When choosing a UPS solution its power rating must be taken into account and it should match the requirement or else it could fail when it is needed the most. But unfortunately choosing the correct power rating is not as easy or straightforward as it may seem.
Power factor is a quantity which has important implications when sizing a UPS system and power distribution equipment. Power is a measure of the delivery rate of energy and in DC (direct current) electrical circuits are expressed as the mathematical product of Volts and Amps (Power = Volts x Amps). However, in AC (alternating current) power system, a complication is introduced; namely that some AC current (Amps) may flow into and back out of the load without delivering energy. This current, called reactive or harmonic current, gives rise to an “apparent” power (Volt x Amps) which is larger than the actual power consumed. This difference between the apparent power and the actual power gives rise to the power factor. The power factor is equal to the ratio of the actual power to the apparent power. The apparent power is expressed as the Volt-Amp or VA rating. Therefore, the actual power in any AC system is the VA rating multiplied by the power factor.
To size a UPS and ensure that the UPS output capacity is sufficient, both the VA rating and the Watt rating of the load are important. The watt rating of the UPS relates to the amount of power it can deliver, and the VA rating of the UPS relates to the amount of current it can deliver. Neither the Watt nor the VA rating of the UPS can be exceeded. The best approach is to size a UPS the Watt rating of the load. This is particularly true for larger IT installations where the power factors of the loads are nearly 1.
If there is confusion regarding power ratings or power factor, and it is desirable to ensure the load can be powered by the UPS, then choosing a UPS with a Watt rating greater than or equal to the VA rating of the load will always ensure a safety margin. Power factor has an important implication in the specification of UPS run time on battery. Battery run time is dictated by the watt load on the UPS. However, when many UPS manufacturers specify run time at full load they are referring to full VA load, not the full watt load.
Input Power Factor:
Input Power factor is the percentage of electricity that is being used to do useful work. It is expressed as a ratio. For example, a power factor of 0.72 would mean only 72% of your power was being used to do useful work. Perfect power factor is 1.0, (unity), meaning 100% of the power is being used for useful work.
Output Power Factor:
Output power factor rating is the percentage of electricity that is available to do useful work. For example, a power factor of 0.80 would mean only 80% of your power is available as real power to do useful work. Perfect output power factor is 1.0, (unity), meaning 100% of the power is available for useful work.

Conclusion:
Power factor is a major consideration when selecting a UPS, but unfortunately, it remains a misunderstood subject, and ignoring or misapplying the power factor concepts could result in a number of problems. It is really important to understand that if the ups cannot handle the real power and the reactive power consumed by the load, a situation can develop due to overload and that could quickly lead to UPS damage.

In the in-building DAS connectivity world, progress is often viewed through the lens of enabling pervasive data connectivity for all employees working in a particular building at a given time. However, the impact of smart buildings and Internet of Things (IoT) in general, will have a potentially greater impact on in-building networking requirements going forward.

Although many building owners are starting to view the quality of their in-building cellular network as a fundamental facility, there is still a sizable sentiment within the commercial real estate industry that connectivity is a tenant and/or cellular service provider issue. As the Internet of Things (IoT) continues to proliferate, properties that do not have an adequate in-building network infrastructure to support applications and services in the 5G era will find it difficult to compete for tenants. Naturally, no one in the real estate ecosystem wants this to happen.  As the next phase of in-building wireless connectivity unfolds, below are few recommendations to help support new and/or ongoing deployments.

Large venues: Despite the fact that most airports, large malls, and entertainment venues have at least partial DAS installations and some level of public Wi-Fi connectivity, owners of these properties must take the next step. This includes becoming more aggressive deploying complete DAS networks that will offer a migration path to 5G. It also means working with an ecosystem of partners that will help deliver a premium experience to attendees.

Neutral Host investment models are needed: Although large, marquee venues can often attract a major wireless carrier to lead investments into DAS and other in-building connectivity solutions; there is a quick drop off in carrier willingness to invest in venues that do not fall into the “largest venue” category. In these cases – which represent approximately 95% of commercial real estate throughout the world – stakeholders need to consider Neutral Host Models that will help to spread the cost of comprehensive in-building networks among a number of investors that stand to benefit.

Technology providers must step-up to make investments count: If a material investment hurdle into next-generation in-building wireless networks is a fear on the part of building owners and/or tenants to invest in technology that can be rendered obsolete before the investments can be adequately depreciated, then technology providers need to work with investment stakeholders to ensure that investments made today remain relevant as the market moves towards 5G. In many cases, this means providing technology with logical and flexible evolution paths from the current state of the art to future developments (i.e. 4G/LTE to 5G). However, beyond this, it can mean working with building owners to help schedule investments in a way that creates attractive ROI models for both the short and long-term.

PIM is described as a form of signal interference that can be caused by either metal components near Passives or two or more carriers sharing the same downlink path in a wireless network, which is becoming more common as wireless networks have become more complex with multiple technology generations such as 2G 3G, LTE and now we will be moving towards 5G. The signals combine to generate unwanted interference, which impacts the signal.
A lot of importance has been given to mitigate PIM nowadays, the reason being the increase in data usage especially indoors, has pushed operators to increase the spectrum for LTE Deployments, which calls for additional frequency bands combined into Indoor DAS by each operator. To stay competitive Telecom operators care a lot about user experience, and PIM is a big hurdle in providing the great user experience. The unwanted signals produced can degrade call quality and reduce the capacity of a wireless system.
High PIM means bad cellular connection and limited bandwidth to the end user, which in turn means lost customers for the operator. Low PIM means strong signals with more bandwidth for more users, which means happy customers and higher revenues for the operator. From a hardware perspective, it means that each and every connection must be designed to minimize PIM and tested to ensure it is installed properly.
Reports show that a slight increase in PIM value could have drastic impacts on downloading speeds. At this point, we should also consider what PIM value is usually acceptable. Well, the answer to that is it depends on which passive products are we talking about. For instance, the products that are close to the base station or the first passive component right after base station (POI, Splitter, and Coupler); -160dBC PIM rating is recommended because of the high power generation of the base station. On the other hand, the passive components that are far away from the base station -150dBC PIM rating would do the job too. By the time the signal reaches the antenna, the RF power is much lower, typically on the order of 100mW (20 dBm). Given the low power level and the high loss between the antenna and the signal source, it’s hard to believe that PIM generated at or beyond the antenna could possibly be high enough to impact system performance. Experience shows that due to the highly non-linear objects often found near antennas, harmful PIM is still possible. This is especially true at low frequencies (700 MHz, 800 MHz and 900 MHz) where the probability of PIM sources occurring inside the antenna’s near field increases. For this reason, PIM is still a concern at or beyond antennas in a DAS.
Regardless of the DAS architecture (Active or Passive DAS), there will be sections where PIM can occur. In a purely Passive DAS, everything beyond the operator’s radio is a place where harmful PIM can occur. With the many splitters, combiners, coaxial cables, and antennas required to distribute the RF signals, the possibility of PIM is in a large number of places. In the image shown below, there are over 150 locations where PIM could occur:
• 64 RF connections
• 31 cable assemblies
• 15 antennas
• 14 power dividers
• 1 hybrid combiner
• 1 RF termination

Linearity in Distributed Antenna System can be improved by using components that are factory tested for PIM, making sure all RF connectors are tight and clean, apply correct assembly torque, and locating antennas away from PIM sources such as pipes, lighting fixtures, and fans.

In today’s competitive world Uninterrupted Power Supply is crucial for businesses; to keep their daily operations running smooth, no matter how big or small the organization is the continuous distribution of power throughout the infrastructure is extremely important to save the costs linked with downtime. UPS power backup is traditionally deployed in two ways; one is a centralised system and the other being distributed system. While they serve the same purpose which is to keep your business (equipment) running through blackouts, electricity fluctuations & other power issues, but they do the job in different ways.

Centralized vs Distributed UPS System:
Both of the ways have their own advantages and disadvantages keeping in mind the ease of installation, reliability, cost & scalability.

1. Ease of installation:
In terms of installation, you might think that a centralized UPS would be easy to install than various distributed UPS systems. Well, the answer is NO, the reason being if the Centralized UPS is a 3-Phase system, it requires extended expertise in installing it properly and regular maintenance. This might not be the case in adopting the distributed approach. You may use a single phase UPS which is far easier to install and requires little or no maintenance at all.

2. Reliability:
The level of critical load the system is supporting is also an important consideration. Popular belief is that a 3 phase UPS is more reliable than a single phase UPS reason being a longer mean time between failure (MTBF) because it has a built-in redundancy feature. Yet it’s not that simple, at times when you have a problem (Technical fault) with a centralized UPS, it will put all of the loads it is protecting at risk. On the other hand, the distributed approach will only affect the chunk of load it is protecting and the UPS can be easily replaced without agitating the entire operation.

3. Cost:
While the initial cost of purchasing a centralized UPS may be less over distributed UPS system, but as mentioned before the complex installation of a centralised UPS will cost much more than a distributed system in general.

4. Scalability:
Keeping in mind changing business needs, at some point in future your power requirements may increase. Adding power backup in a distributed UPS system is easier by simply adding a UPS, whereas in centralized UPS system scalability can be limited and more costly as all of the components are confined to one location.

Depending upon the preferences that are important to your organizational needs; be it cost, efficiency, reliability or ease of use and scalability, the decision rests in the hand of technical managers to determine which strategy is best to opt for.