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Reading: Managing power problems
Contents
Introduction
2
Types of power problems
2
Blackout ..................................................................................... 2
Brownout .................................................................................... 3
Power surge ............................................................................... 3
Protection from power problems
4
Surge arrestors........................................................................... 4
Uninterruptable power supplies .................................................. 5
Emergency generators ............................................................... 8
Procedures
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1
Introduction
All of the live systems you may be required to manage as an
Information Technology (IT) worker need electrical power to function.
More specifically, these systems will have power requirements with
varying degrees of tolerances.
Before looking at power problems in detail it is important to have a
basic understanding of terminology used to describe electrical power
needs:

Power. Expressed in watts, power is a measure of how much
energy is consumed over time. The higher the wattage, the
more electrical energy is consumed for the same amount of
time. Typically you will come across this term when working
with computer system power supplies.

Voltage. Expressed in volts, voltage is a measure of the
electric potential difference. It can be thought of as the
‘electrical pressure’ forcing electrons to flow through an
electrical circuit. The higher the voltage the greater the
electric potential difference and the greater the ‘electrical
pressure’.

Current. Expressed in amps (ampere), current is a measure
of the flow of electric charge. It can be thought of as the
amount of electrons that flow past a given point over time.
Types of power problems
Live systems will suffer errors and faults if power problems are not
managed effectively. The three main power problems you will need
to overcome are:

blackouts

brownouts

power surges.
Blackout
A blackout is a complete loss of power. The result is the immediate
turning off of all unprotected electrical devices. Blackouts may occur
for a wide range of reasons including damaged power lines, loss of
power generation, short circuits and overloaded electrical systems.
No matter what the cause of the blackout the effect is the same.
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Blackouts may last for several minutes, hours or, in extreme cases,
several days. More commonly a blackout will only be momentary ie
milliseconds to seconds. These very short dropouts in power supply
may go unnoticed by many live systems depending on how long they
last and the power needs of the device. Devices with high-tolerance
power needs suffer the most from these momentary dropouts.
Most IT hardware will not suffer any damage due to a blackout. Once
power is restored the hardware will usually function normally. The
damage usually comes in the form of lost data or corrupted software.
For a client computer, a blackout may result in the loss of a few
hours of work on several documents. In client and server computers
a blackout may also cause corruption of the operating system or
software applications. This will require some form of repair,
restoration or reinstallation, all resulting in lost productivity.
For other devices, such as switches, modems, routers etc, a blackout
will usually cause no damage or data loss. However, in some
circumstances, such as upgrading firmware or saving setting
changes, these devices can become highly susceptible to data loss if
power fails.
Brownout
A brownout is a reduction in power supply to below the minimum
requirements of the power generation system. In Australia a standard
power point supplies 240 volts at up to 10 amps. A reduction in
voltage of 8—10% usually constitutes a brownout.
Brownouts are often caused by an overloading of the local power
supply, such as on very hot days when a large number of air
conditioners are in use. Brownout may only last a short period of time
or may last several hours and may be unstable. The voltage may
cyclically drop, causing electronic equipment to intermittently
function.
Brownouts can cause strange behaviour in electronic equipment.
Computers may appear to be on but not functioning; monitors going
into standby mode. Brownouts also have the potential to cause
damage due to incorrect voltage supply and in some cases
overheating where devices draw more current to compensate for the
reduced voltage.
Power surge
A power surge or power spike is the opposite of a brownout. In a
power surge the voltage rises above the maximum voltage of the
power generation system. Power surges are usually short-lived but
the voltage increase can be extremely high.
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Power surges are typically caused by lightning strikes, sudden
decreases in power draw or faults in the power generation system.
Power surges are the most likely power problem to cause damage to
electronic hardware. The dramatic increase in voltage and current
causes a rapid increase in temperature which often results in ‘blown’
or degraded electronic components within a device. It is important to
note that power surges can often enter a device from sources other
than a device’s incoming power supply. Network and
communications cabling is another common entry point for a power
surge.
Power surges are often caused by lightning strikes
Protection from power problems
All of the abovementioned power problems can be effectively
managed to protect live systems. Through the implementation of
protection equipment and procedures, power problems may cause
some downtime but only in extreme cases should these problems
cause damage to equipment or result in data loss.
There are three main forms of protective equipment. They are:

surge arrestors

uninterruptable power supplies (UPSs)

emergency generators.
Surge arrestors
A basic surge arrestor can be purchased in a double adapter or
power board. Although cheap, a surge arrestor can protect expensive
equipment such as digital projectors, large flat-panel monitors or
televisions, printers, photocopiers, network devices such as switches,
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routers and modems. Many of these devices may not warrant
implementing a costly UPS but still require protection from power
surges which can be very damaging.
Surge arrestors try to redirect or block the excess energy from the
power surge. In many cases the attached equipment will continue to
function normally. In cases of extreme overvoltage the surge arrestor
may sacrifice itself to protect the attached equipment. If you suspect
there has been a significant power surge you may have to inspect all
surge arrestors for damage and replace those that show any sign of
malfunction or physical damage (usually due to excess heat).
Simple double adapter surge arrestor
You should select a surge arrestor based on several features:

Response time. All surge arrestors have a delay between
when the power surge occurs and when they can block or
dissipate the excess energy. The shorter the response times,
the better the protection.

Clamping voltage. Tthis is the voltage at which the surge
protection features activate. The lower the clamping voltage,
the better the protection.

Energy absorption. This is usually expressed as the maximum
number of joules the surge arrestor can absorb before failing.
The higher the number, the better the protection.
Uninterruptable power supplies
As the name suggests, a UPS will continue to supply power to a
system even if that power is interrupted by a blackout, brownout or
power surge. For business-critical systems, such as servers and core
network equipment, a UPS is a vital addition to the system design.
A UPS is connected between the mains power supply and the
protected device. If power fails (blackout) or a brownout occurs, the
UPS switches over to built-in batteries to continue to supply power
until the mains power supply returns, an alternate power supply can
be brought online (eg emergency generator) or the connected device
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can be safely shut down. If a power surge occurs, the UPS relies on
built-in surge arrestors to protect connected devices. Many UPS
devices also offer other power ‘conditioning’ capabilities to improve
the quality of power being supplied.
There are several UPS features you need to consider when selecting
an appropriate UPS:

Form factor. UPS’s are available as small stand-alone
pedestal units, rack mounted units and dedicated,
freestanding UPS systems.
Standalone UPS unit

Mode of operation. Standby, line interactive and double
conversion modes represent increasing complexity and power
quality. The mode chosen depends on the needs of the
connected devices. For more information have a look at the
following websites:
- Simple explanation of UPS modes www.elecpowertech.com.au
- Detailed explanation of UPS modes - www.mgeups.com
(requires Adobe Reader)

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Number of protected outlets. Small to medium UPS systems
allow you to connect power cords from the UPS to the
protected devices. There are differences in the number of
available power sockets and not every socket may offer
battery backup. Some sockets may only offer surge protection.
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Rear view of UPS showing six protected power sockets, two phone sockets and a
serial communications port

Management ports and software. If the battery in a UPS
becomes completely depleted it will turn off connected
devices, potentially losing data. To avoid this, most small to
medium UPS systems have a serial or USB controller port
which can connect to a computer protected by the UPS. Using
management software, the UPS is then able to communicate
with the computer, initiating a safe shutdown before the UPS
battery is depleted. The computer connected to the UPS may
also be able to act as a UPS server. When client software is
installed on other computers the UPS server can
communicate via the network to these client computers and
initiate a safe shutdown. This system relies on both the client
computers and the interconnecting network hardware to be
power protected.

VA (volt-ampere). UPS systems are commonly rated with a
VA number. This is an indication of the apparent power a UPS
is capable of supporting. The higher the VA number, the
higher the power load the UPS is capable of supporting. This
is an important figure to correctly assess. If calculated
incorrectly, when power fails, the UPS may not be able to
deliver the required power for the connected devices or may
not be able to do so for long enough to ensure a safe
shutdown of these devices. The websites of most UPS
manufacturers have guides to help you select an appropriate
UPS for the devices it will protect.
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Emergency generators
In highly mission-critical scenarios, such as hospitals, defence,
banking systems etc, any downtime of live systems can have
catastrophic consequences. In some remote locations and
developing countries, mains power supply can be very unreliable.
Utilising UPS systems alone will not ensure that computer systems
continue to function when prolonged power problems occur.
In these scenarios it may be necessary to consider the use of a
backup power generation system. This may range from a small,
portable, petrol-powered generator to large-scale, shipping-container
sized diesel generators. Despite the size the same principles apply. If
the mains power supply fails, the emergency power generation
system must be brought online before UPS batteries are depleted. A
small generator may require a manual pull-start and a transfer of
power connections. Large generator systems automatically cut in and
are integrated with a site’s power distribution system.
Except in simple, small-scale situations, the design and
implementation of emergency power generation should be left to
qualified electrical engineers and product specialists.
Small emergency petrol generator
Procedures
During times when power is affected by blackouts, brownouts and
power surges, live systems become vulnerable to hardware damage
and data loss or corruption. The abovementioned protective devices
provide some measure of protection against these consequences.
The effectiveness of a response to power problems can be
significantly improved by implementing some basic procedures.
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Reading: Managing power problems
© NSW DET 2008
The following list provides some ideas that can help minimise the
impact of power problems:

Find the source of the problem. It is important to rapidly
assess the source of the power problem as either internal or
external. For example, does the power problem affect only
your business or does it also affect neighbouring businesses?
Is it within a building or does it affect a larger region? If a
single office or building is affected the problem may be caused
by a blown fuse or a tripped safety switch from an overloaded
circuit or faulty appliance. Localised problems need to be
isolated where possible and an electrician called if necessary.
Wide area problems require contacting your electricity
provider.

Know your electricity provider. When power problems arise
most computers will go offline and PABX and VoIP phone
systems will not function. This will cut you most of your
communications. Know who your electricity service provider is
and put their emergency/faults contact number into your
mobile phone. Have a record of your account number and call
the provider so that you can quickly assess the severity and
estimated duration of the power problem.

Turn everything off. When power problems occur for an
extended time it is sensible to turn off all electronic equipment.
This is particularly the case during a brownout where devices
can attempt to function without adequate power, causing
overheating or cycling on and off.

Save regularly. In most business settings client computers do
not have a UPS attached. To avoid data loss from power
problems, staff should be trained to save work regularly. If
they are spending hours working on a document they should
constantly save their work. Some software can also be
configured to force automatic saving at regular intervals.

Regularly backup data. Power protection devices and
procedures are all part of establishing an adequate disaster
recovery plan for your business. Effective backup strategies
are an integral part of this plan. You must ensure that key data
and systems are regularly backed up so that in the event of a
power problem causing data loss or corruption the data can be
quickly restored. Don’t forget to include the configuration
settings in devices such as routers, switches, phone systems,
printers, photocopiers etc.
This reading should have provided you with an overview of the power
problems you may be faced with when managing IT systems. More
importantly, you should have a better understanding of the protective
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devices and procedures you can put in place to protect and recover
from power problem events.
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Reading: Managing power problems
© NSW DET 2008