CareBase is a manufacturer's representative for three power quality products manufacturers, and also acts as a power quality/power protection consultant. From over 15 years of experience helping people diagnose and solve power problems, plan mission-critical solution strategies for ensuring uptime, etc... we would like to offer a basic strategy for power protection.

The strategy employs different technologies. We represent the three manufacturers we do because a comprehensive strategy for any mission-critical application will almost always employ topologies from all three. Also, unusually enough, these three engineering groups work very well in coordination with each other in some major projects even though they sometimes have competitive overlap. They've earned my greatest respect over the years.

(* Please note, these are my personal opinions, and may or may not represent the views of the respective manufacturers whose products are recommended here).

The power quality two step

1. ABSOLUTELY have a good first line of defense against surges coming in on ac power lines... hopefully with a Meter-Treater® meter-based surge arrester/suppressor, (or if that's not possible, a hardwire Meter-Treater® service entrance class surge protection device), designed to handle lightning. Even if you don't have much lightning where you are, if you have one of these that is DESIGNED with even direct lightning strikes in mind, then you have a device potent enough to handle the majority of other caused surges (in the event of a direct lightning strike a lot can happen due to the radiated electro-magnetic impulse that doesn't care too much about wires and can go right through walls, but, a good surge arrester will still do it's best, you'll probably see some of it vaporized, but in the process will hopefully save your equipment from being toasted due to it's diverting the worst of it to the ground rod).
   
   A good surge arrester, such as the Meter-Treater®, are simply too powerful, and too inexpensive, not to have. We prefer the Meter-Treater® device as it provides not only a tight clamping voltage, combined with high surge handling characteristics and asymmetrical fault current ratings, but also because it is lightning laboratory tested with high energy impulses four times the energy of typical lightning strokes, and is UL, cUL or ETL Listed.
   
2. The next step, customized or tailored to the specific application, is to have "second stage" protection. The reason is because even though many service entrance MOV based surge arresters can admirably handle incredibly high amperage surges and transients... the reality is... as the amperage of the surge goes up, so does the MOV clamping voltage. Not many people realize this, and most manufacturers don't go out of their way to let people know (and to toot their horn for them, M-Ti is one noteworthy exception). 
   Bottom line, in a good defense, you need to have a second stage protector to handle the remaining let-through voltage and amperage of those kinds of impulses. Between the two stages, you have a survivable scenario to even 80,000 amperes transients (which is approximately four times the amperage of an average Colorado lightning stroke).  
   
   Please take a look at the results table on 'let-through' voltages with even adding just an inexpensive plug-in type surge protector:
   Let-through voltage table for Meter-Treater and a second stage protector

So, next, one must make a value judgment on your electronics and appliances.

Please take notes as you review this and other relevant sites, and list what protector, conditioner, voltage regulator, UPS, etc you think you would prefer. It is best if you then take or fax the sheet to your local electric utility/power quality specialist/engineer, or call us. Go over it with them, and ask what they would recommend if they were in your situation.

There are essentially four classes of "second stage" protectors

Ac surge protectors/arresters / power line filters
Ac low-impedance isolation transformer power line conditioners
   and PWM electronic / automatic ac voltage regulators
Ac uninterruptible power supplies (UPS), some with low-impedance
   isolation transformer conditioning or voltage regulation built-in
Dc surge protector / filters for telephone, coaxial cable, satellite
   or data lines

Ac low-impedance isolation transformer power conditioners and PWM-
   IGBT based electronic voltage regulators and automatic voltage regulators

These units from TSi Power act as surge protectors, AND also work on cleaning up the sine wave and eliminating electrical 'noise' on the line. Low-impedance isolation transformer based power conditioners are usually more expensive than typical surge protectors, but the long-term 'return on investment' is quite substantial. Some companies have achieved paybacks of less than one year simply from the reductions in 'no trouble found' service calls. There are some instances where these are not only advisable, but are considered necessary. i.e. in medical laboratories. Isolation and ferroresonant transformer conditioners have what is called a neutral-ground output, which effectively create a zero volt logic ground reference for the highest degree of chip logic accuracy. Result, faster operations and less lock-ups or erroring. And, for audiophiles ... audio systems sound incredibly pure with low-impedance isolation transformers or the new PWM IGBT based electronic voltage regulators.

Voltage regulators now come in three varieties: one uses basic tap-switching transformer technology and is useful for most applications needing voltage regulation, another is ferroresonant constant voltage transformer regulation (quite impervious to electrical noise), and the newer electronic pulse width modulation (uses IGBTs) ac voltage regulation technology which borrows from state-of-the-art UPS technology. This new PWM ac automatic voltage regulator is absolutely the most precise technology possible. Ac voltage regulation is almost mandatory for systems going to developing countries with unstable ac mains.

Ac uninterruptible power supplies/systems (UPS), some with isolation
   transformer conditioning/voltage regulation built-in

Good uninterruptible power supplies are the most expensive for second stage protection. Unfortunately, many people buy "cheap" UPS thinking they are getting the protection inherent in larger "state-of-the-art" UPS. This is not the case. In the past, we have too often had to unplug someone from their "discount" UPS to fix their problems. It is fairly axiomatic that the cheaper the UPS, the worse the electrical output when you look at it on an oscilloscope - and you need to look at it when it is on backup, because that is when you are doing the frantic file saves while also hoping your batteries are still in good shape. Unfortunately, few people have the capability to look at their UPS power on an oscilloscope. 

The least expensive grade uninterruptible power supply we recommend is of the "standby" or single conversion variety, and our favorites here are the basic Flexible and XUPs Series UPS manufactured by TSi Power Corporation. With two XUPs Series units and one automatic transfer switch making for a redundant power source system, you can have a true mission-critical backup solution.

The UPS we recommend for mission-critical systems are any of the Falcon true on-line double conversion sine wave UPS, and then to make them redundant by use of a TSi Power automatic transfer switch. This is simply the most reliable configuration on the market for small servers and telecom systems. To make your power availability reach even higher, I would also recommend an ethanol, or other fuel, motor generator back up one, or worst case - both, of the UPS.

Ac surge protectors/suppressors/arresters/power line filters

For those on a tight budget, M-Ti Multi-Treater's and Pro-Treater's do an excellent job of protection when used in conjunction with electric meter based Meter-Treater®'s. At minimum, place one of these at the point-of-use of any valuable electronic device, such as a TV, VCR, telephone/modem, answering machine, fax machine, copier etc.

Dc surge protector - line filters for telecommunications, cable or data lines

Along with any of the above, for mission-critical applications, pay attention to your data or telephone lines connections that go into your systems to truly have a complete strategy of protection. A computer may be protected through a surge arrester, but if the modem line going into to is not, there is still a backdoor entry way for induced noise or a transient to get in and destroy the machine. This is especially important for broadband, satellite and cable systems. They ALL must have a "bubble of protection" around each device.  

M-Ti has a complete line of data, telecom and dc surge protectors with over 3,000 different combinations available. Any dc line into a computer, telecom or other system is a potential pathway in for destructive impulses such as induced surges from nearby lightning strikes.

I realize this is something most people are unwilling to do because it requires more effort than it seems worth at first... you have to stick your head behind machines you don't want to, get your hair all dusty, then have to come back out for a flashlight and sometimes a mirror to see what you're really looking at, and then often don't even know what to call the connector even as you hold it in your hand. *grinning* I empathize with you. I've been there too many times. But, protecting your incoming data lines really is a necessary component of any power protection strategy. Without it, your machine really isn't truly all the way under a protection umbrella.

1. Dc to ac inverters are a product category to themselves. These inverters come into play for telecom applications or dc solar panel/wind/hydropower applications where it is necessary to provide ac power from an existing battery bank or dc power source.
2. Automatic transfer switches for enabling redundant use of sine wave UPS, inverters, or other sine wave ac power sources, to achieve the highest levels of uptime. If one UPS or power source fails for whatever reason, the ATS simply switches over to the redundant power source fast enough that the load stays up.
3. Split or three phase power monitors that will automatically shut down motors in the event of single phasing. This will prevent burning up motors from single phasing associated over-heating. (These are sometimes required by local electrical codes).
4. Make sure your electrical wiring is up to code, and that is has a well-connected ground rod, and tight "single point grounding" (NEC - NFPA 70). Beware of multiple ground rods not bonded to each other. Your electrical contractor or electrical inspector can help you verify the quality of your grounding system. Surge arresters divert surges to the ground. If a good 'earth ground' is present, and your wiring is tight and up to code, your surge protection strategy will do its job well. And of course, don't forget static mats or some other static electricity strategy for sensitive electronics where static electricity may be an issue. 
5. Finally, clean the system and computers fan(s) on a regular basis. Not even a UPS can help you if your system shuts off from overheating itself.

There you possibly have the shortest yet still fairly comprehensive "Power Quality Solution Strategy" ever written. Please note that it is only for general situations. You may have something unusual that needs to be addressed by a power quality consultant (typically an electrical engineer) or your electric utility company's power quality specialist (hopefully they have at least one). Also, please feel free to contact me if you have any questions you think I might be able to help you with.

Take care,
Michael Gibson

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