What is a UPS?

UPS is a power supply system with energy storage which ensures a permanent supply of the load in case of a supply voltage breakdown.

Why do you need a UPS?

An Uninterruptible Power Supply (UPS) is used to protect critical loads from mains supply problems, including spikes, voltage dips, fluctuations and complete power failures using a dedicated battery. A UPS system can also be used to ‘bridge the gap’ whilst a standby generator is started and synchronised.

What should be considered when buying a UPS system?

Existing Installations: Consider a central back-up system to eliminate expensive re-cabling. Wise to involve a company specialising in power conditioning.
New Installations: Access the level of power protection required. Some installations may demand that every item is supported by UPS, others may only require UPS for a central server and one or two workstations.
Type of Client/Application: Emergency services, financial institutions, Industrial etc. This can have an impact on the system specification.
Site Location: Inner city areas may be more susceptible to power fluctuations. Rural areas may be affected by weather conditions on power lines. More remote areas may be located at the very end of the power line.

What is Sine wave ?

It is the ideal waveform for the transfer of AC power. There are two types of waveforms available. A "modified sine wave", and the "true sine wave".
Modified Sine Wave -The modified sine wave is not really a sine wave at all. It is more less a "stepped wave". It achieves voltage regulation by varying in width according to the battery voltage and the load. Thus, the wave is not as smooth as a sine wave. The quality of modified sine wave inverters should not be underestimated. They are highly capable, and (by narrowing the waveform) they save energy when running only small loads, as happens during most of the day in a typical home. Modified sine inverters have been successful in many thousands of remote home, RV and marine systems since 1986.
True Sine Wave - Also known as Pure Sine Wave, is the most reliable waveform and provides power almost identical to a standard wall outlet. The power produced fully assures that your "sensitive loads" will be correctly powered, with no interference. Some appliances are likely to require Pure Sine Wave including digital clocks, battery chargers, light dimmers, variable speed motors, and audio/visual equipment. For these reasons, true sine wave inverters can be more a more expensive choice.

What are the differences between 'Online' and 'Offline'?

Off-line (VFD) systems are usually low cost products designed for a simple one or two user PC installations, they offer little or no protection against most supply problems and really only give support for short-term power loss. The load is fed from the mains during normal operation, hence 'off-line'. On-line (VFI) UPS systems are regarded as 'high-end' and employ more sophisticated technology which uses a rectifier and inverter, hence 'double-conversion'. This effectively isolates the load from virtually all types of power supply problems.

What is the difference between "KVA rating" and "KW rating" of UPS?

The mathematical relation is kW= kVA *pf. where kW is active or useful power and kVA is the vector sum of active power and reactive power. The equation therefore is kW= kVA *pf

What is the Input Power Factor (p.f.) of the UPS at different loads?

Power factor is a function of phase displacement angle between voltage and current and distortion factor. It is calculated as a ratio of real power to apparent Power drawn by load. PF is low at lower loads and goes on improving at higher loads. PF is also lower at higher input voltage and goes on improving as voltage reduces. Input Power Factor is independent of type of load for double conversion technology.

How can I remotely monitor my UPS system?

There are two ways in which you can monitor your UPS remotely. One option is to install a wall mounted Remote Panel (MultiPanel) that connects to the UPS to a serial port on the UPS and offers the advantage of full digital metering (available for all UPS models - 400 m cable max and required 230 Vac UPS backed mains supply). The panel incorporate a multi function audible alarm with mute facilities and lamp test.
The alternative option is to utilise the computer network with our NetMAN network adaptors to provide full UPS status and measurement values via a web-browser with facilities to send alarms using email, SMS messaging, SNMP traps or directly to an existing BMS system. This device can also offer temperature monitoring and unattended server shutdown when combined with optional modules.

Can I add more UPS modules to the system when my load increases?

Yes, the MST, MPS and MHT ranges employ a plug and play parallel system that allows additional units to be added to an existing system at a later date. Additional UPS units can be added to either provide redundancy or extra capacity if the load increases. Sometimes it’s worth investing in additional switchgear early on so that more units can be accommodated much more easily.

Which one should I choose, Single or Three phase UPS?

Here are many aspects which affect the choice of module. Totally single phase units are rarely available beyond 20 kVA, above this size it is usually necessary to use a three phase input for the rectifier, even where the inverter output is single phase. When feeding this type of system via a generator it is important to remember that the bypass line will be single phase, demanding a higher current on one phase only. Larger units with three phase input/output are more easily distributed across generators and can also be used to feed single phase loads, and with good load balancing, need not be oversized