Centralized vs Distributed UPS System

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.

Shielded Cables: An Effective Way to combat EMI

Electrical noise, either radiated or conducted as electromagnetic interference (EMI), can seriously disrupt the proper operation of other equipment. Insulation protects a cable mechanically from scraps and abrasion and environmentally from moisture and spills. But insulation is transparent to electromagnetic energy and offers no protection. Shielding is needed to combat the effects of EMI. Cables can be a main source of transfer for EMI, both as a source and receiver. As a source, the cable can either conduct noise to other equipment or act as an antenna radiating noise. As a receiver, the cable can pick up EMI radiated from other sources. A shield works on both.
The primary way to combat EMI in cables is through the use of shielding. The shield surrounds the inner signal- or power-carrying conductors. The shield can act on EMI in two ways. First, it can reflect the energy. Second, it can pick up the noise and conduct it to ground. In either case, the EMI does not reach the conductors. In either case, some energy still passes through the shield, but it is so highly attenuated that it doesn’t cause interference. Cables come with various degrees of shielding and offer varying degrees of shielding effectiveness. The amount of shielding required depends on several factors, including the electrical environment in which the cable is used, the cost of the cable—why pay for more shielding than you need?—and issues like cable diameter, weight, and flexibility.
There are two types of shielding typically used for cables: foil and braid.
Foil shielding used a thin layer of aluminium, typically attached to a carrier such as polyester to add strength and ruggedness. It provides 100% coverage of the conductors it surrounds, which is good. It is thin, which makes it harder to work with, especially when applying a connector. Usually, rather than attempting to ground the entire shield, the drain wire is used to terminate and ground the
shield. A braid is a woven mesh of bare or tinned copper wires. The braid provides a low-resistance path to ground and is much easier to termination by crimping or soldering when attaching a connector. But braided shields do not provide 100% coverage. They allow small gaps in coverage. Depending on the tightness of the weave, braids typically provide between 70% and 95% coverage. When the cable is stationary, 70% is usually sufficient. In fact, you won’t see an increase in shielding effectiveness with higher percentages of coverage. Because copper has higher conductivity than aluminium and the braid has more bulk for conducting noise, the braid is more effective as a shield. But it adds size and cost to the cable. For very noisy environments, multiple shielding layers are often used. Most common is using both a foil and a braid. In multi conductor cables, individual pairs are sometimes shielded with foil to provide crosstalk protection between the pairs, while the overall cable is shielded with foil, braid, or both. Cables also use two layers of foil or braid.
In practice, the purpose of the shield is to conduct to ground any of the noise it has picked up. The importance of this cannot be overstated—and failure to understand the implications can mean ineffective shielding. The cable shielding and its termination must provide a low-impedance path to ground. A shielded cable that is not grounded does not work effectively. Any disruptions in the path can raise the impedance and lower the shielding effectiveness.

Fiber Optic Facts

The fibre optic cable market is growing rapidly, due to the increasing demand for fibre internet. Fibre optic cables transmit data more quickly, more reliably and over greater distances than copper-based cables. Fibre optic cables are made up of several hundred fine fibres, comprising a synthetic silica core infused with boron and germanium and a silica cladding with a lower refractive index. The purpose of the cladding layer is to maintain the optical signal within the core and to add some mechanical strength. Data is transmitted through fibres by shining light through the cable. The light travels as a guided mode, which can be considered for simplicity as bouncing off the walls of the core, known as total internal reflection. The data is transmitted in binary, with a flash of light representing a 1 and an equal period of darkness representing a 0. This allows the data to be transmitted at a rate of more than 120,000 miles per
second!

The installation phase of a fibre optic cable is the most important step towards reliable data transmission at high speed, care must be taken to ensure that the cable while installing is not bent stretched or deformed. If mishandling is done, the best case is that the fibre core will break and be faulty, however, the worst case is that the fibre optic core will be damaged and cause signal distortion, which results in intermittent faults.

The glass core in a fibre optic cable is very fragile, it is found to be slightly thicker than a human hair but made of glass. Single mode fibre uses a special type of glass that is extruded into a solid medium to protect it. Multimode fibre is made from glass but being thicker (at 50 µm compared to 9 µm), is more robust. Because of this, Single mode fibre is more sensitive to breakage than Multimode. The cladding and buffer around the cable core helps to prevent damage; however, if the core is stretched or bent beyond its limit, the core will break.

When the fibre optic is physically compromised, there are two outcomes. One case is that the two glass core pieces are not physically aligned and no laser light will propagate. This case is seen as the best scenario as the fault can be located and fixed. The second case is that the glass core will be partially aligned after the breakage and pass a partial signal. The network may or may not work due to the drop in laser power. Another strong possibility is that the glass core could be damaged instead of being broken. For single mode fibre, the glass core might only crack and cause imperfection in the medium, which would reduce signal propagation and cause reflection. Multimode fibre is more likely to be damaged by flexing and cause loss of power.

Singlemode vs Multimode

Over the past several years’ demand for higher bandwidth and faster speed connections has increased the growth of fibre optic cable market, especially the single mode fibre (SMF) and multimode fibre (MMF). Although these two types of fibre optic cables are used in numerous applications, they are very different from one another in terms of construction, fibre distance, cost and fibre colour. Single mode fibre means the fibre permits one form of light mode to be propagated at a time, however multimode fibre means the fibre can propagate multiple modes at a time. The difference between the two mainly lies in the fibre core diameter, wavelength, light source and bandwidth.

Core Diameter
The core diameter of single mode fibre is way much smaller than the multimode fibre. The typical core diameter for single mode fibre is 9µm and the typical core diameter for multimode fibre is 50µm and 62.5µm. This difference of core diameter enables MMF to have higher “light gathering” ability and simplify connections.


Wavelength & Light Source
The single mode fibre uses a laser or laser diode source to produce the light injected into the cable, the most commonly used single mode fibre wavelength is 1310nm & 1550nm. While due to the large core size of the multimode fibre, light sources like LEDs (light emitting diodes) and VCSELs (vertical cavity surface-emitting lasers) that work at the 850nm and 1310nm wavelength are used in MMF.

Bandwidth
The single mode fibre bandwidth is theoretically unlimited due to the fact that it allows one light of mode to pass through at a time. However, the multimode fibre bandwidth is limited due to its light mode and the maximum bandwidth.

Differences in Distance


According to the chart illustrated above, it can be observed that SMF distance is visibly longer than that of MMF cables at the data rate from 1G to 10G, however, OM3/OM4/OM5 fibre optic supports higher data rate due to the larger core size and also because it supports multiple light modes. The limitation of distance is due to model dispersion, which is a common phenomenon in multimode step-index fibre.
In the end, it can be concluded that both single-mode and multimode have their own characteristics. Single-mode fibre cabling system is suitable for long-reach data transmission applications and widely deployed in carrier networks, MANs and PONs. On the other side, the multimode fibre cabling system has a shorter reach and is widely deployed in the enterprise, data centres, and LANs. No matter which one you choose, choosing the one that best suits your network demands is an important task for every network designer.

In-building DAS

Distributed Antenna Systems (DAS) are networks that enhance communication in areas that do not have good coverage. Real estate companies, building owners, and others are beginning to see wireless as a “fourth utility” after water, power, heating and cooling. Today, reception of mobile service indoors is a prerequisite in multitenant commercial and residential properties. Office environments in which individuals cannot check their smartphones or place a call during a break in a meeting or conference leave impressions—negative ones.

The challenge in both commercial and residential multi-tenant properties is that energy-efficient building materials interfere with RF signals and cell coverage is observed to be largely poor towards the top floors. For owners of high-end properties, poor mobile service coverage diminishes the appeal of a residential unit or prospective office location.

Having an in-building wireless strategy, such as a Distributed Antenna Systems (DAS), is a way that many building owners are combatting this problem and improving the signals in their properties, thus increasing their perceived value by tenants, employees, and customers alike.

Treating in-building wireless coverage like a fourth utility can be a way for building and venue owners to compete in the new wireless world. If you do not have a comprehensive wireless strategy, you are likely missing future revenue opportunities and can end up spending excess money on multiple systems if not designed to work and scale on one infrastructure.

Benefits of in-building DAS

  • Improved coverage in an area that otherwise has poor signal or coverage.
  • Have fewer coverage gaps.
  • Greater coverage while using less overall power.
  • Greater safety to the public, including people who work and live in a space, as well as First Responders in an emergency.
  • Increases productivity by making in-building communication easier and more reliable.
  • Enables consistent communication across crowded venues, thus enhancing public safety, security, and helping events run smoother.

Signs your venue or building will benefit from a Distributed Antenna System

  • Frequently call drops – If cell phone calls and radio signals frequently drop inside of a building, a DAS may offer the appropriate solution. It is common for certain floors of a building to get better reception than others. If you must find a certain window on a certain floor to get okay service, it’s time to consider adding an in-building DAS.
  • People go outside the building to get better reception – If everyone in the building resorts to huddling around the lobby or outside the building to make a call, efficiency could be improved with a DAS.
  • Messages are difficult to send – Multimedia messages take more service to send and may be close to impossible to send or receive when inside of a building that needs a Distributed Antenna System.
  • You do not meet local standards for First Responder communication – It’s imperative that First Responders can communicate in an emergency from all points of your building. A lack of radio signal can impair this from happening and could lead to dire consequences.