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Emergency Electricity
Switches, routers and expensive servers need
constant and protective feeding during electricity
fluctuation or sudden disconnection and connection.
In addition to the mentioned problem, by using UPS,
we can continue working with equipment for a time
during disconnection. These systems have to types;
on line type for highly sensitive set as medical
equipment of operating-room in hospitals, off line
type for less sensitive set as computer. The online
one always converts the direct current of batteries
into 220 volt alternating current. But in the
offline type, it takes two milliseconds during power
cut so that the converter converts battery voltage
into 220 volt alternating one. Different powers
generate 400 volt ampere to several kilo volt
amperes. UPS choice needs the calculation of
consumption power and required electrification time.
1) Some points must be taken into
consideration in UPS choosing:
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●The specification must be to the technical
specifications' extent and answerable to the
UPS testing stages.
●The Supplier Company must have technical
educated agents in the cities which the UPS
is installed.
●The Supplier Company must have MANUAL
SERVICE so that if the UPS needs repairing,
it is done as the special technical
specifications.
●At least, one year warranty.
●The batteries must be able to supply the
required time of the user for BACK UP.
●The server's UPSs must have the power of
software service presentation on the used
network's software in user set. |
2) Physical specification and montage approach
must be as following:
●UPS must take a small volume so that the
maximum 5KVA dimension with batteries, takes less
than 70×70×70 cm.
●The boards must be designed and constructed as
module and separately so that in service and support
stages, the different parts of UPSs have not any
effect on each other and also the reparation and
support's expense is decreased. By this approach,
the reparation and support operation is done more
quickly.
●The power units (transistors) must be insulated
physically against wave's control and generation
units. This case prevents from the entrance of
sucked up dust of fan into the sensitive parts.
●The radiator of the transistors must have current
channel, fan and heat sing, and the fan must be
located in front of the current channel. This set
must be insulated against other section of UPS. This
mode is the best one for cooling the transistors and
preventing the entrance of the fan's dust into the
other sections.
●Transistors of the internal UPSs must be of new and
powerful MOSFET types. The usage of BIPOLARs in UPS
that were consumed in the last decade and have low
output is not recommended.
●It is recommended to use vocal and light alarms on
the different boards of UPS, to make easy the
service, reparation and support process. Their
instruction is explained in the directory.
●The UPS's box has the required firmness, the rivets
or bolts are not used for connection.
●The internal units of the box are galvanized
against humidity.
●It is better that the frame of the floor and back
panel is galvanized to prevent from oxidation.
●It is better to use a metallic frame in the floor
for strengthening, in addition to the usage of
suitable iron for heavy transistor installation, to
prevent damage during transportation.
3) The tests which UPS must answer:
●Transfer time in UPSs, sinus or sinoid, in
conformity to the 446-IEEE standard must be less
than one quarter of the city current cycle. It is
tested by STORGE-SCOPE.
●THD of the linear load must be less than 3% in
sinus UPS. (The instrument of the parameter must be
presented by the manufacturer)
●THD of the nonlinear load in sinus UPS is less than
5%.
●The power of the sine wave UPS is unchangeable
throughout the range.
●During the work of UPS, it must be protected when
the plug is connected to the socket (positive
feedback).
●The efficiency of the sinus UPS is more than 85%.
●The output regulation must be within the limit of
less than 2/5%.
●The resonance UPS, in addition to the problem of
nonconformity with sine wave, has high temperature,
noise and etc problem. So, it is better not to use
this technique in UPS construction.
●It is better that the UPS has a stabilizer so that
keep the output rationally stable during the
fluctuations of the current, without usage of
battery.
●Required protection:
1. Short circuit output protection.
2. Inverted batteries' connection protection.
3. Overload and related alarm protection.
4. Over charge and discharge protection.
5. Spike protection.
6. Over voltage and under voltage protection.
7. Output over voltage protection.
8. Battery over voltage connection to the input and
alarm activate protection. The system would not
damage if more batteries are connected to the UPS
input.
9. Input's fuse protection with standard and
automatic fuses.
10. The temperature of 0 to 40 degrees centigrade at
work.
11. 1%+ 50HZ output frequency.
●Some points about calculation of full power UPS
battery
By considering the several and more than an hour
current disconnection, it is required that UPS
batteries can present service for more than an hour.
A 5000VA UPS, other than more than an hour service,
must have the frequency and heating capability.
The AH for a 5000VA UPS with DC voltage of 48 input
is calculated as followed:
105 AH= 5000watt
So, the maximum which is required for the usage of
48 model battery is 105 AH.
Considerable points about batteries:
Batteries are divided to two types; Peculiar to UPS
and Start model
Disadvantages of Start batteries:
1. They must always be in move and they would face
problem in the stable situation.
2. They have been constructed for the short term
starts; they are damaged if used for long term by
UPS.
3. They must be charged by dynamo, after start
current supply.
Advantages of the Peculiar to UPS batteries:
They are designed for high current and long term
usage, peculiar to UPS. Their installation in one
location would not make any problem for their active
composition. By considering the used quality and
technology in their construction, repeated charge
and discharge would make no problem.
Suitable condition for Ups and related batteries
installation:
Since UPS has the POWER equipment and connects the
emergency electricity of one or some sensitive
computer, it is required to keep in desirable
condition.
Installation location:
●By considering the temperature, it must be in the
range of 10_35. (It has more importance for the
battery installation location rather than UPS.)
●The temperature must be less than 95%.
●The installation location must not have any
vibration.
●It is better to use fan for suction of the
environment heat that is produced by UPS
performance.
●As far as possible, the UPS must be in a place
where no rain, water or etc (in the kitchen) is
spilled on it.
●By considering the sensitiveness of the electronic
parts, avoid putting the UPS before dust.
●By considering the UPS alarm, Ups must be located
in a place where the vocal and light alarms are seen
easily. Avoid seriously from putting in the
reservoir.
●By considering the sensitive protection of the UPS,
it is required that a suitable card is connected to
it, for current supply.
●By considering the possibility of usage of the UPS
software capabilities, it is better that the maximum
distance between UPS and related SERVER be as the
232RS standard. It means less than 5 meters.
With help of Double Conversion design, the output
current will be full sine current that is regulated
completely in respect of voltage and frequency and
its noise has been decreased to the desirable level.
Usage of 32 byte Motorla central processor:
By usage of 32 byte Motorla microprocessors and
quick and firm approaches of processing, these UPSs
can entirely control the internal and external
activities of the system quickly and precisely, and
also they can make assurance of the output's
safeness. |
