Clean power is important to the safety of your equipment.
There are three key issues to consider when buying a surge protector or UPS. Look for:
- Clamping voltage. This tells you what voltage will cause the MOVs to conduct electricity to the ground line. A lower clamping voltage indicates better protection. There are three levels of protection in the UL rating -- 330 V, 400 V and 500 V. Generally, a clamping voltage more than 400V is too high.
- Energy absorption/dissipation. This rating, given in joules, tells you how much energy the surge protector can absorb before it fails. A higher number indicates greater protection. Look for a protector that is at least rated at 500 joules. For better protection, look for a rating of 1500 joules or more.
- Response time. Surge protectors don't kick in immediately; there is a very slight delay as they respond to the power surge. A longer response time tells you that your computer (or other equipment) will be exposed to the surge for a greater amount of time. Look for a surge protector that responds in less than one nanosecond.
The difference between cheap ones and good ones is the response time. Look at the detailed spec for the board.
Eg:
http://www.scorptec.com.au/computer/...f9g823au2m-gry- 2700 Joules - The joule rating is a measurement of the energy a surge protector can absorb. A higher joule rating reflects higher-quality surge protection and longer product life
- 75,000 Amp maximum spike current - Maximum spike current is measured by amperage. A higher rating reflects greater absorption capacity against lightning or sudden dramatic power surges
- 6000 Volt maximum spike voltage
- Clamping voltage 395V
- <1 Nanosecond response time - A rating of <1 nanosecond (a billionth of a second) is an instantaneous response that prevents harmful power disturbances from damaging your equipment
NOTE: These protectors work by diverting the overload to earth. So for safety reasons please ensure your earth circuits are in good order. Always used a licensed electrician for permanent installations.