Home Page - Power Protection - Uninterruptible Power Supplies

Uninterruptible Power Supplies

Is it really possible to make use of an inexpensive computer-grade UPS in the Home Theater?

Computer-grade uninterruptible power supplies are reasonably priced, surely cheaper than 'home-theater-specific' power centers. The purist may not agree, but if budget is an issue, a computer-grade power protection solution may very well represent a better alternative than a cheap surge protection power strip.

A Quick Guide to Home Theater Design

Discover how to research, design, and build your own Home Theater.

by Duncan McClelland
More information HERE.

Updated: 26^th April 2009

Cyberpower CP1500AVRLCD 1500VA/900W line-interactive UPS

Would you consider a computer-grade uninterruptible power supply as a power protection solution in the home theater?

In their quest to protect sensitive and expensive home theater gear, many system owners do not foresee the option of using computer-grade power protection as part of a possible solution to their needs.

It is as if uninterruptible power supplies and surge suppressors designed to protect expensive and sensitive computer equipment, will do a poorer job in the home theater.

This article investigates the possible use of a computer-grade uninterruptible power supply as part of a power protection solution for AV systems.

There is a lot of controversy surrounding the use of computer-grade power equipment in the home theater.

Yet these systems come at a significantly cheaper price-tag than audio-grade counterparts; therefore, for the budget conscious, a computer-grade power protection solution may represent a possible alternative.

In reality, this is a technically acceptable approach - as long as one is aware of possible limitations that may arise when making use of equipment other than for its original designed purpose.

The Computer-Grade UPS Power Protection Solution

From a budget perspective, for the money you pay for a suitable 'home theater specific' high-end surge suppressor, you can get a good quality 'line interactive' or better still an 'online' computer-grade uninterruptible power supply (UPS).

A UPS is basically an AC Voltage Regenerator but with added battery backup. The electronics involved are very much similar in principle. However, not all computer-grade uninterruptible power supplies support the desired functionality to act as a suitable replacement for an AC Voltage stabilizer/line conditioning solution in the home theater.

Different UPS Categories

It is important to highlight the differences between the different type of uninterruptible power supplies available for home PC use. Surprisingly as it may seems, some of these uninterruptible power supply solutions will not provide the much desired AC line conditioning and power protection for your electronics in the presence of a 'normal' AC mains supply.

Having an understanding of the different UPS categories is therefore important if you are seriously considering the cheaper computer-grade UPS option as part of a home theater power protection solution.

The main Uninterruptible Power Supply categories include:

Type 1: Standby UPS

Type 2: Line-Interactive UPS

Type 3: Online UPS

'Standby' Uninterruptible Power Supply

A standby UPS system, also known as an off-line system, powers equipment directly from the AC outlet. In the event of either a complete power failure, or a variation in the input AC voltage that exceeds pre-set limits, then the UPS kicks in and the unit goes to battery operation. However, there is a small delay in the process - in the region of a few milliseconds.

These are the low-cost UPS's. Batteries are charged as long as there is main power available. These units do provide some protection against AC supply voltage fluctuations that fall outside the pre-set operating range, and would also include some minimal protection against spikes and switching transients. But take note that the power protection offered by these inexpensive systems is not on par with neither with power line conditioners nor with true surge protectors.

The 'standby' uninterruptible power supply is the least suitable for use in the home theater - it do not provide sufficient protection against voltage sags or burnouts (drop in voltage in an electrical power supply) and overvoltage surges as often these units allow for a too wide a range in AC supply fluctuations before the battery back-up kicks in. And cheaper UPS systems do not include adequate line noise and surge protection that should always be present irrespective of whether the UPS is powering the load on battery backup or direct from the mains.

'Line Interactive' UPS

A line-interactive UPS system differs from the cheaper standby type in that line interactive systems provide a voltage boost on sags without accessing the batteries. These are hybrid devices that offer a higher level of performance by adding better voltage regulation and filtering features to the standby UPS design.

The Cyberpower CP1500AVRLCD 1500VA/900W Uninterruptible Power Supply pictured above is one such type of line integrative UPS. The CyberPower is designed for mid to high-end computer systems and features dynamic line conditioning with automatic voltage regulation in addition to surge/spike protection and battery backup in the in the event of brownouts or total power loss. It is also equipped with full phone, fax, Ethernet, network, DSL protection as well as RG-6 coax surge protected connectivity (DSS, cable modem, satellite, cable TV). And all this is backed up by a Connected Equipment Guarantee of up to $500,000.

These systems would typically make use of a 'tapped' or a 'ferroresonant' transformer to maintain the required output voltage. The transformer provides voltage regulation and minimal power conditioning for disturbances such as electrical line noise.

This setup allows for continuous line conditioning, increases battery life, and reduces electronic noise. These units do provide some surge protection, though again, the surge protection provides is often not on par with a dedicated surge protector device.

As with the standby-type uninterruptible power supplies, complete elimination of line noise and frequency variations works only when the unit switches to battery operation. In addition, these systems are not very much effective against unstable frequency variations and sudden current changes.

'Online' Uninterruptible Power Supply

An Online UPS system differs from the less expensive line interactive UPS system in that the online system provides the highest quality power protection.

This is done via a double power conversion technique; the online UPS takes incoming power, converts it to DC, conditions it, and converts it back to AC. In such a setup, there is no delay to switch to battery.

Double conversion systems provide the same benefits of a standby UPS in conjunction with a line conditioner, at a price that is lower than buying the two components separately.

These systems offer complete protection and isolation from all types of power problems - power surges, high-voltage spikes, switching transients, power sags, electrical line noise, frequency variations, etc.

It is also the only type of UPS that is capable of delivering TRUE sine wave power even in the presence of the AC supply. True sine wave represents the optimum power for most AV electronics - as it only delivers the 60Hz (or 50Hz) voltage with no presence of unwanted harmonics on the AC line feeding your gear.

In view of the higher expense, increased weight, and size associated with online UPS systems, use of these uninterruptible power supplies is normally restricted for critical applications, high availability servers, etc. However, in view of its capability to deliver TRUE sine wave power output, it also represents the ideal UPS solution to use as part of a power protection system in the home theater.

Unfortunately, the 'online' UPS is the most expensive of the trio, yet it represents the ideal solution in that it is equivalent to having an AC power line conditioner but with the added advantage of a battery backup.

Is it really a 'No-Go' Solution?

Noise on the line: For the purists in audio and video systems - the use of a computer-grade UPS is simply a no-go approach. They would argue that uninterruptible power supplies designed for computer use might add more noise and distortion in the audio band.

To a certain extent, this may be true in that computer-grade power protection gear would normally incorporate EMI/RFI high-frequency noise filtering only and would not normally filter out any AC harmonics present on the line.

It is also a fact however, that even most mid-range priced power line conditioners designed for home audio, would most often fail to some extent in this respect. Filtering of noise in the audio spectrum is far from being a straightforward job.

But there is even more to the issue of noise and filtering of unwanted AC harmonics on the line. Most of these UPS would deliver a 'stepped output' instead of a pure sine-wave. The stepped output is typical in digital circuits and leads to a simplified inverter output stage on the UPS.

Unfortunately, the 'stepped output' is a good source for higher order harmonics that would appear across the UPS output. These added harmonics are in effect an added source of noise that would find its way into your AV system if not filtered out.

Surge protection: One should be aware that although computer grade uninterruptible power supplies would normally incorporate some surge suppression on their AC input, yet the surge protection available is in most cases far from adequate.

Main advantage of a UPS

While the 'off line' UPS does not really provide much added value in home theater power protection, yet the use of 'line interactive' or better still, 'online' UPS systems, would guarantee a regulated AC power output independent of the fluctuations or waveform distortions on the AC power line feeding your system.

Protection against power line fluctuations in the home theater should not be underestimated. Fluctuations on the AC line can turn out to be a serious problem for any home theater setup, while prolonged fluctuations may lead to overheating and occasional damage.

Fluctuations by as much as ±10% of the nominal AC line voltage may cause a 200W amplifier to deliver only 160W. Large power amplifiers found in subwoofers, multi-channel power amplifiers, projectors, and RPTV systems, are extremely power hungry, and therefore fluctuations of this magnitude on the AC line would mean a dimmer picture for a projector during a bright scene, or a significant loss of power for an amplifier during a loud passage of music.

Concluding Remarks

Surely, suitably rated computer-grade uninterruptible power supplies represent a possible power protection solution for any home theater set-up. Computer vendors can provide reasonably priced protection solutions that may represent a better value to your requirements.

It is all a question of analyzing what you will get when investing in a computer-grade uninterruptible power supply as against an equally-priced protection system specifically designed for home theater use.

We are not saying that AC regenerator based systems designed for home theater such as the 'Monster Cable MP AVS 2000 SS Signature Series Automatic Voltage Stabilizer featured elsewhere under this section or the Furman IT Reference series of dedicated protected power sources for home entertainment use - such as the Furman IT-Reference 15i 11-Outlet Discrete Symmetrical AC Power Source, are not worth the investment. These products are capable of delivering remarkable results, exceptionally clean power, and come with a level of build of build quality that is difficult to match, but...

Surely, there is a price to pay - expect to pay anything between $1,500 and $3,000 for these products.

It is all a question of available budget - if you are working within a tight budget, the computer-grade UPS solution may be the way to go.

It is possible to improve on the 'raw' computer UPS solution and still ends up with a less expensive alternative to the 'dedicated' home theater AC Regenerator.

You can always include additional filtering to the output of a computer-grade uninterruptible power supply. Inexpensive units such as the $30 Monster Cable MP HTS800 Home Theater PowerCenter HTS800 would provide enhanced surge suppression on both the AC line as well as protected connections for the phone line and the coax TV input.

Tripp Lite HT10DBS Home Theater 10 Outlets 3570 Joules RJ11/45 Surge Suppressor

And for a little bit more, you can easily get significantly improved surge protection. The $80 Tripp Lite HT10DBS Home Theater 10-Outlet power strip come with a 3570-joule rated surge suppressor, and incorporate multiple-line coaxial, phone/modem, and even network surge protected connections.

The use of a surge protector such as the Tripp Lite HT10DBS in tandem with a computer grade uninterruptible power supply will surely represent a cost effective and highly efficient power protection solution for any home theater setup.

Power Protection Solutions @ amazon.com

Amazon carry a vast range of power projection gear for your audio and video applications, including surge protectors, automatic voltage stabilizers, uninterruptible power supplies and power line conditioners from top brands like Monster Power, Panamax, Belkin, Tripp Lite, and APC.

You can search the amazon storefront without leaving our site by using the amazon search box below; your search results will appear here under.

Amazon.com Widgets

Power Protection Guides