Uninterruptible Power Supply (UPS) Installation

UPS System Installation – Step 1) Customer Site Survey – UPS engineers will visit your site to establish your exact requirements – your total building load, type of load and how long you need the system to run the in the event of a power outage. It may be that you only need a few minutes to provide an orderly shutdown of your IT systems – then a UPS only installation would be probably be the best choice, Any longer than a few minutes and a diesel generator installation service would be best.

UPS System Installation – Step 2) System Design – your UPS installation requires careful design to ensure the systems work together (UPS and generators should be ‘matched’). We can then assist with drawings and schematics. There are different types of UPS’s that are used for different applications.

UPS System Design Options: –

Offline UPS System – The off-line or standby UPS is the least common topology found today. It is a very inexpensive backup solution for personal computers used in the home or small office environment. It is available in output capacities from 100 VA to 3 kVA and will only provide basic battery backup and limited high-voltage transient protection.

Line interactive UPS System – The line-interactive UPS is the most commonly available. These devices range from inexpensive to moderately priced and are available in sizes from 100 VA up to 6 kVA. Typically designed to be used for backup and give limited power protection, they are primarily used for home and business-based computers, file-servers, and networks. In addition to battery backup and limited high-voltage transient protection, they offer limited output voltage regulation while being powered from the utility.

In the line-interactive design, utility power is fed to an auto-transformer having differing taps switched automatically by a utility voltage-sensing circuit. If the utility voltage drops too low, the transformer tap is switched to increase the UPS output voltage. If the utility voltage increases too high, another tap is selected to reduce the UPS output voltage.

Before the taps can be switched, most line-interactive designs require the UPS to switch to battery mode operation. After the tap-switch, the UPS then switches back to utility mode operation. Like the off-line UPS, when the utility and inverter switchover occurs, there is typically a 4 to 25-ms duration power loss at the output of the UPS.

In the line-interactive UPS, utility power is fed to an auto-transformer having differing taps that are switched automatically by a utility-voltage-sensing circuit.

The line-interactive UPS is not the best choice for a factory or industrial environment. Power-sensitive equipment would be connected directly to raw unconditioned utility power. Even though the UPS has basic output voltage regulation, the utility-voltage-sensing circuit can become a problem.

Additionally, the increased battery cycling of the line-interactive UPS results in greatly reducing battery life and costly unscheduled battery replacements. As with the off-line, the line-interactive UPS suffers from the same 4 to 25-ms output dropout, except the dropouts would be much more numerous due to the tap-switch regulation design.

Double Conversion On-line UPS System – The double conversion on-line UPS provides the highest level of power protection available. This UPS costs more than the line-interactive. They are available in sizes from 500 VA to well over 600 kVA. The on-line design provides a much higher level of power protection and is the best choice for protecting, networks, scientific, industrial, factory automation, military, aerospace, and other mission-critical equipment.

The on-line UPS uses active electronics to continuously regenerate new ac power while operating from both utility and battery sources. The incoming ac power is rectified to a regulated dc, removing voltage transients, noise, harmonics, and frequency-related problems. This regulated dc power is then used by the continuous duty inverter circuit to regenerate clean, new ac power. The output voltage regulation is a superior ±3%.

Incredibly, when operating from a utility or generator source, the ±3% output voltage regulation is maintained over the entire input 20% to 15% voltage range of the UPS. This provides total protection from sustained utility brownouts, overvoltage conditions, noise, transients, harmonics, and frequency drift. It is like installing a firewall between the sensitive equipment and the utility power.

Most on-line-UPS manufacturer’s ship their units configured with the UPS output frequency synchronized with the frequency of the incoming utility power. In applications where backup generator power is being used, this may not be desirable due to frequency instability problems inherent with some generators. Some UPS models provide a fixed output frequency. This prevents the frequency drift from passing through the on-line UPS.

As the on-line UPS incorporates a continuous-duty inverter circuit it can support extended or long-term battery-mode operation. Extended battery operation of up to several hours can be realized with the addition of extended battery bank options. Off-line and most line-interactive UPS designs use limited duty inverter circuitry and will not accept additional external battery banks.​

Rack Mounted UPS – Individual UPS modules to protect a server rack.

Centralised UPS – larger UPS supplying a distribution board that in turn supplies the server racks or other equipment.

Containerised UPS – for special applications where the installation has insufficient space or a temporary solution is required.

Bypass Switches – Essential to enable the UPS to be removed in the future for mainenance without needing to switch off the load.

Parallel UPS system – to give n+1 redundancy.

Space – UPS’s require space for access and maintenance – leave enough room for service access according to the manufacturer’s recommendations.

Floor Loading – UPS’s and Batteries are heavy so special consideration should be given to the structural integrity of the floor.

Cooling – UPS’s produce between 3% and 9% of their ratings as waste heat so it is important to handle this correctly.