermined. It does not affect every single device. A heating plate is insensitive when compared to systems with sensors that measure electron volt range. The more powerful, precise and highly technical installations are, the higher the clock speed of data processing digital technology (CPU, memory), the lower the flanks of the logical ones and zeros, the more sensitive they react to the slightest disturbance of the power supply.

At this point it is difficult to find a connection with the supply voltage. Some systems are unaffected, others do not tolerate interference. Often service technicians quote our customers: “But the other device always works…“.

Most everything results in a situation, which is not satisfying for everybody involved.

The user receives repairs or services. Why should he make an effort in causal research?

There are almost always the service managers and service technicians of our OEM customers, who request our services.  power quality monitoring

An analysis of power quality creates clarity. We offer you this service for free. The process is very simple. The installation and start-up of our measuring instruments can be handled by anyone. The data acquisition is fully automatic and after an agreed recording time you will send us back the devices for evaluation. You will receive a comprehensive report. Whether before installation or for supportive investigation of an incident.

We often hear from our customers that our analysis has been the basis for a lasting solution to the problem. It is also the basis for deciding whether the user solves the problem or the manufacturer of the systems. For us, the analysis allows the selection of a suitable system to ensure power quality. Everyone involved benefits from it.

Power Quality ReportsUse our service to reduce the number of ex gratia payments or warranty claims in your workshop in order to create more capacity for your customers who come to billable inspections. Less unnecessary service calls, caused by electricity allows more efficiency and increase profit from maintenance contracts.

We have top manufacturers of industrial systems as partners for our solutions aside. When selecting we focus on meeting the industry-specific specifications, e.g. suitability for extreme dynamic loads, overload capability, robustness, etc. The straightforward way to our partners enables us in addition to the direct support also being able to offer an excellent price-performance ratio.

We follow this principle with suitable, compact, appropriately sized and cost-effective solutions, at the point where the power is needed to prepare optimally suitable power quality for your system.

Have a pleasant trip” Yours Antares Power Solutions Team!

Sine Wave Scope Trace

Natural Disaster Survival Kit

natural disaster survival kit

Severe weather conditions and natural disasters are more of a threat in certain geographical areas than others. You need to be prepared if you live in a high risk area. It is recommended that you have an Emergency Supply Kit ready for when severe weather strikes.
A separate kit for home, work and for your vehicle is a good idea

Priority items are:


1. Water and food

tinned food You should have sufficient supplies of water and long-life foods. Stock 4 litres of water per person per day with supplies for three days for evacuation. You should hold 2 week worth of supplies at home and sufficient amount of food for the same period of time. Don’t forget to have the appropriate supply of pet food and of course water is also essential.



2. Important medications

You should have at least one week’s supply of prescription medications and common meditations such as pain killers, antiacids etc. Your survival kit should also include a first-aid kit.



3. Documents

important documents
You should have copies of personal documents including birth certificates, passports, medication lists, medical records, insurance and bank policies etc. in a waterproof container ready to be taken with you during evacuation.




4. Personal hygiene items

including soap, tooth brushes and toothpaste, towels, deodorant and other essential items.






5. Electronicsmobile

Your emergency supply kit should also include your mobile phone, chargers, battery backup, battery-powered radio, extra batteries and a contingency power supply solution for operating any medical equipment that is used regularly.




6. Cash.cash







7. Other essentialsflashlight

Blankets, flashlight & spare batteries, multipurpose tools and maps should also be included in your emergency supply kits.





You may also want to include:

  1. Whistle, dust mask, glasses and contact lenses
  2. Sleeping bags for each person
  3. Paper plates, cups, plastic containers
  4. Water cleansing drops, matches
  5. Fire extinguisher
  6. Spare clothes and sturdy shoes
  7. Baby formula, nappies, bottles etc.


When a disaster strikes it is never pleasant but with the emergency supply kit you will feel more comfortable and at ease knowing you are prepared for any scenario.

Top 5 interesting facts about UPS

Facts about Uninterruptible Power Supply

You probably know how Uninterruptible Power Supplies work and what their purpose is, but we have the top 5 interesting facts about UPSs that you probably didn’t know!


UPS facts - UPS inventor

The history of Uninterruptible Power Supplies is somewhat a mystery – nobody can name one person or one date when UPSs systems were invented. There were many theorists and scientists involved in research and studies, however nobody  can claim to be the inventor of UPS.



UPS facts - ups patent
source: google/patents

This rather amusing acronym stands for “Apparatus for Maintaining an Unfailing and Uninterrupted Supply of Electrical Energy”, which is a first ever UPS patented in 1934 by John J. Hanley. Mr. Hanley mentions in the document that the invention is to be used with fire alarms and other safety systems to protect properties and lives. It is amazing how far UPSs have come since then and how the variety of applications widened since 1930s. The AMUUSEE was an ancestor of UPSs as we know them now. We are certainly grateful that UPSs are now called Uninterruptible Power Supply rather than the tongue twister that is used to be back in the day.

You can read the whole patent document at google/patents.


UPS facts - largest ups in the world
source: newsminer.com

The largest Uninterruptible Power Supply system in the world is a 46-megawatt system in Alaska.  The system is called the “Battery Electric Storage System (BESS)” and is located in Fairbanks, Alaska where it powers the entire town! It can provide up to 15 minutes runtime at 26 megawatts, providing enough backup power until the generator comes on. The runtime is achieved by four battery strings, each containing 344 series of connected battery modules. That is one truly amazing UPS.


UPS facts - batteryA UPS is nothing without batteries. Did you know that majority of faults within UPSs are related to batteries? Good batteries matter and so to ensure your UPS provides maximum reliability, you need to organise for appropriate maintenance. Power Inspired Uninterruptible Power Supply systems come with VRLA batteries with 3-5 year design. This time is however approximate and depends upon many factors, including the environment in which the UPS is stored. You can see how to prevent premature battery failure in our previous blog.



UPS facts - TX Series Isolated UPS SystemsPower Inspired’s TX series provides unique safe UPS technology. The units contain an isolation transformer which protects from electric shock and ensures the UPS is isolated and safe. TX series units range between 1KVA – 10KVA, they have a small footprint and the design is highly modern and minimalistic. The larger units (3KVA, 6KVA and 10KVA) also come with wheels for ease of installation. TX series UPS are designed to provide highest degrees of power protection for laboratory, industrial and medical applications. More information about TX series can be found here.

UPS ECO mode – what’s so good about it?

UPS eco mode

All of our online double conversion UPS systems feature a setting option to run the UPS in an ECO mode. What does this mean? And is it beneficial for you? We will try to answer those questions for you.

An ECO mode in UPS systems essentially means that the UPS’s inverter is in a standby mode. It only kicks in if the mains power fails. By enabling ECO mode on your UPS it will basically have the same operation as a regular line interactive UPS.  In a nutshell, by enabling the ECO mode you’ll expose the load to raw utility power.

What’s good about it?

The ECO mode has some great advantages, such as efficiency improved from 94%-97% to 98%-99% and lower operation costs (up to 4% reduction on energy use). It may also prolong the lifetime of some of the UPS components due to the decreased operating temperature on these components – the UPS is in a bypass mode hence some components are not in use which may prolong their life span.

What’s bad about it?

However the ECO mode not only has positives, it also comes with some risks: the fact that the UPS must first detect power failure and then turn on the inverter results in a transfer time that in some critical applications cannot be tolerated. Unlike the standard (online) mode of fully featured online UPS systems (our VFI-T, VFI-B and TX series) where the switchover time is nonexistent, this may be an issue for some critical, highly sensitive equipment. The ECO mode can improve UPS efficiency by about 2%-4%, however at the cost of possible downtime due to the switchover time. The switchover time can last anywhere from 1-16 milliseconds during which time your equipment will be exposed to any power problems present on the mains. Some equipment may be okay to cope with the transfer time, however some more complex and critical loads may be unable to tolerate it.

The ECO mode comes with some other risks: Besides the risk of reduced electrical protection which may have a negative impact on reliability and possible operation issues, the UPS in ECO mode will switch to battery at any instance of power problem which may have been easily dealt with without reverting to battery using standard online mode. This may negatively affects the battery’s lifetime and wear.


These are the advantages and disadvantages of using UPS in an ECO mode. The ECO mode can improve efficiency and reduce operation costs of your UPS, however while choosing your default operation mode, you need to bear in mind all the associated risk and decide if your equipment can take on the risk. As an operator you need to thoroughly consider all pros and cons and decide what settings will work best for you.

UPS Classification to EN62040-3

EN62040-3 UPS Classification Curves

EN62040 is the European Harmonised Standard for Uninterruptible Power Systems (UPS). Part 3 (EN62040-3), published in 2011 is the Method of specifying the performance and test requirements. Here we’re looking at UPS Classification which is at section 5.3.4 entitled “Performance Classification”.

UPS Classification

If you take a look around our product lines you will see UPS models beginning with such acronyms like VFI, VIX and VIS. Well, there’s more to them than appears at first glance, as these acronyms let you know at a glance what the UPS technology is. I say that, but it is not technically correct, as the standard specifically states that the classification is performance based and does not exclude any particular technology or topology.

The UPS Classification is of the following nomenclature and we’ll go through each part in turn:


AAA = Input  Dependency Characteristic

This part consists of 2 or 3 letters and describes the relationship between the UPS output and the UPS input during normal operation. Normal operation means mains power is present.

Three classifications are offered, VFD, VI and VFI. They are so designated depending whether or not the output (V)oltage and (F)requency  are (I)ndependent or (D)ependent on the input Voltage and Frequency.

VFD: Voltage & Frequency Dependent

UPS Classification. Voltage Frequency Dependent (VFD) Topology

This topology is also known as “offline”. In normal operation what is at the UPS AC input, is at the UPS AC output. Hence the UPS output is dependent on the input voltage and frequency.

If the mains should go out of tolerance the switch moves from AC input to the Inverter. This topology is the lowest cost of all UPS topologies and is almost certainly to have a square wave inverter. The switch does mean there is a slight break during the switch over.

VI: Voltage Independent (Frequency Dependent)

Voltage Independent UPS Topology

The VI topology is similar to VFD with the exception of the Buck and Boost Autoformer. This device allows the UPS Output to be lowered (“Bucked”) or raised (“Boosted). The advantage of this is to prevent needless battery operation for sustained over or under voltages. To that end, the output voltage is not directly dependent on the input voltage but it is either the same as, or a set percentage higher or lower. So IMHO, saying it is Independent is pushing it a little, but there does need to be a way of differentiating from offline units. The frequency of course is dependent.

Lower cost VI units will have a square wave inverter, much the same as offline units. Higher specified devices will have a sine wave inverter.

VFI: Voltage & Frequency Independent

Voltage Frequency Independent (VFI) Topology

VFI Technology is also known as Online Double Conversion, due to the fact the AC is converted to DC and then from DC to AC. In the much simplified diagram above the batteries and rectifier feed a common DC link. This DC link powers the inverter – which will practically always be a sine wave. The UPS AC Output is fed from the inverter. Thus the output voltage and frequency are truly independent. Note some units will in fact track the input frequency and are therefore not precisely independent, but the main point it is the inverter circuit that is the power source.

BB = Voltage Waveform Characteristic

This part of the UPS Classification determines if the output waveform is sinusoidal or not on both normal operation and battery operation. Normal operation is the first character and battery operation the second.

The character can be either one of “S”, “X” or “Y”, for linear and non-linear loads. A linear load is a resistive one, such as a heating element. The reference non-linear load is a smoothed bridge rectifier circuit. Note that in the definitions below, the output is considered sine if the Total Harmonic Distortion (THD) is under 8%.

“S”: The output is sine for both linear and non-linear loads.

“X”: The output is sine for linear load, but non-sine for non-linear loads.

“Y”: The output is non-sine for both linear and non-linear loads.

For example, a square wave offline UPS will be designated VFD – SY. The VFD is for Voltage Frequency Dependent, but since the output follows the input, then in normal mode the output will be as per the mains supply, eg a Sine. When on battery though the output is non-sine for both linear and non-linear loads.

Note, the nomenclature we use in our product range follows this only loosely. For example we use VIS and VIX to determine line interactive sine, and line interact non-sine. Just want to avoid any confusion.

CCC = Dynamic Output Performance

This is a 3 digit number.

The first digit refers to the voltage variation due to a change in operation mode e.g. from mains to battery.

The second digit refers to the voltage variation due to a step change in a connected linear load.

The third digit refers to the voltage variation due to a step change in a connected non-linear load.

Each digit is designated 1, 2 or 3 depending upon how the output voltage reacts according to the curves in the graph below.

EN62040-3 UPS Classification Curves

It looks complicated but not as bad as it looks. It also gives a very useful guide for knowing what UPS technology is required for your application. There are 3 curves in the chart with 2 limits, one for overvoltage and one for undervoltage.

Performance Level “1” is required by sensitive critical loads.

Performance Level “2”will be accepted by most critical loads.

Performance Level “3” will be accepted by most general purpose IT loads (eg switch mode power supplies).

For example a high quality online double conversion UPS (such as our VFI Range) will give 111 performance. Our VIX UPS Range range will be 321.


Just as an aside, this is my take on the standard and I’ve deliberately not copied any text verbatim or copied any diagrams from the standard for obvious reasons. You can buy the standard from the good old British Standards Institute: BS EN62040-3:2011. And you’d be better off becoming a member first.

AC ReGenerator Input Vs Output

What a great question received into technical support today:

Can you show the difference between the input and output voltage waveforms on the AC ReGenerator?

We have a bit of bespoke in-house test equipment that we use for looking at the quality of the mains supply. It allows us to view both normal and common mode noise levels, as well as viewing an AC power waveform. We can connect it to the output of the ReGenerator and show you a nice clean output waveform. We can also connect it to the input and show you another apparently clean input and output waveform, or a distorted waveform, or a clean high voltage waveform. The point is, the output of the ReGenerator is the same, regardless of the input waveform. If the input waveform is good, then this isn’t really showing us anything.

So what we have done is to create a secondary piece of test equipment that provides a distorted power waveform to the ReGenerator:

Distorted AC power waveform

This oscilloscope trace shows a pretty messed up AC power waveform, with a high Total Harmonic Distortion. Such a power waveform will cause untold problems with electronic systems, and with any inductive devices such as those containing transformers or motors. Any system requiring a quiet noise floor will be sadly disappointed as the noise levels will be remarkably high on the line to neutral. Any standard filter devices will redirect this to the earth resulting in common mode noise issues as well. Clearly not good for Audio Visual applications!


When we feed this power waveform into an AG500 ReGenerator, we get this at it’s output:

Power Inspired AG500 ReGenerator Output Waveform

See the harmonic distortion is eliminated! Not only protecting the inductive elements but ensuring that noise levels have improved dramatically. Exactly the sort of environment your AV equipment wants to see. This is the main difference between ReGenerators and filters. The ReGenerator recreates a new AC power waveform. A filter can only try to remove what shouldn’t be there.

Read more about the Power Inspired AG Series ReGenerators.

Buy online.

Transfer times in UPS – what are they and how will they affect my equipment?

Transfer time in UPS

UPS transfer time

“What is transfer time in UPS?”

The definition of transfer time, sometimes also called switchover time, says it is the amount of time a UPS will take to switch from utility to battery supply during a mains failure, or from battery to mains when normal power is restored. What this means is that when the main power supply fails, the UPS will need to switch to a battery mode to provide sufficient power and ensure smooth running of the attached equipment. The transfer time duration differs, depending upon the UPS system attached. It should, however, always be shorter than your equipment’s hold up time. Hold up time is the amount of time your equipment is able to maintain consistent output voltage during a mains power shortage.

Line interactive UPS systems, such as our VIX or VIS series, have transfer time typically between 2-6 milliseconds. For regular computer based systems, where hold up time is approx. 5 milliseconds, line interactive UPS systems are usually sufficient; however some computer systems, as well as other critical sensitive equipment, are more sensitive and require shorter transfer time. Hence in this case you should always choose UPS with zero transfer time like our VFI series.
If your equipment is critical and doesn’t tolerate even slightest power distortion, we recommend choosing online double conversion UPS technology with zero transfer time to ensure your equipment has the highest degree of protection.


Here’s a quick look up of transfer times for Power Inspired UPS systems:


Product UPS technology Typical transfer time
VIX3065 Line interactive UPS Typically 2-6 milliseconds
VIX1000N Line interactive UPS Typically 2-6 milliseconds
VIX2150 Line interactive UPS Typically 2-6 milliseconds
VIX2000N Line interactive UPS Typically 2-6 milliseconds
VIS1000B Line interactive UPS with sinewave inverter Typically 2-6 milliseconds
VIS2000B Line interactive UPS with sinewave inverter Typically 2-6 milliseconds
VFI1500B Online double conversion UPS Line to battery 0 milliseconds
Line to bypass Approx. 4 milliseconds
VFI3000B Online double conversion UPS Line to battery 0 milliseconds
Line to bypass Approx. 4 milliseconds
VFI3000BL Online double conversion UPS Line to battery* 0 milliseconds
Line to bypass Approx. 4 milliseconds
VFI6000BL Online double conversion UPS Line to battery* 0 milliseconds
Line to bypass Approx. 4 milliseconds
VFI10KBL Online double conversion UPS Line to battery* 0 milliseconds
Line to bypass Approx. 4 milliseconds
VFI1000T Online double conversion UPS Line to battery 0 milliseconds
Line to bypass Approx. 4 milliseconds
VFI3000T Online double conversion UPS Line to battery 0 milliseconds
Line to bypass Approx. 4 milliseconds
VFI10KT Online double conversion UPS Line to battery 0 milliseconds
Line to bypass Approx. 4 milliseconds
TX1K Online double conversion UPS with isolation transformer Line to battery 0 milliseconds
Inverter to bypass 4 milliseconds
Inverter to ECO Less than 10 milliseconds
TX3K Online double conversion UPS with isolation transformer Line to battery 0 milliseconds
Inverter to bypass 4 milliseconds
Inverter to ECO Less than 10 milliseconds
TX6K Online double conversion UPS with isolation transformer Line to battery 0 milliseconds
Inverter to bypass 4 milliseconds
Inverter to ECO Less than 10 milliseconds
TX10K Online double conversion UPS with isolation transformer Line to battery 0 milliseconds
Inverter to bypass 4 milliseconds
Inverter to ECO Less than 10 milliseconds

*unit doesn’t contain internal batteries, requires external battery pack/cabinet

Transfer times are dependent on which stage the power interruption occurs in. That’s why the transfer times stated in the above table are approximate.
As previously mentioned, transfer times also measure the amount of time it takes for the UPS to switch back to mains. The transfer back to mains power is always controlled with minimal interruption as this transfer is planned. As opposed to an unplanned mains failure which happens suddenly and hence a variation in the actual time taken.

transfer time

We have conducted a transfer time measurement using an oscilloscope (photograph above). For purpose of this exercise, we have used a standard line interactive UPS system and stimulated a power cut. The oscilloscope managed to capture the transfer time which on this occasion lasted 15 milliseconds, due to the original sine wave being interrupted at the peak of the cycle.

 “How does transfer time affect my equipment?”

That’s simple – if your equipments tolerance is below UPS transfer time, the UPS will not provide power in sufficient time in order to keep your equipment running.
Let’s say you have highly sensitive laboratory equipment with hold up time of 2 milliseconds. Line interactive UPS will not be sufficient in this case as it will not switch to battery mode quick enough. You will need to invest in an online double conversion UPS or Isolated online double conversion UPS in order to avoid any downtime. On the other hand if your equipment is a very basic computer workstation with approximate transfer time of 10 milliseconds, you can use the line interactive UPS system with peace of mind that your equipment is protected.

Transfer time is definitely one of the things you need to keep in mind while searching for suitable UPS. More factors affecting your choice of UPS technology are covered in this article.

How to save energy during Christmas season

How to save energy this Christmas

Energy saving during Christmas

With Christmas just around the corner, we thought it’s important to talk about energy usage during this jolly period. We all know that Christmas is the season of light, warmth and coziness. But with lots of Christmas lights comes the highly dreaded January energy bill. Here are some easy tips on how you can enjoy the Christmas magic without being out of pocket:

1. Choose LED Christmas lights 

Chrismas lights

source: christmaslightsetc.com

Invest in LED mini Christmas lights over regular ones to save on energy bills. LED lights use around 90% less electricity and cost nearly 6 times less to run than regular lights. They create the same magical atmosphere – and they also have a longer life span!

2. Don’t leave your Christmas tree lights on when you’re out

Christmas energy saving

A decorated and lit up Christmas tree is definitely one of the most beautiful things about Christmas. But is it necessary to leave the tree lights on even when you are out of house or overnight? Turn them off when you’re not in the room and save money.


3. Don’t leave electrical appliances in stand-by mode

Energy saving christmas

TV, Hi-Fi, game consoles, laptops and phone chargers… The list goes on and on. And during Christmas period we tend to use these appliances more than ever! Did you know that leaving chargers plugged in alone can cost you up to £60 a year! Unplug your chargers if not in use and switch off your TV when you’re not watching it – it can spare you quite a few pounds (well… at least those in your wallet).


4. Candles

Saving energy during Christmas

Candles can not only create beautiful atmosphere – they can also save a few pence on your winter electricity bills, if you use them as a light source during cold winter evenings. Just make sure you don’t leave them unattended.


5. Use one or the other

Christmas lights saving energy

Have you decorated your lounge with lots of Christmas lights? If your answer is yes, consider if you really need to turn the main lights on as well. Stick to one or the other and save some cash.


6. Wash your Christmas jumpers at 30 degrees

Saving electricity

Did you know that washing machines use 40% less energy when washing at 30 degrees than washing at higher temperatures? Keep that in mind next time you wash your warm sweaters and you could save on your electricity bills.


7. Keep the temperature down

saving energy during Christmas

With all those Christmas lights on, cooking, baking and people around, the heat will naturally increase in your home so no need to have the heating up too high. It can also save you a little bit of money on energy bills.


8. Energy efficient cooking

save money at christmas

Cooking, baking, frying, boiling… it all costs money in energy. And during Christmas, when food is everywhere you look, it is even more noticeable. Try to cut down on energy costs by placing multiple dishes in the oven at the same time, or using smaller appliances such as microwave for smaller cooking tasks. Keeping the lids on your cooking pots can also shorten the cooking time, hence lower energy usage.


9. Peace of mind


Enjoy the season of peace truly peacefully knowing that your crucial equipment is protected. Have a UPS system connected to any of your critical load. Don’t have a UPS yet? Our handy UPS calculator tool will help you determinate which UPS is most suitable for your equipment.

What is a negative 48Vdc system?

SmartSys Telecom Rectifier

In telecommunication systems it is common to have a supply voltage of -48Vdc. What this means is that the positive terminal is grounded. But why 48V and why ground the positive end? Surely it would be more intuitive to ground the negative end? I’ll answer these questions in turn.

Why 48Vdc?

This is a trade off between a voltage that is deemed to be safe and also suitable to deliver enough power through telecommunication cables. Modern standards eg BS EN 62368 refer to an absolute safe level of 60Vdc, and this has been the generally accepted level for decades. (Note, however that ELV, or Extra Low Voltage is classed as 50Vac, or 120Vdc). 48Vdc is also easy to obtain by stringing 4x12V batteries together to allow uninterrupted operation. With a float charge on the batteries the voltage on the network will be over 50V but under the 60V limit. Note that 5x12V batteries would give you 60V but the float charge would therefore need to be higher and would make the voltage unsafe.

But why not just use 12V?

For any given power, P, and since P=VI, I=P/V, the current required is inversely proportional to the voltage. Or, the higher the voltage, the less current is needed to deliver the same amount of power. This is important because the more current you require, the thicker cable you need. For example, if we had a load that required 480W, then a 48Vdc system would need 10A of current, whereas a 12V system would need 40A of current

The higher the current the larger the cable required.

A 10A cable would have a cross sectional area of 1mm2 (16 AWG), whereas a 40A cable would require 6mm2 (8 AWG). That’s six times more copper required for the same power delivery.


So the higher the voltage the better for the cost of the installation, but higher voltages mean more hazards and so the compromise is 48Vdc.

Why -48Vdc?

At first logic prevailed and the negative terminal was bonded to ground. This works indoors but the problem came with cables being used outdoors or subject to moisture.

What happens is basically electrolysis. With respect to ground potential, if the negative end is bonded this becomes an “anode” in electrolysis terms and this is the part of the system that basically gets dissolved. So early +48Vdc systems soon suffered from corrosion.

When the positive end is bonded then this becomes the “cathode” and is protected against corrosion. This is called cathodic protection, and is why the system is connected as it is today.

Why bond at all?

You could have the system effectively floating but then problems would occur when connecting to other systems, with the potential of very high voltages with respect to ground. By grounding all interconnected systems will be referenced to earth potential.


In short, 48Vdc is used as it is the highest safe voltage that can easily be obtained using batteries. Ground bonding is used to ensure all interconnected systems are referenced to the same potential. The positive end is bonded to protect against corrosion.

Check out the Power Inspired SmartSys – a highly configurable -48Vdc system.

Power Problems and How To Solve Them

How to deal with power problems / virus

Power Problems

Electricity is mainly generated by turning a large magnet through coils of wire. This induces a clean sinusoidal waveform that can be transmitted down cables, stepped up and down using transformers, to eventually find it’s way into our homes, offices and factories. Along the way, however, some power viruses can interfere with this clean power and cause your equipment power problems. Some problems are obvious, and others not so. There’s generally accepted to be 9 power problems but there’s another problem which is often overlooked and we make it 10.

1. The Blackout

This is one of the most obvious power problems. A complete loss of power. Caused by a variety of reasons, tripped breakers, fuses blown, faults on the utility line, the list goes on. Some power cuts are brief lasting only a moment, for example lightning striking a power line causing protection equipment to operate and then reset. Some may be for hours or days, for example when a cable is dug up by accident. Others last until the breaker is reset. Whatever the cause a sudden loss of power is clearly undesirable for electrical equipment.

Digger excavated and damaged cable causing blackout

Only a UPS System can protect against black outs. Your choice of UPS will depend upon the load you are protecting and the amount of time you need support for.

2. The Power Sag

Also known as a power dip, this is where the power momentarily drops. It’s usually caused by the start up of heavy electrical equipment. Other causes include overloads on the network, or utility switching. Note that the plant that is causing the power sag may not be in your building but sharing the same substation. The severity of the dip will impact equipment in different ways. Some equipment will have a natural ability to cope for momentary dips where others will shut down or reset.

You will need a UPS System to protect against a power sag.

3. The Voltage Surge

Some call it a spike, but in any event it’s a short term high voltage on the power line. Usually caused by lightning, which doesn’t have to be a direct hit on the power lines but nearby causing the spike to be induced onto them. The surges are generally destructive in nature as most equipment is not designed to protect against them.

A surge protector or a UPS System will protect against surges.

4. The Brown Out

This is where the voltage drops below 10% of the nominal voltage for an extended period of time. This is caused by high demand on the network. The effect is more pronounced the further you are away from the electrical substation. In fact, in rural areas this can be a problem when switching on everyday appliances such as ovens or electric showers. Brown outs affect different equipment in different ways. Computer systems tend to be able to cope well with brown outs as the switch mode power supplies have a wider input voltage. Other equipment that relies on  a stable AC source such as lighting, motors or heating will not fare so well. Equipment with linear power supplies such as in high end AV applications may fail entirely.

In order to protect against a brown out you will need some form of voltage regulation. A line interactive UPS System incorporates a boost function to raise the voltage higher by a fixed percentage to bring it into the nominal range. It does this without needing to revert to battery operation.

5. Over Voltage

Also known as a voltage swell this power problem is caused when the demand on the network is lower than normal. This causes the output voltage from the substation to rise. This is a problem when the voltage is over 10% of the nominal. The effects of over voltage can range from overheating, diminished equipment life to complete equipment failure. It’s the inverse of the brown out in that the closer you are to the substation the more pronounced the effect will be.

Similar to the brown out you will need some form of voltage regulation. A line interactive UPS System incorporates a buck function to lower the voltage by a fixed percentage to bring it back into the nominal range.

6. Electrical Noise

This is generally noise between the live and neutral conductors and is called normal mode noise. Its caused by radio frequency interference (RFI) or electro-magnetic interference (EMI). This is usually from electronic devices with high switching speeds. Since the noise carries little energy it generally does not cause damage but rather disruption in the function of other electronic systems. Some filters may remove this, but this is not always effective. The best way to eliminate noise is to recreate the output waveform and this can only be done with an online double conversion UPS System.

7. Frequency Variation

Frequency variation can’t occur on the utility as this would require all the power stations in the country to suddenly change frequency. In fact, the frequency on the national grade is very tightly maintained at 50Hz. However, when you’re not connected to the utility and instead relying on a portable (or even large scale) generator then this can be an issue. As the load increases on the generator and in particular sudden large power draws from them causes the motor to slow down and hence change the output frequency. Some equipment won’t be affected by this at all but it can cause damage to other systems, particularly those with motors or other inductive devices.

The only way to protect against frequency variation is with an online double conversion UPS System.

8. Switching Transient

More severe than electrical noise, switching transients are very fast high voltage spikes induced onto the power conductors. Caused by the switching off of inductive loads and variable speed drive systems. Such power problems may not be immediately damaging but they can cause degradation of devices subjected to them, particularly if the transient is of high enough voltage.

A surge suppressor can help if the magnitude of the transient is high enough, but these only work at levels above the nominal voltage. This means you could still have a transient of many hundreds of volts entering your equipment. Like with electrical noise a filter will help, but can only reduce a transient not eliminate it. The only way to be sure to eliminate the transient is with the online double conversion UPS System.

9. Harmonic Distortion

Harmonic distortion is where the supply voltage varies from a pure sine wave. The amount of variation is a measurement called the Total Harmonic Distortion or THD. Since we’re talking about voltage we call it THDv, not to be confused with THDi which is a measure of the distortion of input current which is a different thing entirely.

It is generally caused by non-linear loads. These are types of loads that don’t take current in a smooth sinusoidal fashion but instead take it in large chunks. Depending on supply characteristics these chunks of current cause a greater or lesser degree of distortion on the supply voltage. This causes problems for motors and transformers with hum and overheating. In three phase supplies harmonic distortion can actually cause the burning out of neutral conductors and surprise tripping of circuit breakers. Again the only way to eliminate harmonic distortion from your load is to use the  online double conversion UPS System.


That’s the main generally accepted 9 power problems that can cause issues for electrical and electronic equipment. But wait, didn’t I say there was a tenth?

10. Common Mode Noise

This power problem is often overlooked and can cause equipment malfunction. It’s defined as electrical noise between the earth conductor and the live/neutral conductors. Even an online UPS System may not eliminate common mode noise. This is because it is normal practice to have the neutral conductor connected through the UPS from input to output. So although any noise between the live conductor and ground would be taken care of, any noise between neutral and ground is passed straight through to the load.

In a modern electrical infrastructure this generally may not be a problem since the neutral and earth are tied together at the distribution board. This shorts them together and in theory eliminates any voltage or noise between them. However, particularly on long circuits with a lot of equipment on them, voltages can start to be created and common mode noise becomes an issue. Hospital laboratories are a prime example of this.

The way to solve common mode power problems is to isolate the load from the supply. This is exactly what the TX Series does. The in-built isolation transformer creates a new live and neutral, and the online double conversion technology then ensures a high quality stable output. An an added advantage the isolation transformer can provide a safety shield against electric shock which is particularly important in applications where water and electricity may mix. Again, hospital laboratories are a prime candidate. Thus the TX Series can also be defined as Laboratory UPS System. Click for further information on the isolation transformer.

The new summary is this. If you need to provide the highest degrees of power protection against power problems and viruses then the UPS Technology choice should be online double conversion, and the load should be isolated. Choose the TX Series Isolated UPS System.

TX Series Isolated UPS Systems
For the highest degrees of power protection the TX Series of Isolated UPS from 1-10KVA

Product Matrix

Black out
Power Sag
Voltage Surge
Brown out
Over Voltage
Electrical Noise
Frequency Variation
Switching Transients
Harmonic Distortion
Common Mode Noise