POWER SOLUTIONS: Power struggle

Power outages, whether because of a general power failure or a failure of the

backup systems, can be tolerated to a certain level in a number of industries,

however the same can not be said of telecom services. As far as power failures

go–telecom services must be a zero tolerance zone. While even a millisecond of

outage is unacceptable in the Internet Data Center (IDC) business, services like

cellular telephony, fixed phone services and Internet services too, would prefer

uninterrupted power supply. But how do you ensure a 24 hour and seven days a

week power availability in a country like India where power outages are not

uncommon? And where even if availability is not an issue, the power input leaves

much to be desired because of surges and wide voltage fluctuations. The solution

definitely lies in deploying an adequate and efficient power protection system

that has availability and reliability as its most important attributes.

Reliability and Efficiency Issues

For telecom service providers, getting any power backup solution or

uninterruptible power supply system would not be a difficult task–they are

abundantly available. But getting a system that fits into their requirement may

be an issue of concern. Besides that, the service providers also need to ensure

that the backup solution, they deploy, meets the most stringent of availability

and reliability conditions (remember the best systems could fail at times as

happened with Exodus Communications some time back). On 7 May 2001, Exodus, one

of the largest hosting services providers, suffered an hour-long power outage at

one of its data centers in Sunnyvale, California because its backup systems

failed to neutralize a power blackout leading to the interruption of services.

This affected service to Exodus customers such as Yahoo, whose web site and

messenger service went out of service for some time.

The incident germinates the need for not only a highly reliable backup system

but also something called ‘parallel redundant operation solutions’.

"For services like IDCs, just having a backup system is not enough. While

on one hand, no shutdowns are allowed at IDCs, on the other, they need regular

maintenance to avoid possible problems. And you just cannot carry out a

maintenance without a shutdown", points out Harshesh Malhotra, divisional

manager, Tata Liebert Ltd, a leading supplier of power protection solutions to

the Indian service providers. The solution, Malhotra says, lies in deploying a

system that combines availability with maintainability allowing maintenance and

upgradation without shutdowns. ‘’Ad hoc systems like placing one UPS to back

up another won’t work in a data center like operation. What data centers can

do is to set up a parallel system that is intelligent enough to take over even

if there is a slightest failure", adds Malhotra. While Malhotra said this

in the context of IDCs, the same could be true for fixed and mobile service

providers as also ISPs. An unreliable power system could leave customers

dissatisfied, mar the image of the company and ultimately even destroy all

business.

However, reliability of a power system will not be a function of the system

alone–a lot would also depend on the kind of environment in which a power

system has been deployed. Ashwini Kumar, general manager and country head, Tyco

Electronics Systems India, lists bad input light condition leading to surges and

wide voltage fluctuations, as a major threat to the reliability of power

protection equipment. Given this, it becomes important for service providers to

give careful consideration to the immediate operating environment of the power

systems, before they grade the reliability of their system. Adds Ponam Monga, a

regional sales manager with Powerware International Ltd, "To counter

spikes, surges and fluctuations, you need a UPS with wide voltage

variations". He says that it also means that the power system should have a

technology that takes care of these anomalies in the electricity input.

Energy being a major cost input in any service provider’s operations and

also a scarce commodity, efficiency of power conversion and power protection

system could be another priority area. There is a significant potential for

energy wastage in DC standby power supply, which powers the telecom or network

equipment and which is actually the major consumer of electricity at any telecom

site. This calls for an efficient power system. But, as Kumar puts it, there are

limits to efficiency. "They are governed by things like the topology of

assembly and deployment of the power system", he adds. What Kumar says

could be an issue with many service providers in India, as not only, the AC-DC

conversion process is itself less than 100 percent efficient, but DC systems

often run at far less than full load. "The design of UPS is important as at

100 percent load, the maximum efficiency that can be achieved, is 94-95 percent.

The average efficiency levels however, do not go beyond 87-90 percent",

says Monga.

Service provider networks are expandable–as the network grows so would

power requirements. IDCs often keep adding new servers and other equipment to

meet customer demands. All this means that a power protection system must be

scalable enough to cope with increasing loads. Contingency should be in-built in

an UPS. An ideal way of meeting a contingency would always have a UPS with a VA

rating of at least 1.5 times the total VA ratings of the telecom and network

equipment.

How does the Indian Market Look?

Power solution providers got good business during 2000-2001 from ISPs and

data centers. Even though some players believe that ISPs continue to have

further business potential, business from the IDC segment has almost dried up as

most ISPs have withheld their business plans owing to a downturn in their

earnings.

"ISPs are a huge market for power solution providers. As most ISPs use

routers and servers, they all use AC power for which UPS and precision

air-conditioning is required. Besides, a number of ISPs have their own gateways

for which they need DC power", observes Malhotra of Tata Liebert. His

company sold UPS solutions worth Rs 15 crore to the IDCs in 2000-01.

Some players expect phenomenal growth from cellular services. With cell

operators adding close to two lakh subscribers a month, their optimism may not

be off the mark. As subscribers grow so would the number of base stations, and

each new base station is a new business opportunity. Moreover, power solution

providers are looking at the new cell networks (fourth license) for more

business this year. Fixed service providers like Hughes Tele.com, HFCL, Shyam

Telecom and Tata Teleservices offered good business last year. Their expansion

plans could be another new business opportunity. Besides, the

upcoming fiber optic backbones are also expected to bring good business.

That the telecom services segment is getting lucerative can be concluded from

the fact that a number of UPS manufacturers like DB Power Electronics, APC, Next

Generation Business Power Systems. TVS Electronics ,

Numeric Power Systems etc are concentrating on the ISP, telephony and data

centre services for new businesses.

Ravi Shekhar Pandey

Building Power Systems for Telecom Networks

Practically, all telecom equipment work with DC power. The voltage

levels are generally 48V or in a few cases 24V. Since a battery bank is

floated across the DC bus, to provide battery backup, the working voltage

is in reality the float voltage of the battery. For VRLA batteries, the

float voltage is typically 2.25V/cell or 54V for a 48V system and 27V for

a 24V system. The positive in a 48V system is grounded whereas in a 24V

system, the negative is grounded. This difference is due to the practice

adopted by the pioneering telecom equipment manufacturers, which is

continuing today.

When it comes to data communication equipment, one has a choice of AC

or DC powered systems. AC powered systems are used because of the

availability of uninterrupted AC power source, but in application where

reliability is the paramount consideration, as in data centers, DC powered

equipment are preferred.

• What should service providers look for in a power system?

The reliability of the power system including

batteries, in a sense, determines the reliability of the entire network.

Irrespective of the technology encompassed in the telecom equipment it

powers, if the power system is not engineered correctly or lacks a high

degree of reliability, the telecom network is doomed to failure. Hence, it

makes a great deal of sense for service providers to pay attention to the

quality of the power system they buy and also the service objective of the

organization they buy it from.

Both power plant and battery technology have made rapid

advances in the recent past. Switch Mode Power Systems (SMPS) have become

the norm, as have Valve Regulated Lead acid (VRLA) batteries. Both these

technologies make for a far more compact power plant design, modular

approach and low maintenance. Power plants are made up of rectifier

modules, controller, input ac distribution, load distribution and battery

connection modules. In addition to the important electrical parameters

like efficiency, power factor, input voltage window, EMI specifications,

etc, the best in class power plants would exhibit the following

characteristics:

• High power density leading to compact footprint.
  
  Higher the footprint, greater is the money spent on floor space for
  
  equipment rooms or shelters.

• Full front access with true hot plug-in connected
  
  rectifier modules. This reduces the risk of downtime and also
  
  increases the efficiency of the service personnel. Increasingly,
  
  pressures from customers and competition will force the service
  
  providers towards higher revenue per operating staff.

• Buy as you grow–easy expandability of modules,
  
  shelves, distribution and frames in live condition, help to keep the
  
  costs commensurate with the stage of growth of the network.

• Digitally controlled modules with digital user
  
  interface, which eliminate the need of manual adjustments by trial and
  
  error.

• Integrated input and output distribution–allows
  
  for ease of maintenance and also keeps the footprint low.

• Facility for remote monitoring and remote control.
  
  As networks increase in size, the requirement of centralized and
  
  remote monitoring surfaces, as it helps in lowering the cost of
  
  operation and maintenance. In India, operators have not yet started
  
  buying remote monitoring and control options, but it is important that
  
  the systems they buy should have this option so that when the need is
  
  felt, it is possible to upgrade the system.

• What are the other site preparation issues?

The power line condition in our country, poses

challenges of its own because of surges and the wide voltage fluctuations.

In addition to the care taken in selecting the power system, service

providers would do well to protect the power system from power line and

lightning surges. While the power plant may have internal surge

protection, this is at best of equipment level. Surge protection also

needs to be provided at the building entry level. What is most important

here is the coordination between the equipment level surge protection

device and the entry-level protection.

HSeveral service providers use servo stabilizers to

provide regulated ac input to the air-conditioning equipment as well as

the power system. While the servo stabilizer is effective at providing a

tightly controlled voltage at its output, it is extremely lethargic in

doing so. Typically, the correction factor of these servo-stabilizers is

of the order of 25 V/sec. Hence, a voltage swing of 60V at the input would

take over a second to correct the output. In the meanwhile, a magnified

voltage swing is delivered at the output. The components are subjected to

recurring stresses and result in premature failure. So, while the servo

stabilizer may be good for the air conditioning equipment, it ends up

doing more harm than good to the power system.

Earthing is another area that merits attention. Most

service providers prefer to have several earth pits for different kinds of

earthing. The result is that differences in earth resistance of the pits,

results in huge potential differences between the various earths in the

condition of a fault or surge. This could result in fault currents taking

inadvertent paths to ground, as they try to seek the path of least

resistance. An effective antidote to this is to connect all the earth pits

together at the pit level. This will not only eliminate the possibility of

multiple earth potentials, but also help in lowering the overall earth

resistance.

Appropriate selection of the generator too requires

care. Transient voltage drop and rise, and also the crest factor, are two

issues that are often missed while specifying generators. While buying

power systems, the limit for these parameters must be specified taking

into consideration its effect on the DC power system. Typically, the crest

factor should be as close to 1.414 as possible and transient voltage

dip/rise should be within ± 20 percent of the rated voltage.

Perennial Debate

Make or buy is one managerial decision that is often

revisited. Service providers always have this question before them: Should

they instal and manage the power and associated infrastructures like air

conditioning, generators shelters, earthing, fire and security systems

themselves or entrust it to the telecom equipment vendor or should they

entrust it to yet another specialist vendor?

Each service provider has his own approach that has

undergone a change as they mature with experience. As they rollout new

networks, they should limit their own resources to ensure low cost. Most

of the telecom equipment vendors are down financially and they may not

dole out vendor finance as liberally as in the past. The third route of a

specialist vendor may now look as an attractive option.

Ashwini Kumar,



General Manager and Country Head,
Tyco Electronics Systems India