Uninterruptible Power Supply (UPS): Significant Hum with Online Versions? (1 Viewer)

[Jay Taylor]

The UPS units that I currently use for our home & shop computers are line-interactive versions. They provide power regulation & surge protection until a power outage occurs or the incoming voltage is out of tolerance. Then the UPS switches to providing AC from its internal batteries.

The line-interactive units produce only a small to moderate hum until they switch to battery power during a power loss, then the hum is quite noticeable.

I’m considering replacing a burned out line-interactive UPS with an online UPS that continuously provides power from the batteries.

For example: Tripp Lite Smart Online Model SU1000XL

Do online UPS units produce a more noticeable hum than the line-interactive UPS units?

Do any of you have experience using an online unit?

Pros? Cons? Suggestions?

 

[Scott L]

Sorry I can't offer any help but I've always been curious about getting a UPS. Other than a small amount of hum have you had any bad experiences with em?

 

[Jay Taylor]

Between our two shops & home we have seven line-interactive UPS units. Some are small (700 watt) some large (2200 watt) and one that uses two deep cycle marine batteries for backup!

I love having them, especially when I'm doing an invoice at my shop and the electricity goes out. I just continue with the invoice while the customer wonders why my computer still works when the lights are out.

About 12 years ago when we lost power, we would occasionally lose some equipment or end up with a corrupted database. Not any more thanks to UPS units.

My questions about online UPS units are just part of a continuing search to find the best solution to living with Oklahoma thunderstorms and power outages.

The bad: I just had a seven year old UPS unit smoke its circuitry. It wasn't the batteries but the electronics that smoked. Rather than having it fixed and then wondering if it's going to burn our house down I'll replace it with something new.

The online UPS units that I've checked out have better specs and a more pure sine-wave than the line-interactive units that I currently have. However if the hum is too loud then I'm not interested.

 

[Kimmo Jaskari]

No way to hide them away?

The huge UPS we have at work makes significant amounts of noise, and very annoying noise at that. I don't know about the smaller ones; we have a collection of 3000VA Powerware's that are double conversion online models but I've never run one of them outside the computer room (the computer room has significant noise in itself from computer fans etc so I can't tell how the UPS:es themselves sound.)

 

[Jay Taylor]

Thanks Kimmo. Unfortunately I don't have a room to hide them in to avoid the hum.

I'm guessing that an online model sounds like a comparably sized line-interactive model when the power is out. Which means it will always have significant hum when turned on.

Unfortunately I’m unaware of a location in OKC where I can check one out. I believe that Best Buy & CompUSA only have line-interactive models.

 

[Jay Taylor]

Off topic but:

Another thing to consider when buying a UPS is whether or not it is cold start capable. This would allow you to turn on the UPS when there already is a power outage to quickly power up your computer, check e-mail or whatever, then power down.

I could be wrong but I believe that most low cost UPS units don’t have a cold start capability. If the UPS’ specs don’t specifically state that it has cold start capability, then it probably doesn’t.

 

[Marko Berg]

Thanks, Jay. I appreciate the update. I'm currently in the market for a line-interactive UPS and this thread has some very good points that I need to consider while choosing a model.