Choosing a UPS for the system

September 5, 2017
 by Paul McGowan

10 comments on “Choosing a UPS for the system”

  1. Can we say modified sine wave? Or are we trying too hard to sound too smart ?
    So we managed to get out the sinewave word , but what about the P ?
    What about batteries? And inverters ? And the switchover time? And hpw to keep the batteries charged ? How does a person make sure the wave is ” nice and smooth” ? Hook it up to our oscilloscopes ? I mean , really . ..

    1. Sorry, it wasn’t more complete, though the truth is (from my perspective) a well-designed line interactive UPS, like those from APC for example, require little thought and even less maintenance. I would recommend a check on the batteries about once a year.

      With respect to switchover time, my experience is that most modern UPS of any quality have this issue in hand and while this used to be a problem worth worrying about, it isn’t any longer.

      Perhaps I am too comfortable with simply buying APC UPS products. Plus, I don’t actually use them in two-channel systems. The occasional power outages in my area are so rare there’s really no need.

  2. 1. I use a single P10 to protect my entire system which includes a PLINIUS SB301, an Ayre preamplifier and DAC, and an Aurender file server. (Sorry Paul, the only PS Audio product I have is a P10 – but I am very happy with it).
    2. I live in an area where there are frequent lightning strikes, quite a few brown outs, and at least one (perhaps more) outages (often brief) per month. As Paul states I feel that the P10 does a good job in protecting the system against brown-outs and lightning strikes (again, it is obvious that a direct hit cannot be protected against).
    3. I selected an Aurender file server because the philosophy is “a dedicated box to file serving with no other function in mind”. However, when there is a power outage, the system goes through a hard disc recovery routine which takes at least 10 minutes and can be more. However this raises the spectre of losing the hard disc entirely due to a power outage. I suspect that in digital audiophile systems this is an area where protection from power outage is of benefit. One backs up hard discs but that is like testing the emergency brakes on a high powered sports car – you never want to use the back up.
    4. There seem to be two choices.
    (a) Go with the heavy duty (2 kilowatt) battery back up for the entire P10 as discussed above OR
    (b) Go with two battery back ups – a lower power one for digital components (or file server). Connect the digital electronics (or the file server alone) to a separate (smaller than P10) with a correspondingly lower wattage UPS for the digital (or file server) portion of the system.

    A good quality 2 kw generator (on a brief layman review on the internet) does not seem readily available in an attractive domestic format.

    This could raise a sub-question of whether it makes sense to separate the digital component power supply from the analog units in a system.


  3. My details may be a little muddled here, so please bear with me. I had tried a Smart UPS with my desktop system because it produces a sine wave when on battery…. But, had to take it out because it introduced too much noise when not needed for back up. So? With a line interactive UPS? It will only kick in when the power is out? Will not introduce noise into the line when not needed?

  4. There are several types of UPSs. One type is off line. It doesn’t pick up the load until there is a power failure. There is a brief interruption for the load when the UPS switches from utility to battery backup power and back again. This can be disastrous for electronic data processing equipment since it can crash during the interval. Where dual pathing for data processing equipment is not available for legacy equipment, two alternate sources of power are switched by a fast solid state switch called a static transfer switch. Is it fast enough? The answer is ????? It depends on various factors.

    Another type is the line interactive type. This is the cheap type you buy for your home PC. It compares the incoming utility signal quality with a reference local sine wave oscillator and uses battery backup to correct the difference. It can have up to 40% harmonic distortion.

    The best UPSs are double static conversion types. They rectify incoming AC to DC to charge batteries and power an inverter to generate AC. When utility power fails there is no interruption of output power. Harmonic distortion is ususally 5% or less. This is the only kind for use in data centers that must operate without interruption. They are also the most expensive. The largest single phase unit I’ve seen is about 10 KW. Most are 3 phase for industrial use. I’ve installed them in laboratories for the most sensitive scientific instrumentation for many industries and they never fail to get the job done without impairing the performance of the equipment. As much money as I’ve spent on wire, I’ve spent far more on UPSs. The largest single unit was 1.6 million watts. Usually smaller units of up to 500 KW are connected in sometimes complex networks with a total capacity of many tens of millions of watts.

    My favorite brands are Eaton, Emerson/Liebert, and Mitsubishi. APC is not on my radar screen.

    A UPS seems like overkill for this problem. I don’t think there is much risk of damage to audio systems when power turns off. If there is a risk it’s when the power comes back on especially if it flickers. A much cheaper solution is an undervoltage release circuit breaker. When power drops below a preset voltage the breaker opens shutting down the load. You can turn off your equipment, reset the circuit breaker and turn the system back on again. If you have brownouts or voltage dips as I do when my central HVAC compressor starts up you can have nuisance trips. Have your electrician buy a “unit breaker” of this type and a box. He can fabricate it as an extension cord between your wall outlet and your equipment. This is much more convenient than installing it in your circuit breaker panel. Popular brands are Square D, GE, Eaton, and dare I say it, Siemens. You won’t find this at Home Depot or Lowes. It will have to be purchased through an electrical equipment supply house.

  5. I do not bother with UPS’s as blackouts and brown outs here can run into days (3). When we first moved to “The Hills” as the locals call the general area. We would suffer an outage every two weeks which generally lasted for a couple of hours. This was before the days of internet.

    As electricity suppliers changed and went privatised and maintenance crews were diminished. With continuous improvement over the last 26 years we suffer a blackout once every three months. More during winter and less during summer. This might ring alarm bells through audiophiles what I put my equipment through out here in the bush. I ring the power provider and if they advise that power will be out for 2 hours to days. I fire up the petrol generator with all its harsh noise. It supplies power to all power points and not to the lighting circuits. The theory is when the light come back on we can change over power at the switchboard from generator to Mains. All is good in the land of the Dandenong mountain range east of Melbourne. I have noise suppressors on all fragile electronics and trust in this.

    The generator supplies power to all power points, lamp stands, wifi, computers, Plasma TV, two fridges and a gas central heating system all of my own design being an electrican. I know the generator is noisy though only gets used half a dozen to a dozen times a year we have only had one modem failure in this time.

    I would like a sine wave greater and they are becoming more available. But I will stay with what we have at present.

    Mitch from Oz.

  6. hi paul, i once had a really unpleasant experience with a power outage. a car struck the transformer (i think) in my neighborhood which took out the power. no problem there until they powered up the neighborhood. the resulting power surge took out most of my NAD 7020 receiver-all but the line stage. the tuner and phono section were dead.

    as the power came on, every light bulb in the house doubled in brightness and then went POOF. gone. my wife’s computing typewriter also died and required an $80 repair. the power company denied responsibility for everything.

    what would have protected my electronics?

    1. Sure. The new power comes back on with a fury! Most reasonable power conditioners and surge protectors or Power Plant would have likely done the job. Inside they have an MOV clamp that should protect from such surges. Left plugged into the wall unprotected that’s when you get in trouble.

  7. This was a very helpful video.

    During winter storms it is not uncommon to have power flicker multiple times per hour. Things dropping out are sort of an irritant, its that immediate repower that makes me cringe.

    I have a APC UPS that, now that I’ve replaced the battery, keeps things running and I can manually power everything down if power doesn’t return.

    My new concern was that by adding tubes into my mix I was going to be flirting with danger.

    If I understood correctly, by getting a correctly sized Pure Sine wave, line Interactive UPS like an APC I can relax when the power flickers and bursts back.

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