Talk:Uninterruptible power supply

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Is a rotary mechanical inverter a type of "rotary UPS"?[edit]

Does the rotary UPS section needs to be divided into sections? I'm seeing feedback from other editors that go in a different direction.

To me, an uninterruptible rotary UPS is essentially a flywheel and motor/generator. (The motor/generator can be the same device, because electricity freely converts back and forth to magnetism, as long as either the field coils are excited or permanent magnets are used.)

User:Arkayos is saying that no, a "rotary" UPS can also be a bank of batteries driving a literal motor and generator combination. As far as I can tell, this is basically just a mechanical implementation of the electronics called an "inverter", where DC input becomes AC output using an electronic oscillator, diodes to make intermittent DC, and capacitors for smoothing. Well, a DC motor driving an AC alternator does the same thing, but with moving parts.

But is it really a "rotary" UPS? As far as I understand it, the "rotary" aspect of a "rotary UPS" refers to the energy storage component, not that there may or may not be other spinning components that don't store anything (or don't store anything significant).

How big does a generator or motor-generator need to be, before its rotor's kinetic energy storage is considered a significant amount of ride-through energy storage?

DMahalko (talk) 18:39, 2 April 2012 (UTC)

I have a different impression of what happened: different rotary products have confused the issue.
Classic online rotary UPS has motor continuously driving a generator (possibly integrated) and an energy storage flywheel. When power dies, the flywheel continues to supply energy to the generator for a short time. That's the ride through. It gives a small amount of time for things to shut down normally.
The diesel rotary UPS uses the ride through time and some energy in the flywheel to start a diesel engine that takes over the role of supplying power by rotating the generator. The stored energy is chemical, so the UPS can supply hours of backup.
Then there are offline variations. What if the shaft isn't turning when the lights go out? Something (e.g., a battery) must supply power for an orderly shutdown or to fire up the diesel engine. That can take a lot of batteries.
The DRUPS section was also edited by compressed air battery proponents. Those proponents claim a compressed air battery can start a previously idle, low inertia, (rotary) generator within 300 ms (note: no rotation at power out and no mechanical ridethrough) to provide power in the short term (10 air cylinders can provide 20 kW for 10 minutes). (I suspect the electronics are a bit more involved; the generator is probably not putting out 60 Hz. A battery may be used for the first 300 ms.) A diesel generator may take over for the long term given the builders have a "Compressed Air Diesel Rotary UPS Systems (Air-DRUPS)".
I don't think rotary UPS necessarily implies significant flywheel energy storage, but I don't want to take a position on that issue without more sources. All rotating systems will have some inertia. The hybrid rotary UPS paper doesn't rely on an explicit flywheel, but it may still use some inertia when switching to the battery. The issue behind Arkayos' "fundamentally wrong" edit is that we need some sources to provide a definition of "rotary UPS". One position is that only rotating machines (motors, turbines, generators) are required; another position requires rotating energy storage. It's a definition, and it may have changed over time.
Arkayos' talk page statements seem sound and supported by the sole reference in the section. A motor generator / inverter could be used for line conditioning. The hybrid rotary UPS paper terms it a "rotary filter". Electronic inverters are probably still somewhat fragile. There are engineering choices about how to store energy (e.g., battery vs. flywheel) and how to use the battery: whether to use an inverter directly, an inverter and an AC motor, or a DC controller and a DC motor.
The simple way out here is to start tagging and referencing the statements in the section. If you find a statement you disagree with, then look for a reference that says it. If you cannot find one, then tag the statement with a cn template. Over time, the section should get better.
Glrx (talk) 19:19, 3 April 2012 (UTC)
Part of the problem seems to be that people are overlooking the word uninterruptible. If you have an emergency power supply that needs several seconds to start working after an outage, it isn't uninterruptible.
A basic non-online UPS doesn't even meet that definition, if we get really picky, since the inverter circuits aren't running all the time and only starts up when main power is lost, which is why some call it a standby power supply.
Though its startup time is extremely short, on the order of 25 milliseconds or less, so it's practically uninterruptible compared to say a diesel generator that needs cranking time of at least several seconds plus speed stabilization before the generator is actually switched in.
DMahalko (talk) 20:42, 6 April 2012 (UTC)
I went looking for a definition of a rotary UPS: "The rotary UPS is called “rotary” because rotating components (such as a motor-generator) within the UPS are used to transfer power to the load. The true definition of a rotary UPS is any UPS whose output sine wave is the result of rotating generation." (Schneider Electric p. 6.) That definition goes on to exclude some systems using flywheels as energy storage.
The industry seems to have a broad classification of static (no moving parts) and rotary.
Glrx (talk) 22:24, 7 April 2012 (UTC)
I've been working for a UPS manufacturer of such "rotary" UPS. They differentiate between static and rotary. As static UPS they describe UPS which do not comprise a Motor/Generator Unit and/or a flywheel. A rotary UPS comprise at least a motor/generator unit. Then the customer has the choice, with what kind of method he want to bridge over a short power failure (Battery or flywheel). A further option is the use of a diesel engine to satisfy longer power failures. In this case, the Motor/Generator is lying and coupled to a diesel engine, otherwise the Motor/Generator is standing. So, I agree to the paper of APC.
MarvTB (talk) 21:42, 20 August 2013 (UTC)

Unsourced Material[edit]

Article has been tagged since 2009 for needing sources. Feel free to reinsert below material with appropriate references. DonIago (talk) 22:18, 1 August 2013 (UTC)

Frequency variations[edit]

The voltage and frequency of the power produced by a generator depends on the rotational speed. The speed is regulated by a device called a governor. Some governors are mechanical, and some are electronic. The job of the governor is to keep the voltage and frequency constant, while the load on the generator changes. However, the governor does not respond instantaneously to load changes. This may pose a problem when, for example, the startup surge of an elevator causes the frequency of the generator to drift temporarily as the governor is adjusting to the new load, thus affecting all other devices powered by the generator. Many radio transmission sites have backup diesel generators—in the case of amplitude modulation (AM) radio transmitters, the load presented by the transmitter changes continuously and instantaneously with the signal level. This leads to the scenario where the governor is constantly trying to correct the output voltage and frequency as the load changes.

It is possible for a UPS unit to be incompatible with a generator or a poor mains supply; in the event that its designers had written the microprocessor code to require exactly a 50.0 Hz or 60.0 Hz supply frequency in order to operate, the UPS could remain on battery power, being unwilling to reconnect to the fluctuating input.

The problem of input frequency should not be an issue on a Double Conversion / online UPS. A UPS of this topology should be able to adapt to any input frequency, using its own internal clock source to generate the required 50 or 60 Hz supply frequency.


Modular UPS architecture (or topology) is a method designed to reduce cost and give UPS users flexibility in system configuration and use. Modular UPS systems consists of fixed control and power switching moldules. The battery storage element is modularized. Typical systems are designed to fit into one rack. Larger UPS system designed for large IT installations span multiple racks and consists of dozens to hundreds of modules. Battery storage “modules” are configured from one to as many as ten modules in typical medium size UPS system. Each battery “module” gives a fixed power storage capacity. One of the first companies to develop and release a modular UPS system was Gamatronic Electronic Industries LTD, an Israeli company that develops and manufactures uninterruptible power supplies, telecom power systems, control and management systems and customized power solutions. Gamatronics’ Mega V2 Modular UPS system is configured in one to twenty battery modulems. This gives the system a power capacity range of 25 kVA to 500 kVA.

— Preceding unsigned comment added by Doniago (talkcontribs) 17:23, 26 February 2014

  • User:Doniago removed the above unsourced material from the article and inserted here. I reformatted the insertion. Glrx (talk) 22:21, 27 February 2014 (UTC)

UPS for furnaces?[edit]

The recent ice storm has left many New Jersey and Pennsylvania suburban homes without utility power for days. Some homeowners have used outside gasoline generators. My question is whether there are UPS battery units which could keep oil or gas furnaces running, to keep homes at least warm enough to not have the pipes freeze, especially in hot water radiator systems?--DThomsen8 (talk) 01:03, 11 February 2014 (UTC)

Sorry, it’s not appropriate to ask about that here. See WP:NOTFORUM "talk pages exist for the purpose of discussing how to improve articles. Talk pages are not mere general discussion pages about the subject of the article, nor are they a helpdesk for obtaining instructions or technical assistance." Indefatigable (talk) 18:54, 11 February 2014 (UTC)

Should be updated to incorporate supercapacitors (ultracapacitors) as an alternative to batteries[edit]

Supercapacitors, or ultracapacitors are becoming increasingly common as an alternative to batteries as a storage component in uninterruptible power supplies. For example: those by Maxwell Technologies. Currently, the article makes no mention of supercapacitors as storage (except the reference I added in the intro paragraph). It should be updated to include such systems. --Yambu (talk) 14:37, 16 April 2014 (UTC)