Uninterruptible Power Supplies - Selecting the Right UPS

Why is there a need for power protection?
It has never been more important to maintain a continuous and high quality - clean - electrical supply. There is a continuing and increasing demand for electricity. National distribution systems are facing increasing pressure to meet demand and deliver power of constant quality. While the demand for electricity has been increasing and placing increased pressure on the ability to deliver quality power there has been a dramatically increased requirement for quality power due to the increasing complexity and wider use of computerised, micro-processor controlled and sensitive equipment.
Computers, offices, telecommunications, industrial control systems, as well as many other key applications and services, are totally dependent on the quality of the power which feeds them.
At any moment an AC mains supply can be subject to:-

  • electrical noise
  • high energy spikes
  • voltage or frequency variations
  • total power loss, micro breaks and other interruptions

For example an unprotected computer can suffer greatly at the hands of raw AC mains supply. Typical problems which may be encountered include memory and data corruption or loss, unscheduled shutdowns, interruption to critical operations, disk drive malfunction or damage.
The effects of such butchery to systems are both harmful to business and costly in terms of time and money - not to mention the sheer inconvenience to all concerned. Power pollution will downgrade the performance and shorten the life of any system exposed to the raw mains supply.

Power Quality Issues – Causes and Types
Power black-outs are not the main power quality consideration. The AC utility mains supply is polluted with spikes, surges and other disturbances generally referred to as electrical noise. It is a natural by-product of the distribution and use of electric power.
As the demand for power increases and decreases, the power supply companies bring generator stations on and off line. This process is usually known as Grid Switching. As the power providers attempt to carry the process off smoothly it can result in a brief dropout in power, followed by a brief surge as nominal power is restored.
Lightning strikes are also a potential source of power line noise and high energy spikes. Even when the strike is miles away, surges and spikes measuring thousands of volts may be injected into the power supply.
In general, much more electrical noise is created right in your own building / local area by noisy electrical loads. The start/stop operations of heavy duty electrical machines, such as air conditioners, lifts or welding equipment, and also normal office items, such as fluorescent lights, copiers, coffee makers, vending machines and even computers can throw back noise into the electrical system from which they operate.
These power quality issues are generally summarized by the following types:-

  • Power Failure or Blackout – a total loss of power
  • Power Sag  – Short term low voltage
  • Power Surge – Short term high voltage
  • Power Spike – Very high power surge for a very short time
  • Under Voltage or Brownout – Low voltage for an extended time period
  • Over voltage – Increased voltage for an extended time period
  • Frequency Disruptions – Frequency variation, distortion and line noise

What is a UPS?
UPS is the abbreviation for Uninterruptible Power Supply. In very simply terms it is a Power Conditioner with a battery. By adding the battery it is possible to offer protection against power failure / black outs.
Basically a UPS will consist of three key elements:-

  • Rectifier / Charger - takes the incoming AC supply and converts it to DC to trickle charge the DC battery and where applicable feed the inverter.
  • Inverter - takes the DC from the battery and where applicable the rectifier converting it to a regulated AC voltage to feed the critical load.
  • Battery - a collection of cells used to store the DC voltage.

Types of UPS
There are three main types of UPS (Uninterruptible Power Supplies)

The three types of UPS are:-

  • Backup – Standby – Offline UPS
    • Backup UPS generally provide a very low level of power filtration. They are usually installed where only battery backup is required in the case of power outages.
    • When the power fails the UPS detects the power failure and switches from mains power to its internal power source. This change over to UPS power is almost instantaneous.
    • These are an older style of UPS.
  • Line Interactive AVR UPS
    • Line Interactive UPS apply Automatic Voltage Regulation (AVR) which bucks and boosts the electrical signal so that it maintains a standard of +/- 240 volts. These UPS can apply this AVR to an input voltage variance before sending it into battery backup. This means that it can manage dips and surges without the battery being employed. Once the voltage dips below or surges higher than the specified range, the battery will take over, promising cleaner power for your sensitive electronic systems.
  • True Online UPS
    • The True Online Double Conversion UPS actually takes the AC current coming into the system, converts it to DC and then back to AC for the running of the protected attached equipment. This True Online system is the best because it insures that the power entering your equipment is totally independent of the power that is entering the building. This is extremely important if information and reliability are crucial to the operation. The True Online Double Conversion UPS present the highest degree of power filtration.
    • Benefits of True Online UPS include:-
      • These UPS protect against all types of power conditions.
      • It is the only true UPS. All other types are a compromise in offering a truly uninterruptible power supply.
      • A wider range of input voltages makes them suitable where input voltages vary too greatly for other types of UPS.
      • There is no lag or delay in a UPS changing over to backup power as the UPS is always providing the power from the internal power.
      • A True Online UPS is always under full load. There will not be the unfortunate surprise of having a UPS come under load in a power fail condition only to find that it can not handle the load.

A UPS can provide power conditioning and/or battery back-up. When the UPS runs out of battery power it can via the provided software manage an orderly shutdown of software programs and the computer so as to eliminate or minimize damage to equipment or loss of data. One or several UPS can be remotely managed via SNMP (Simple Network Management Protocol) cards installed or attached to the UPS.

What size UPS do I need?
This all depends on the load of your system. There are two ways that you can compute your load:

  • Add the amps of all equipment intended to be backed up and multiple it by 220 to get a proper voltage amp or VA rating. The UPS rating must exceed the VA total.
  • Add the watts of all equipment intended to be backed up and divide it by 0.7 to get a true VA rating. Again the UPS VA rating must be greater than the comprised VA rating.

Power Shield Uninterruptible Power Supplies

Office Uninterruptible Power Supply

  • AVR Line-interactive UPS
  • Power board style - 3 UPS and surge protected sockets & 3 surge protected sockets
  • Australian sockets
  • Connectivity - USB
  • 650VA

Defender Uninterruptible Power Supply

  • AVR Line-interactive UPS
  • Tower style
  • Australian sockets
  • Connectivity - USB
  • 650VA & 1200VA

Commander Uninterruptible Power Supply

  • AVR Line-interactive UPS
  • Tower style
  • Pure Sine Wave
  • Microprocessor controlled
  • Connectivity - USB & Smart Serial
  • SNMP option
  • Long run option
  • 1kVA to 5kVA

Commander Rackmount Uninterruptible Power Supply

  • AVR Line-interactive UPS
  • Rackmount style
  • Pure Sine Wave
  • Microprocessor controlled
  • Connectivity - USB & Smart Serial
  • SNMP option
  • 700VA to 5kVA

Centurion Uninterruptible Power Supply

  • True Online Double Conversion UPS
  • Tower style
  • Microprocessor controlled
  • Connectivity - Smart Serial
  • SNMP option
  • Extra wide input voltage range
  • Long run option
  • 1kVA to 10kVA

Centurion Rackmount Uninterruptible Power Supply

  • True Online Double Conversion UPS
  • Rackmount style
  • Microprocessor controlled
  • Connectivity - Smart Serial
  • SNMP option
  • Extra wide input voltage range
  • Long run option
  • 1kVA to 6kVA

Navigator Three Phase Uninterruptible Power Supply

  • Three Phase
  • True Online Double Conversion UPS
  • Microprocessor controlled
  • Connectivity - Smart Serial
  • SNMP option
  • 10kVA to 80kVA

Extreme Three Phase Uninterruptible Power Supply

  • Three Phase
  • True Online Double Conversion UPS
  • Microprocessor controlled
  • Connectivity - Smart Serial
  • SNMP option
  • 10kVA to 320kV

Free Quote Request