Five steps to select a small network UPS
Following steps provide guidance for a UPS to protect a small network of up to ten computers
from power disturbances and short power outages. If however your network is larger or in case
you need to continue working at extended power outages, please refer to a more detailed Guide
to professional UPS selection.
1. Decide the required SIZE of the UPS
UPS systems are rated according to their output Power, derived by multiplying the mains
voltage times the total current drawn by the equipment. The resulting figure is expressed by
a power unit called Volt -Ampere (VA) or KiloVolt-Ampere (one KVA equals 1000VA).
The Voltage in the VA figure, is the device voltage (mains utility,or line voltage in your country,
230 Volt in Europe, 120 Volt in USA ).The Ampere term is the total sum of the individual input
currents of all products connected to the UPS.
The Ampere (A) rating of each consumer is indicated on its nameplate. If only VA is indicated
divide it by device voltage to get the Amperage. If only Watt rating is indicated divide it by
device voltage and multiply the result by 1.5 .
After adding up the individual ampere ratings, multiply the resultant figure by the voltage to get
the required VA capacity.
Input current derived from product nameplates is generally 40% above the measured current
drawn by the UPS. This additional margin is however required for future expansion.
Connect the UPS only to critical equipment. You should back-up the computer, the
modem (if external), the communication devices,emergency back light, and the monitor if
preferred Do not generally connect the printer. Never connect a Lase printer.
2.Decide the required Backup Time.
Upon Blackout, the UPS continuous to feed the critical consumers deriving its energy from
internal or external batteries. When power is restored it it will feed the loads from mains,
recharging the batteries to replenish the charge withdrawn during the power outage.
In case of sustained outage the UPS will turn off when the charge in the battery is
withdrawn. Before turning-off, it should automatically send a shut down signal, to your
computer or network, thus initiating with the aid of special software supplied with the UPS,
file saving and graceful shut down of all computers.
In case you provide a real time service, you will probably need longer backup times. More
information is available in the Guide to professional UPS selection.
Backup time depends on the amount of Real Power drawn from the UPS, which is expressed
by a Watt (W) power figure. The ratio Watt/VA called Power Factor (PF) is dictated entirely
by the type of the Load. The power factor of a resistive load like heaters or lamps is 1, the
Power factor of a computer type loads equals generally 0.6-0.7
Thus a UPS rated 500VA/350W with 10 minutes Backup, will protect any load with VA rating
less than 500VA and Wattage rating less than 350W. It will backup 350W load for 10 minutes
before turning off. Partial load increases dramatically the back-up time. UPS manufacturers
generally provide full load and half load backup time figures.
3. Decide the TYPE of the UPS you need
UPS systems have two main functions. First, they protect the essential consumers from utility
mains phenomena, which might harm consumer's hardware or its sensitive information.
Second, they enable the UPS to back-up the critical loads upon mains outage with conditioned
power, initiating graceful turn off, in case the battery is depleted before the mains power is
restored.
It is the quality of protection that makes the difference between the types. UPS's are roughly
classified into three main categories. The Off Line UPS is the simplest and the least expensive,
then comes the Line Interactive type, which overcomes major drawbacks inherent to the off-
line unit, finally the On-Line UPS which provides the best possible power protection.
An off-line UPS, also called Stand-by or Back-UP UPS feeds the load continuously from
Mains. Upon mains outage, the load is fed from batteries through an Inverter, a device in the
UPS that converts the battery voltage to alternating waveform of the same magnitude and
frequency as the mains.
The off-line systems includes surge arresters and internal filters, thus protecting the critical load
from Power Failure, Power Sag and Power Surge, which comprise three out of nine power
related disturbance types, but constitute about 95% of measured disturbances which might
cause computer failures.
Due to the affordable price, these systems are generally used for protecting personal computers
and workstations where overcoming the nuisance involved in power outage seems to be the
main issue.
The Line Interactive UPS, called sometimes Interactive, On Line Interactive or Smart
UPS, also works directly from mains, switching to battery (via the inverter) upon mains
disappearance. Here however, additional Automatic Voltage Regulating (AVR) circuit corrects
also Undervoltage and Overvoltage power problems thus solving five out of nine possible power
disturbances. By continuously monitoring the input voltage, and keeping the output within
allowed tolerance band, it provides. Constant conditioned power to the critical load, solving
almost 99% of measured power disturbances.
Line Interactive UPS units come generally in the range of 500VA to 5000 VA, offering a
popular and cost effective solution for servers, hubs and other loads in this power range. These
systems are applied in relatively small networks, comprising 10-12 computers, in such
locations as lawyer offices, accountants, sales agencies, engineering offices etc.
An On-Line UPS, also called Double Conversion UPS, or True On-Line UPS, is the ultimate
solution for all applications from one kilowatt up to Megawatts sized consumers. Here, the load
is constantly fed from the Inverter, providing conditioned, stabilized sinusoidal voltage, isolating
it from any abnormal utility behavior. This system solves also such disturbances as Switching
transients, Line noise, Frequency Variations and Harmonic distortions, thus providing protection
to all nine AC power related disturbances.
The merits of an ON -Line system, make it the preferred choice for critical business, industrial
applications and real time service providers.
4. Optimize your selection.
The said decision steps specify the right UPS for your application, some additional items should
however be considered at the procurement stage. These, are generally found in line Interactive
and On-Line units. You might consider upgrading to line interactive type if the following
requirements are not available in the off-line unit.
goes down when the lights turn off. Don't be tempted to buy systems with
manually initiated test. Nobody remembers to keep the testing routine.
5. Buy the right UPS
Ordering the right make from the right supplier, is a key issue to finalize the right UPS selection.
At this stage you already know the Size in VA (or KVA), the Backup time and the Type . Now
you need to find the right product at the best price offered by a reliable seller.
Numerous manufacturers are probably able to meet your requirements. Most provide well
designed and reliable systems.
Following are the top brands, distributed all over the world:
APC - American Power conversion, Powerware- Eaton, Liebert- Emerson, MGE UPS
Systems, Delta Electronics, Tripp-lite, Chloride Power, Toshiba, Belkin.
To start you will need only one Right lead. Shopzilla.com is a Rating Site which enables you to
find a proper product, see a list of stores that offer the product, compare prices see store rating,
shipping information and more.
Link to Shopzilla.com, Enter in the search window the required Power and Voltage (for
instance: 1000VA 230V ). Upon selecting the UPS a new window opens with main product
information, prices and stores. More details if required may be found in the specific store.
from power disturbances and short power outages. If however your network is larger or in case
you need to continue working at extended power outages, please refer to a more detailed Guide
to professional UPS selection.
1. Decide the required SIZE of the UPS
UPS systems are rated according to their output Power, derived by multiplying the mains
voltage times the total current drawn by the equipment. The resulting figure is expressed by
a power unit called Volt -Ampere (VA) or KiloVolt-Ampere (one KVA equals 1000VA).
The Voltage in the VA figure, is the device voltage (mains utility,or line voltage in your country,
230 Volt in Europe, 120 Volt in USA ).The Ampere term is the total sum of the individual input
currents of all products connected to the UPS.
The Ampere (A) rating of each consumer is indicated on its nameplate. If only VA is indicated
divide it by device voltage to get the Amperage. If only Watt rating is indicated divide it by
device voltage and multiply the result by 1.5 .
After adding up the individual ampere ratings, multiply the resultant figure by the voltage to get
the required VA capacity.
Input current derived from product nameplates is generally 40% above the measured current
drawn by the UPS. This additional margin is however required for future expansion.
Connect the UPS only to critical equipment. You should back-up the computer, the
modem (if external), the communication devices,emergency back light, and the monitor if
preferred Do not generally connect the printer. Never connect a Lase printer.
2.Decide the required Backup Time.
Upon Blackout, the UPS continuous to feed the critical consumers deriving its energy from
internal or external batteries. When power is restored it it will feed the loads from mains,
recharging the batteries to replenish the charge withdrawn during the power outage.
In case of sustained outage the UPS will turn off when the charge in the battery is
withdrawn. Before turning-off, it should automatically send a shut down signal, to your
computer or network, thus initiating with the aid of special software supplied with the UPS,
file saving and graceful shut down of all computers.
In case you provide a real time service, you will probably need longer backup times. More
information is available in the Guide to professional UPS selection.
Backup time depends on the amount of Real Power drawn from the UPS, which is expressed
by a Watt (W) power figure. The ratio Watt/VA called Power Factor (PF) is dictated entirely
by the type of the Load. The power factor of a resistive load like heaters or lamps is 1, the
Power factor of a computer type loads equals generally 0.6-0.7
Thus a UPS rated 500VA/350W with 10 minutes Backup, will protect any load with VA rating
less than 500VA and Wattage rating less than 350W. It will backup 350W load for 10 minutes
before turning off. Partial load increases dramatically the back-up time. UPS manufacturers
generally provide full load and half load backup time figures.
3. Decide the TYPE of the UPS you need
UPS systems have two main functions. First, they protect the essential consumers from utility
mains phenomena, which might harm consumer's hardware or its sensitive information.
Second, they enable the UPS to back-up the critical loads upon mains outage with conditioned
power, initiating graceful turn off, in case the battery is depleted before the mains power is
restored.
It is the quality of protection that makes the difference between the types. UPS's are roughly
classified into three main categories. The Off Line UPS is the simplest and the least expensive,
then comes the Line Interactive type, which overcomes major drawbacks inherent to the off-
line unit, finally the On-Line UPS which provides the best possible power protection.
An off-line UPS, also called Stand-by or Back-UP UPS feeds the load continuously from
Mains. Upon mains outage, the load is fed from batteries through an Inverter, a device in the
UPS that converts the battery voltage to alternating waveform of the same magnitude and
frequency as the mains.
The off-line systems includes surge arresters and internal filters, thus protecting the critical load
from Power Failure, Power Sag and Power Surge, which comprise three out of nine power
related disturbance types, but constitute about 95% of measured disturbances which might
cause computer failures.
Due to the affordable price, these systems are generally used for protecting personal computers
and workstations where overcoming the nuisance involved in power outage seems to be the
main issue.
The Line Interactive UPS, called sometimes Interactive, On Line Interactive or Smart
UPS, also works directly from mains, switching to battery (via the inverter) upon mains
disappearance. Here however, additional Automatic Voltage Regulating (AVR) circuit corrects
also Undervoltage and Overvoltage power problems thus solving five out of nine possible power
disturbances. By continuously monitoring the input voltage, and keeping the output within
allowed tolerance band, it provides. Constant conditioned power to the critical load, solving
almost 99% of measured power disturbances.
Line Interactive UPS units come generally in the range of 500VA to 5000 VA, offering a
popular and cost effective solution for servers, hubs and other loads in this power range. These
systems are applied in relatively small networks, comprising 10-12 computers, in such
locations as lawyer offices, accountants, sales agencies, engineering offices etc.
An On-Line UPS, also called Double Conversion UPS, or True On-Line UPS, is the ultimate
solution for all applications from one kilowatt up to Megawatts sized consumers. Here, the load
is constantly fed from the Inverter, providing conditioned, stabilized sinusoidal voltage, isolating
it from any abnormal utility behavior. This system solves also such disturbances as Switching
transients, Line noise, Frequency Variations and Harmonic distortions, thus providing protection
to all nine AC power related disturbances.
The merits of an ON -Line system, make it the preferred choice for critical business, industrial
applications and real time service providers.
4. Optimize your selection.
The said decision steps specify the right UPS for your application, some additional items should
however be considered at the procurement stage. These, are generally found in line Interactive
and On-Line units. You might consider upgrading to line interactive type if the following
requirements are not available in the off-line unit.
- Make sure that the UPS comes with shut down software to enable automatic
- Verify that the UPS includes surge protectors on its input and on its
- Make sure that the UPS performs automatic test warning whenever the
goes down when the lights turn off. Don't be tempted to buy systems with
manually initiated test. Nobody remembers to keep the testing routine.
5. Buy the right UPS
Ordering the right make from the right supplier, is a key issue to finalize the right UPS selection.
At this stage you already know the Size in VA (or KVA), the Backup time and the Type . Now
you need to find the right product at the best price offered by a reliable seller.
Numerous manufacturers are probably able to meet your requirements. Most provide well
designed and reliable systems.
Following are the top brands, distributed all over the world:
APC - American Power conversion, Powerware- Eaton, Liebert- Emerson, MGE UPS
Systems, Delta Electronics, Tripp-lite, Chloride Power, Toshiba, Belkin.
To start you will need only one Right lead. Shopzilla.com is a Rating Site which enables you to
find a proper product, see a list of stores that offer the product, compare prices see store rating,
shipping information and more.
Link to Shopzilla.com, Enter in the search window the required Power and Voltage (for
instance: 1000VA 230V ). Upon selecting the UPS a new window opens with main product
information, prices and stores. More details if required may be found in the specific store.
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