Line Conditioner and UPS 2999

Roby has provided part of the story - why UPS manufacturers quietly recommend you not connect line conditioners or surge protectors to UPS outputs. Now more of those untold facts. The naive actually believe (because they don't first read manufacturer specs) that a plug-in UPS typically outputs a pure sine wave. Maybe if the UPS costs $500 retail. Meanwhile sales brochures use many expressions such as modified since wave - which means nothing. Power out of that UPS can be so dirty that it can even damage some small electric motors - for the same reason one should not use line conditioners. Let's look at the output of this 120 VAC UPS when in battery backup mode. That's two 200 volt square waves with up to a 270 volt spike between those square waves. This is a modified sine wave. An expression nothing more than a sales gimmick so that the naive will *buttume*. Pure sine waves is just another gimmick expression for electricity that is still not as 'clean' as what enters on AC mains.

Electricity so 'dirty' as to harm some small electric motors. And this is also called a computer grade UPS? Yes. Computers are so resilient that the 200 volt square wave is not destructive. 'Computer grade' means even 'dirtier' electricity is permitted - no matter what fancy 'sine wave' expression the color glossy sales brochure puts up.

Second, that UPS sales brochure also claims surge protection. Correct. They claim protection for one type of typically nonexistent transient. That is enough for others (such as some posters here) to buttume UPS provides protection for ALL types of transients. What does the UPS manufacturer forget to mention? UPS does not protect from the typically destructive type of transient. Even worse, the UPS could make transient damage even easier to an adjacent and powered off computer. Again, when will they first read manufacture specs? Well, good luck. Plug-in UPS manufacturers now make those specs all but impossible to obtain. Then the naive believe subjective expressions in a sales brochure is a specification sheet.

They naive may even claim a UPS will clean or condition electricity. In reality, the UPS connects a computer directly to AC mains when not in battery backup mode - again as made obvious from that oscilloscope observation.

Will that UPS stop, block, filter, or absorb what 3 miles of sky could not? That is what some here buttume. In the real world, surge protectors do not stop, block, etc destructive transients. They connect such transients 'less than 10 feet' to earth ground. So where does the UPS manufacturer discuss earthing? He does not. Manufacturer avoids all mention of earthing so that the naive will rush to conclusions about the ineffective surge protection. Manufacturer does not claim effective protection. If they short you on facts (where are the spec sheets), then others will promote mythical conclusions.

That UPS contains exact same protection found in power strip protectors - albeit typically less. How do you know both to be true? The UPS has a joules rating. Notice how pathetically small that joules rating is. Why? They don't claim effective protection. They claim some (trivial) protection - and hope the naive will promote the product as a surge protector.

First, don't worry about line conditioning. Computers, if properly constructed, are some of the most robust electrical devices in the home. This may not be true if a computer was constructed by a computer buttembler who does not know how electricity works AND who buys power supplies only on price (does not even know of essential functions that must be in a power supply and therefore can double the power supply cost). IOW worry far more that a computer power supply might be missing critical functions.

Second, how to identify an ineffective protector. 1) No dedicated connection to earth ground. 2) Manufacturer avoids all mention of earthing.

Third, the UPS serves one function - to protect computer data from blackouts and extreme brownouts. UPS does not provide computer hardware protection. Protection that should already be inside that power supply anyway.