APC Battery Backup Question - Please help

[Scream And Fly]

Okay, so I bought an APC BX1500 UPS and it seems to be working fine. Once in a while it will switch to battery power for a second or two then switch back to AC power (normal), but when it does, it seems to make a fairly noticable buzzing or hiss/buzz sound (in addition to the normal beep warning). It only does this on battery power.

Is that normal? Is also does that when I power it up on the test mode.

Thanks everyone,
Greg

 

[dderidex]

Both of mine do the same thing.

I presume it's normal.

 

[Scream And Fly]

Man, it kinda freaked me out when I first heard it. My smaller (500VA) unit never made that sound.

 

[jonnyGURU]

That's because the 1500 is a line interactive UPS and the 500 is just a stand-by UPS.

 

[Scream And Fly]

I hate to sound like a noob, but what does that mean? So, the buzzing on battery power is completely normal? What actually makes that sound?

Thanks (sorry for all the questions)

Greg

 

[Joe Fission]

If I'm not mistaken, the buzzing sound is the sound of the transformers turning battery power (24VDC for the BX1500 I believe) into 120VAC... it's completely normal.

 

[boostdemon]

yeah my 1500 used to do that too after being perfectly silent for years... then it got worse, and then it started flipping to battery power for no reason and eventually it wouldnt charge anymore.

 

[Scream And Fly]

So your 1500 was always silent on battery power?

 

[Joe Fission]

yeah my 1500 used to do that too after being perfectly silent for years... then it got worse, and then it started flipping to battery power for no reason and eventually it wouldnt charge anymore.

Sounds like you need replacement batteries.

 

[Scream And Fly]

Okay, one more question - would the buzzing be louder of the PC was running and drawing from the battery when the unit switched to battery power? In other words, the more draw, the louder the buzz from the transformer?

 

[Ice Czar]

They dunk the transformers/inductors used in power supplies and SPS\UPS into varnish during manufacture, to hold the windings in place. Every once in a while a part won't go the full way into the potitng tank or sometimes a manufacturer will forget entirely... the loose windings and loose transformer core will "dance around" a bit and cause noise.

This doesn't cause any reliability problems, but it can be annoying as fuck.

Does the sound change depending on what you're doing on your computer? if so, this is your problem.

color edit mine, yes as the current they are dealing with changes so would the frequency\pitch\volume

http://www.energyquest.ca.gov/how_it_works/transformer.html
http://science.howstuffworks.com/inside-transformer.htm

 

[AtomicFire]

I hate to sound like a noob, but what does that mean? So, the buzzing on battery power is completely normal? What actually makes that sound?

Thanks (sorry for all the questions)

Greg

Interactive:
Input power -> charging batteries\powering inverter -> protected power outlets
When the power goes out, the system is basically already running off the battery anyways so there is no switchover time.

Standby:
Input power -> charging batteries
-> power outlets
When the power goes out, the system has to switch over to the batteries (a few miliseconds, makes that "click" sound).

 

[Ice Czar]

Line Interactive = Standby they are one and the same class

youve confused Line Interactives with Onlines

Line interactive is a more consumer friendly term than Standby
since Standby just seems to be a slacker neverdowell just in case useless kind of term

How The Line Interactive Uninterruptible Power Supply Tackles Power Problems

Output Waveform

When the mains supply is present it is filtered and stabilised by the UPS and passed through to the load. The output waveform from the inverter is normally either a true sinewave or pseudo sinewave (dependent on UPS type). The term pseudo indicates a step-wave or square-wave output. The step-wave or square-wave output may not be suitable for all types of loads.

Sags and surges

The load is supplied by the incoming mains supply which is filtered and stabilised using the automatic voltage regulation device; whilst the inverter remains switched off (provided that the input window is not exceeded). The battery charger continues to convert the mains AC into DC to charge the battery. If the sag or surge exceeds the input window then the inverter is switched on to maintain the required output voltage tolerance.

Transients, spikes and electrical noise

The output to the load is filtered by the Electro Magnetic Interference (EMI) and noise filters within the UPS. These filters attenuate (reduce) the incoming transients, spikes or electrical noise down to an acceptable level. These disturbances will not be completely prevented from passing through to the load and any large voltage spikes or transients that may exceed the input voltage window will cause the UPS to switch on the inverter.

Brownouts

The output from the UPS is maintained to within a specific window; therefore the UPS will automatically adjust the transformer tap settings dependant on the incoming mains supply voltage. Once the incoming mains supply exceeds the specified window, the UPS switches on the inverter to continue to supply power to the load.

Short duration mains failures

During short duration mains supply failures the UPS will supply power to the load using the inverter. However constant short duration supply failures can lead to unnecessary discharging of the battery.

Long duration mains failure - blackouts

The load is supplied by the inverter which is switched on the moment the incoming mains supply fails. Some line interactive UPS have a battery extension pack capability, that enables additional battery packs to be connected. This in turn extends the autonomy of the UPS (battery operation time). The only other alternative is to oversize the UPS to achieve a longer runtime as most line interactive UPS are only provided with a short autonomy of approximately 10 minutes.

Recharge

The battery charger will generally recharge the battery to 80% within 8 hours to provide sufficient battery autonomy ready for the next supply failure. Where it is possible to extend the battery capacity (typically from 2kVA and above), additional battery chargers can be added to maintain a reasonable recharge time. The internaly charger is not normally capable of supporting additional packs as the UPS is built to a tighter price specification than an on-line UPS.

Standby UPS

The standby UPS delivers the utility voltage as is — or after some conditioning — to its output and from there to the load via relay contacts or a solid-state switch. Once it detects a utility voltage failure (drops below some threshold), the relay transfers the load to an internal inverter, which converts the voltage of the internal battery to ac voltage of magnitude and frequency similar to the utility. The battery now starts a slow discharge and its voltage gradually drops. If the utility voltage reappears quickly, the load transfers back to it by the relay. At this time the load loses power, but prior to cut off the alarm circuitry within the UPS alerts the user by visual alarms and audio beeps starting at one every few seconds and progressing to rapid beeps as the UPS reaches cut off. The UPS delivers relay contacts or electric signals to the user — facilitating orderly shut down. These alarm signals communicate to the host system via RS-232 or RS-485 protocol, enabling automatic control over the host system's operation. Sophisticated UPSs provide a screen display (in an MS Windows environment), which appears on the host system monitor, advising the user how much time remains on battery. Some “Smart Software” is also available to program the orderly shutdown of the host system without human intervention — a useful feature if the system is unattended when power failure occurs.

The majority of standby UPSs in the market are underrated in power — intended for a short operational time on their inverter. They also deliver a quasi square-wave ac voltage to the load. This allows a substantial cost reduction, since it's much easier to convert battery voltage (12V, 24V, or 48V) to quasi square-wave than to a pure sinewave. This also contributes to making the unit smaller, lighter, and more efficient, and doesn't seem to bother some appliances — including personal computers. Because they are relatively inexpensive, portable, and simple to use, the standby UPS is most suitable for consumer applications, such as to back up computers, monitors, and printers. Most also include protection against utility transients and lightning. Certain models provide voltage regulation on an ongoing basis by some tap control on an input autotransformer. All of these features help to enhance computer protection. Fig. 1, on page 36, shows a 500VA UPS used for computer back up.

Despite these advantages, however, the standby UPS suffers from a major disadvantage. A relay makes the transfer of load from utility to the internal inverter, and creates a disruption of 5 ms to 10 ms in current flow to the load. Fortunately, most personal computers (and some electronic systems) can tolerate such a disruption without a detrimental effect to performance. Therefore, inexpensive standby UPSs ranging in price from $50 to $120 are used by millions of users of personal computers all over the world.

Standby UPSs are available in the range of 300VA to 500VA for office use, and up to 2KVA to 3KVA for workstations and large servers. Some are available with a step wave shape resembling a sinewave. Large standby UPSs employing ferroresonant topology provide emergency lighting for buildings.

vs

an Online UPS

In the online UPS, (Fig. 2, on page 39) the internal inverter operates at all times and its output feeds the host system. As a result, the inverter must work nonstop even while utility voltage exists. In addition, online UPSs usually provide sinewave voltage on their output terminals, and that obviously complicates its circuitry and adds to its volume and cost. Therefore, the price of an online UPS is three to five times that of a standby UPS with the same power rating. The internal inverter runs on the battery continuously, and the battery is charged from a high power converter (charger) within the unit while running on utility voltage. Hence “double-conversion UPS” is frequently used to describe an online UPS.

A simpler method runs the inverter on the rectified voltage of the utility — like an SMPS — instead of on the battery. This enables the charger to be much smaller, since it slowly charges the battery over 10 hr to 12 hr. When the utility drops, the battery takes over the dc rail directly or via dc-dc converter, causing the operation of the inverter to continue without interruption. The two main features of the online UPS are its sinewave output and its true uninterruptible operation. Some online UPSs contain an input or output power transformer, which provides galvanic isolation from utility — a desirable feature for safety and noise reduction. However, due to cost considerations, most low power (1kVA to 5kVA) UPS, especially those made in the Far East, have no isolation, and you use the input neutral line also as the output neutral.

Online UPSs cover the power range of 500VA to several hundred kVA. Most have an internal battery adequate for 5 min to 15 min interruption. Some high power UPSs are equipped with a separate cabinet for the battery, and provide backup time in the hours. For those requiring very long backup (12 hr to 48 hr), the battery bank becomes huge in size, compared to the UPS itself, and a generator UPS combination may be a better choice. Some online UPSs include input power factor correction and have elaborate front panel display and communication software. This allows remote monitoring of the UPS and permits gathering of useful data on ongoing basis.

Many online UPSs have a solid-state transfer-switch (SST), which enables load transfer to the utility if the UPS fails. The transfer also permits maintenance work on the UPS while temporarily feeding the load from the utility. The transfer switch enables the load to be on the utility at start, and only after the initial current surge subsides does it transfer the load to the inverter. A phase-lock-loop (PLL) circuit within the UPS ensures “seamless” transfer of the UPS by this SST between utility and inverter and vice versa. The PLL circuit “locks” the frequency and phase of the UPS to the utility at all times.

The main advantage of the UPS is being a stand-alone unit, which can be added arbitrarily only to those systems or loads that cannot tolerate a utility interruption. The end user, who must pay its cost, (about $1 per VA) makes the decision whether to use the system and chooses the type, model, and make. Also consider the outlay, otherwise the resulting UPS could be incompatible with the system's needs.

why one was making more noise than another likely had to do with the components and circuit design, the transformers involved

 

[jonnyGURU]

For people that prefer diagrams: http://jonnyguru.com/images/UPS.doc

 

[Ice Czar]

and for those Inquisitors that are photochopped challenged

here you see why the Onlines are a different "Class"

Black is the "normal" path and grey the "fail" path
Onlines fail over to the mains and become just surge protectors
normally they are mixed with backup generators

the opposite of the other two that fail over to the batteries
onlines are constantly on and only "fail over" when they actually fail
the other two switch over in the event the mains fail

 

[jonnyGURU]

Cool... but you're missing the little Chinese captions that I have no idea what they say.

 

[Scream And Fly]

Awesome information - THANKS so much guys!!!

 

[Ice Czar]

a little chop edit to highlight why Standby and Interactives are the same "class"

as far as the Chinese notation it was just a Lo Mein Recipe I assure you