|
|
|
07 August 2008 |
 |
| Index of UPS ‑ Single Phase |
| MGE |
| Powerware |
| 110V AC UPS |
| Chloride |
| Guide to UPS |
| Index of UPS ‑ Three Phase |
| Riello |
| Powerware |
| Chloride |
| Guide to UPS |
| Marine |
| Military |
| Process/Water |
| Product Index |
 UPS ‑ Single Phase |
| UPS ‑ Three Phase |
| Generators |
| Battery Packs |
| DC Power Solutions |
| Bypass Switches |
| Custom Power Solutions |
| Case Study Index |
| Military |
| Industrial |
| Commercial |
| Public Sector |
| Overview |
| UPS Maintenance |
| Generator Maintenance |
| Battery Replacement |
| Electrical Installation |
| Relocation & Expansion |
| Disposal |
| Other Services |
| Overview |
| Batteries |
| UPS Maintenance |
| Warranty Upgrades |
| Software |
| Warranty Details |
| Warranty Upgrades |
| Warranty Return Form |
| Warranty Registration Form |
| Warranty Terms & Conditions |
| UPS Repair |
| Generator Repair |
| Customer Repair Order Form |
 Home |
| Sales |
 Products |
| Services |
| Case Studies |
| Service |
| Services |
| Products |
| Warranty |
| Repair Centre |
| NHS |
| Custom Solutions |
| Marine |
| Military |
| Process/Water |
| About Us |
| Our Customers |
| Feedback |
| Contact Us |
|
|
|
|
 |
|
|
| |
The following links on this page will explain in greater detail the differences between the varying types of UPS,
illustrate the applications of UPS and show a useful guide to calculating VA ratings.
Functionality of Series 3 or Standby / Off-Line UPS
Functionality of Series 5 or Line Interactive UPS
Functionality of Series 9 or True On-Line UPS
Applications of UPS types
A Guide to Calculating VA Ratings
There are three main types of UPS technology currently available in the market place today,
which are as follows:-
| |
Standby
Line Interactive
True On Line
|
|
- generally known as Off line UPS
- sometimes referred to as Buck & Boost
- known as Double Conversion
|
Between them they cover the nine possible power problems commonly encountered with any
main AC supply, namely:
| Problem |
Standby |
Line Interactive |
True
on-line |
Typical applications |
| 1. Power failure |
YES |
YES |
YES |
Small or home office |
| 2. Power sag |
YES |
YES |
YES |
Standalone PC's |
| 3. Power surge |
YES |
YES |
YES |
Rolling door shutters |
| 4. Under voltage |
NO |
YES |
YES |
Office environment, small servers, PC's |
| 5. Over voltage |
NO |
YES |
YES |
Rack mount equipment and network devices |
| 6. Switching transient |
NO |
NO |
YES |
Process automation and control equipment |
| 7. Line noise |
NO |
NO |
YES |
Hospital and laboratory equipment |
| 8. Frequency variation |
NO |
NO |
YES |
Telecomms and networks, offshore projects |
| 9. Harmonic distortion |
NO |
NO |
YES |
Industrial controls, manufacturing machinery |
It is clear from the above that if you are to protect mission critical electrical equipment then
the only Uninterruptible Power Supply solution to select is the “9 Series” or TRUE ON–LINE DOUBLE
CONVERSION UPS System.
It is due to the above that Harland Simon UPS manufacture and actively promote single and
3 phase “Series 9” True On-Line UPS systems.
Please note that alternative standby and Line interactive UPS are available – please contact
our sales office for details.
| |
Standby Units: “Series 3” Protection from mains power problems 1 to 3
Off-Line means the Inverter is off and not always in circuit
There is no “built in” static bypass switch
Basically a Series 3 UPS comprises of a small filtering circuit for spikes and surges
and an “off-line” inverter. The input and output voltages remain basically the same,
within tolerances typically 190V and 255V AC. If for any reason the input voltage falls
below or rises above this tolerance then the microprocessor switches to the batteries
to supply the output for the load. This “switching” time is referred to as transfer
time and can be anything from 4-20m seconds.
Advantages
Low Cost
Disadvantages
Only protects against power problems 1-3
Poor output voltage and frequency regulation
Doubt as to whether the unit will function correctly, e.g. faulty battery
Poor output voltage waveform on battery
Short duration back-up time
|
 |
Figure 1.
Simplified line drawing of an Off-line Unit |
|
| |
Line Interactive Units: “Series 5” Protection from mains power problems 1 to 5
Line Interactive means the Inverter interacts with the line (main AC supply) smoothing the waveform
There is no “built in” static bypass switch
Basically a Series 5 UPS comprises of the same general components as the smaller off line
units but with the added ability to correct the voltage rise or fall without detriment to
the critical load. If for any reason the input voltage falls below or rises above this
tolerance then the waveform is either boosted or trimmed accordingly. However most
manufacturers tend to omit the transfer time for these units and very often these are
masquerading as “near on line” units. The static switch is also absent from this type
of UPS. Some of the more popular makes also incorporate dual relays and rely on the battery
relay to alert the user that the mains has failed. Again should any of the internal workings
of this type of UPS fail at any time during normal mains operation then the critical load
will fail.
Advantages
Low Cost
Ability to “clean” the mains to a slightly better level
Disadvantages
Only protects against power problems 1-5
Limited ratings available
Doubt as to whether the unit will function correctly, e.g. faulty battery
Poor output voltage waveform on battery
Short duration back-up time
|
 |
Figure 2.
Simplified line drawing of a Line Interactive Unit |
|
| |
On-Line Units: “Series 9” UPS Protection from mains power problems 1 - 9
On-Line means the Inverter is permanently on line all the time protecting the load.
True on line units operate in a completely different way to both standby and Line Interactive. Firstly
they do not allow the critical load to be exposed to the incoming main supply. The incoming AC supply is
converted to DC utilising a rectifier/charger section and then the AC is recreated by the inverter section
to completely regenerate clean mains power.
These units tend to have a wider input tolerance than the off line units and also the output from this
type of unit is regulated to a better degree.
If for any reason the input voltage falls below or rises above this tolerance then the rectifier shuts
down and the battery supplies power to the inverter. There is no transfer time as the unit is already
drawing power from the Inverter; hence the term ON LINE, as the inverter is in continual operation.
Therefore ON LINE does not mean directed connected on line to the computer.
Another important factor is the presence of a static switch. Under normal mains operation if a fault or
overload occurs the static switch will protect the Inverter and bypass the internal workings, during
which there is no break in supply to the critical load. The unit will then alarm to signify that there is
a fault or shut down accordingly.
 |
Figure 3.
Simplified line drawing of an On-Line Unit |
|
Standby Units
Most standby units tend to be used for smaller non critical desktop applications such as desk top computers and modems.
Physical size, VA rating and price make it more attractive for this type of low value application (usually rated to a
maximum of 1kVA). There are very few long runtime applications for this type of unit as there is usually no facility to
increase the battery string. Typical runtimes are 4-7 minutes. Interface ports and communications may be limited on some
manufacturers units.
Line Interactive Units
This unit is one of the most widely used, as it covers the range of sizes for smaller computers up to some of the medium
range. As some manufacturers sometimes masquerade these as “on line” units they can sometimes be found operating some
very critical equipment. The end user is very often unaware until something goes wrong with the UPS. With ratings up to
2000VA runtimes are usually 5-10 minutes however there are some models which the end user can add additional battery
strings to increase the runtime to several hours. Interface port and communication options more advanced than the off
line units.
On Line Units
On line units cover the largest range of VA ratings, usually from 500VA to 20kVA single phase and up to 400kVA three phase,
increasing to 2MVA for parallel systems.
They can be used in critical applications from desk top computers, network
servers, mainframes, air conditioning, fire alarms, telecom, CCTV to complete office blocks. In fact any voltage sensitive
equipment that requires mains power to operate. The battery runtime can also be extended by adding additional strings of
batteries from minutes to several hours. Larger single and three-phase equipment with additional battery strings would
require specialist installation. Interface port and communications vary from manufacturer to manufacturer, but they are
all very functional.
Summary
For the vast majority of Harland Simon UPS customers, the ideal solution is to utilise the On–Line units. Quite simply
the small additional cost of installing an on–line UPS is vastly outweighed by the technical advantages gained and the
potential loss of business should the lower value Off-Line / Line Interactive UPS fail.
This simple calculation is widely used in the UPS industry, and removes the need for expensive monitoring systems.
Obtain the total number of WATTS or AMPS for the load to be supported. For a figure given as WATTS,
divide by the power factor (if known) - The average used is generally 0.7. for single phase and 0.8
for 3 phase.
Example
|
Description
|
On-Line UPS Rating
|
800W divided by 0.7 power factor = 1143VA
|
If the figures available are in AMPS, then this can be multiplied by the nominal voltage.
|
1500VA |
2A multiplied by 230V = 460VA
|
For a three-phase application the principal is the same but the single-phase answer is finally
multiplied by three.
|
700VA |
16A multiplied by 230V = 3680VA. x 3 = 11040VA
|
Once the rating has been calculated choose an UPS with the next available VA rating higher than the
calculated one.
|
12kVA or possibly 15kVA |
|
|
|
|