Surge Protectors (TVSS)
Originally Posted by Felgar
I'm just generally confused about surge protectors, voltage regulators, power conditioners, and UPS's.
are used to eliminate transients (very short-term voltage spikes). These spikes are generally caused by switching transients (> 80% of them), but can also be caused by nearby lightning strikes. The most common culprits in residential applications are capacitor-start motors and switching power supplies. In commercial buildings, VFDs are the first thing to look for. A plain-jane TVSS does nothing to control steady-state voltage, and provides no low-frequency filtering, per se. Many high-end TVSS products ('series protection') bundle low-frequency filtering into the package.
The whole-house units are great for protecting from utility line transients from LTC switching and lightning, but you need to also provide point-of-use protection to absorb transients generated by equipment in your house. Both are a must if you have any significant amount of expensive gear. It is important, though that you have a unit which provides a SINGLE protection point vs. ground for cable, antenna/satellite, phone, and power. The reason? Let's say you have a power-only TVSS. If you take a lightning hit that is strong enough to lift the local ground level, then the phone line will still be at the original 0 V, while the power ground AND hot may instantaneously rise by 800 V or so. Although the TVSS clamps the two of them to a maximum of 140 V, without clamping them to the cable and phone grounds as well, you are still subjecting your gear (cable/DSL modems, satellite/cable recievers, etc.) to the 800V potential - bad things happen.
BTW, TVSSs are sacrificial, i.e., they degrade over time as they absorb transients, eventually becoming ineffective. Most of the good products provide indicators that show when a TVSS is used up and needs replacing.Voltage Regulators
actually control the steady-state voltage of your line. There are several methods of doing this; some will unfortunately induce transients themselves. Most houses don't really need these, because the utility regulates the voltage on the line with automated tap-changing voltage regulators; unless you have actually seen an excessively high or low voltage (from being at the beginning or end of a transmission line), this is probably a waste of money.Power Conditioners
are loosely defined - this term is used to mean lots of things, and is not controlled by UL standards in the same way as TVSS and UPS standards are. In general, though, this term is used to mean some sort of combination of TVSS and low-frequency foltering.UPSs
are lumped into several categories, but all of them continuously charge lead-acid batteries (generally VRLA), then use the batteries to provide backup power when the line voltage fails. They have three main sections: the Rectifier, whcih takes the AC line voltage and converts it to DC, the DC Bus, which is where the batteries are connected, and the Inverter, which changes the DC into the AC output power.
The cheap ones are 'Line-Interactive'. This means that they do absolutely nothing until the voltage drops below a certain preset threshhold, at which time they will take over supplying power to the load. These often use a very rudimentary inverter section, which generates a pretty lousy approximation of a sine wave. Watch out for these products - they can create problems for sensitive equipment with linear power supplies. They're fine for PCs and other devices that use switching supplies, however, as these devices generally aren't sensitive to voltage harmonics.
The better UPSs are 'Online Double-Conversion'. This type of UPS is always in the circuit, with the DC bus being fed by a combination of the inverter and the batteries. This design provides a glitch-free transition from line power to battery power, and inherently provides voltage regulation and frequency regulation. That said, it is still possible to find cheap UPSs with inverters that do not provide a filtered output. For sensitive equipment that needs continuous power, you want to have an Online UPS with output filtering; this provides a clean 60Hz voltage waveshape. These will almost always have enough internal TVSS protection to suffice, so this really will cover all the bases, assuming you also have a whole-house TVSS installed at your service entrance or main panel.
Hope this helps.......